Water Quality at Bakun HEP Reservoir Belaga Sarawak
WiUieKoh
(44620)
Bachelor of Science with Honours (Aquatic Resource Science and Management)
2016
Pusat 1 UNM
1111111111111111111111111 1000272665
Water Quality at Bakun HEP Reservoir Belaga Sarawak
Willie Koh (44620)
This dissertation is submitted in partial fulfilment of the requirements for the degree of
Bachelor of Science with Honours in Aquatic Resource Science and Management
Faculty of Resource Science and Technology
Universiti Malaysia Sarawak
2016
DECLARATION OF AUTHORSHIP
I Willie Koh declare that the final year project report entitled
Water Quality at Bakun HEP Reservoir Belaga Sarawak
and the work presented in the report are both my own and have been generated by me as
the result of my own original research I confirm that
bull this work was done wholly or mainly while in candidature for a research degree at
bull this University
bull where I have made corrections based on suggestion by supervisor and examiners
bull this has been clearly stated
bull where I have consulted the published work of others this IS always clearly
attributed
bull where I have quoted from the work of others the source is always given With the
bull exception of such quotations this report is entirely my own work
bull I have acknowledged all main sources of help
bull where the thesis is based on work done by myself jointly with others I have made
bull clear exactly what was done by others and what I have contributed myself
bull none of this work has been published before submission
Signed
Aquatic Resource Science and Management Department of Aquatic Science Faculty of Resource Science and Technology Universiti Malaysia Sarawak (UNIMAS)
I
ACKNOWLEDGMENT
My utmost gratitude and thanks to my supervisor Professor Dr Lee Nyanti Janti
ak Chukong for his valuable advice suggestions guidance constructive criticisms and
commitment from the start of this research until the final submission of this thesis
Besides that a special thanks to my co-supervisor Associate Professor Dr Ling Teck Vee
on the guidance and support
I would also like to express my appreciation to the staff of the Department of
Aquatic Science Mr Benedict ak Samling and Mr Richard Toh for their friendly help
and facilitation during the field work and laboratory work Not forgetting my fellow peers
who helped me and for their valuable support Also special thanks to my seniors Angie
Sapis and Ahmad Aklunal Atan for the precious advice Without their kind support and
technical assistance it would not be an easy task to complete this study Also warmest
regards and thanks to Mr Laing and his family for providing us a comfortable
accommodation during our field work in Bakun
Special thanks also goes to Sarawak Energy Berhand for the financial assistance in
this study through the research grant no GL (F07)SEB4A12013 (24)
Finally my family members are highly acknowledged for their understanding and
never ending support To those who indirectly contribute to this research your kindness is
greatly appreciated All praises to God for the strength and opportunity for completing this
thesis Without his mercy I may not be able to go through the tough times in the course of
this study
II
i
Water Quality at Bakun HEP Reservoir Belaga Sarawak
Abstract
Since the water supply at Bakun Hydroelectric Dam reached its full supply level only one previous study has been done during the filling phase of the dam which was 3 years and 10 months earlier than this study As water in the reservoir is very important for the aquatic organisms in the reservoir and downstream of the dam a study was conducted at 3 stations to determine the selected water quality parameters 5 years 6 months after impoundment started At each station water in triplicate samples were collected at 6 levels which is the subsurface at 10m 20m 30m 40m and 50m depth Results showed that thermocline occurred at 3m to 10m depth at all stations DO at the subsurface (499 - 610 mgL) dropped drastically to anoxic level starting from 2m to 10m depth at all stations Water conductivity and turbidity increases while pH decreased as depth increased The highest chlorophyll-a (1168 J-lgL) was recorded at 10m depth with positive correlation with turbidity Increasing levels of ammonia-nitrogen (00533 - 06400 mgL) total suspended solids (330 - 6306 mgL) and five-day biochemical oxygen demand (186 - 430 mgL) were observed while depth increases Nitrate (001 - 022 mgL) nitrite (00020 - 01170 mgL) silica (039 - 154 mgL) and orthophosphate (00900 - 17067 mgL) showed different variations with depth This present study showed that the water quality at Bakun Hydroelectric Dam was improving and still changing compared to the previous study during the filling phase and has not stabilize even after 5 years 6 months after impoundment started
Keywords hydroelectric dam turbidity water quality nutrients
Abstrak
Sejak bekalan air di Empangan Hidroelektrik Bakun mencapai tahap penuh hanya satu kajian telah dijalankan semasa fasa pengisian iaitu 3 tahun dan 10 bulan lebih awal daripada kajian ini Disebabkan air di dalam empangan adalah sangat penting untuk organisma akuatik di dalam empangan dan bawah empangan satu kajian telah dijalankan di 3 stesen untuk mengenalpasti parameter kualiti air 5 tahun selepas penakungan bermula Di setiap stesen air telah diambil sebanyak tiga kali daripada 6 tahap iaitu subpermukaan 10m 20m 30m 40m dan 50m Hasil kajian menunjuk perbentukan termoklin pada kedalaman dari 3m ke 10m di semua stesen DO di subpermukaan (499shy610 mglL) menurun dengan drastik kepada tahap anoksik bermula pada kedalaman 2m ke 10m di semua stesen Konduktiviti air dan kekeruhan meningkat dan pH menurun dengan kedalaman Klorofil-a paling tinggi (1168 pgIL) adalah pada kedalaman 10m dan berkorelasi positijdengan kekeruhan air Peningkatan tahap ammonia-nitrogen (00533 shy06400 mgIL) jumlah pepejal terampai (330 - 6306 mgIL) dan keperluan oksigen biokimia selepas lima hari (186 - 430 mglL) meningkat apabila kedalaman meningkat Nitrat (001 - 022 mgIL) nitrit (00020 - 01170 mgIL) silika (039 - 154 mglL) dan ortofosfat (00900 - 17067 mglL) menunjukkan variasi yang berbeza dengan kedalaman Kajian ini menunjukkan bahawa kualiti air di Empangan Hidroelektrik Bakun bertambah baik dan masih berubah berbanding dengan kajian semasa fasa pengisian dan belum lagi staNI selepas 5 tahun dan 6 bulan sejak penakungan bermula
Kata kunci empangan hidroelektrik kekeruhan air kualiti air nutrien
III
Pusat Khidmat Maklumal Akadtmi UNIVEftSm MALAYSIA SAKAWA
TABLE OF CONTENTS
Declaration of Authorship
Acknowledgement
Abstract
Abstrak
Table of Contents
List of Figures
List of Tables
List of Abbreviations
10 Introduction
20 Literature Review
21 Reservoir
22 Water Quality
221 Temperature
222 Dissolved Oxygen (DO)
223 pH
224 Nutrients
23 Impact of Hydroelectric Dams on Water Quality
30 Materials and Methods
31 Study Site
32 Water Samples
33 Water Quality Parameters Measured In-situ
34 Water Quality Parameters Analysed Ex-situ
341 Biological Oxygen Demand (BODs)
342 Total Suspended Solids (TSS)
343 Chlorophyll-a
344 Ammonia-Nitrogen (NH3-N)
345 Nitrate (N03-)
346 Nitrite (N02-)
347 Orthophosphate (P043-)
348 Silica (Si04)
35 Statistical Analyses
Page
I
II
III
III
IV
VI
VII
VIII
3
3
3
4
5
5
6
7
9
9
11
11
11
11
12
13
14
14
15
16
16
17
IV
18 40 Results
41 Water Quality Parameters Measured In-situ 18
411 Water Depth and Transparency 18
412 Temperature 18
413 Ph 23
414 Water Turbidity 26
415 Water Conductivity 28
416 Dissolved Oxygen (DO) 31
42 Water Quality Parameters Measured Ex-situ 35
421 Chlorophyll-a 35
422 Biochemical Oxygen Demand in Five Days (BOD5) 37
423 Nitrate (NOf) 39
424 Nitrite (N02-) 42
425 Ammonia-Nitrogen (NH3-N) 44
426 Silica (Si04) 46
427 Orthophosphate (P043-) 48
428 Total Suspended Solids (TSS) 50
50 Discussion 52
51 Water Parameters Measured In-situ 52
52 Water Parameters Measured Ex-situ 57
60 Summary 63
70 Conclusion 65
80 References 66
90 Appendices 71
v
I
Figure
Figure 1
Figure 2
Figure 3
Figure 4
Figure 5
Figure 6
Figure 7
Figure 8
Figure 9
Figure 10
Figure 11
Figure 12
Figure 13
Figure 14
Figure 15
Figure 16
Figure 17
Figure 18
Figure 19
Figure 20
Figure 21
Figure 22
Figure 23
Figure 24
Figure 25
Figure 26
Figure 27
Figure 28
Figure 29
Figure 30
Figure 31
-
LIST OF FIGURES
Title Page
The location of sampling stations at Bakun Dam Sarawak 10
19
Temperature values in November 2015
Temperature values in August 2015
21
Temperature profile in August 2015 22
Temperature profile in November 2015 23
PH values in August 2015 24
PH values in November 2015 25
Turbidity values in August 2015 27
Turbidity values in November 2015 28
Water conductivity values in August 2015 29
Water conductivity values in November 2015 30
Dissolved oxygen (DO) values in August 2015 32
Dissolved oxygen (DO) values in November 2015 33
Dissolved oxygen (DO) profile in August 2015 34
Dissolved oxygen (DO) profile in November 2015 34
Chlorophyll-a values in August 2015 36
Chlorophyll-a values in November 2015 37
BODs values in August 2015 38
BODs values in November 2015 39
Nitrate-N values in August 2015 41
Nitrate-N values in November 2015 41
Nitrite-N values in August 2015 43
Nitrite-N values in November 2015 43
Ammonia-N values in August 2015 45
Ammonia-N values in November 2015 45
Silica values in August 2015 47
Silica values in November 2015 47
Orthophosphate values in August 2015 49
Orthophosphate values in November 2015 49
TSS values in August 2015 51
TSS values in November 2015 51
VI
LIST OF TABLES
Table Title Page
Table 1 Coordinates and locations of sampling stations 10
Table 2 Water depth and transparency values in August 2015 18
Table 3 Classification of water quality parameters according to NWQS 64
VII
LIST OF ABBREVIATIONS
degC Degree Celsius
lm Micrometre
BOD Biological Oxygen Demand
DO Dissolved Oxygen
km2 Kilometre Square
3m Cubic Metre
mgL Milligram per litre
mL Millilitre
L Litre
nm Nanometre
mm Millimetre
pH Potential of Hydrogen
N Nitrogen
N02- Nitrite
N03- Nitrate
P04 3- Orthophosphate
Si04 Silica
NH3-N Ammonia-Nitrogen
TSS Total Suspended Solids
TDS Total Dissolved Solids
GPS Global Positioning System
VIII
10 Introduction
Hydroelectric dams have been constructed worldwide to provide an alternative
energy source as petroleum in the world is depleting and is not renewable Hence
impoundment started around the world to collect water bodies to act as a reservoir
Reservoirs formed by impoundment they will undergo great changes in water
quality (Chapman 1996) This was observed in tropical reservoirs such as Feitsui
Reservoir in Taiwan (Chang and Wen 1997) and Lake Brokopondo in Surinam (Van der
Heide 1978) and also temperate reservoirs such as Butgenbuch Reservoir in Belgium
(Lourantou et aI 2007) and Bureye Reservoir in Russia (Shesterkin 2008) This happens
because of the impact of inundated soil and vegetation including the standing forest on the
water quality such as pH level and dissolved oxygen concentration (Van der Heide 1978
Shesterkin 2008) which is essential for aquatic life
In Malaysia hydroelectric dams have been constructed to meet the energy needs
and security Among the hydroelectric dams that have been built in Sarawak is the Bakun
Hydroelectric Dam Construction of the dam started in 2002 It is located about sixty
kilometers from the town of Belaga and is situated on the Balui River Bakun
Hydroelectric Dam is the largest hydropower project in Malaysia that can produce up to
2400 MW of electricity (httpwwwsarawakenergycomrny)Itis the second highest
concrete faced rockfill dam in the world with an area of 695 square kilometers and a height
of 207 meters (httpwwwsarawakenergycomrny) Research on the characteristics of
physico-chemical water quality at Bakun Dam has been conducted by Nyanti (2012)
However it was conducted during the filling phase of the hydroelectric dam which is
fifteen months after impoundment has started Since then there has been no publishing
literature on the characteristics of the water quality
1
Hence the goal of this study is to obtain detailed information on the physicoshy
chemical water properties of the Bakun Hydroelectric Dam 3 years and 7 months after it
has reached its full supply level Therefore the objectives of this study were
(i) To determine the water quality at six depths at three stations in the
reservOIr
(ii) Compare the characteristics of the water quality among the depths and
stations and
(iii) Determine the changes in water quality characteristics 5 years 6 months
after the dam was impounded
2
jl - - I
20 Literature Review
21 Reservoir
According to Pawar amp Shembekar (2012) water is important and it is the most
abundant resource in the world which man has used for decades Water covers about 70
of the earths surface but only 27 of the total amount is freshwater of which 1 is iceshy
free water in the rivers lakes and atmosphere as biological water It is believed that only
0001 92 of the total water on earth is available for human use (Pawar amp Shembekar
2012) Hence reservoirs are created in order to provide domestic water supply generation
of electricity and aquaculture In Malaysia 63 large reservoirs with a total storage of 25
billion m3 have been constructed (Makhlough 2008)
Water quality in reservoirs is greatly affected by the composition of plant materials
that were submerged during the inundation process In a study done by Ling (2012) water
in the Batang Ai reservoir contains high sulfide concentrations especially at inundated
areas Besides that Nyanti (2012) also reported that the anoxic condition and the acidic
condition in Bakun Dam is due to the decomposition of submerged carbonaceous
materials
Additionally human activities in and around reservoirs and the physical and
chemical properties of water will be affected (Mustapha 2008) Precipitation evaporation
and ground movement can also affect water quality In Batang Ai reservoir the dissolved
oxygen was reported to be lower due to nearby cage aquaculture as it is consumed by
microorganisms in the decomposition of organic matter (Ling 2012)
22 Water quality
Water quality in a reservoir is the physical and chemical limnology of a reservoir
(Sidnei 1992) and includes all physical chemical and biological aspects of water that
3
influence the beneficial usage of water (Mustapha 2008) In reservoirs water quality
deterioration usually comes from excessive nutrient inputs eutrophication acidification
heavy metal contamination organic pollution and obnoxious fishing practices (Mustapha
2008)
Therefore water quality is an important indicator of the ecological status of a
reservoir It is reported that the significant lower dissolved oxygen is recorded due to
higher turbidity and increased suspended solids which affect the dissolution of oxygen
which is brought in by the flood that occurred in Oyun Reservoir (Mustapha 2008)
Additionally in a study done at Bakun Dam turbidity is affected by the suspended solids
from eroded soils from the logging activities in the watershed upstream from the north of
the reservoir (Nyanti 2012)
221 Temperature
Temperature is very important to a reservoir as it affects chemical and biological
activities of aquatic organisms (Sangpal 2011) In a reservoir when the upper layer and
the lower layer have great variation in temperature thermocline will occur Thermal
stratification in deep reservoir is an important natural process which gives significant
effects on water quality The production of ammonia sulphide and algal nutrients are
dependent on the changes in water temperature which subsequently affects the water
quality (Baharim 2011) Besides that vertical distribution and change in water
temperature can affect productivity of the natural organisms in the reservoirs However
the effect varies from reservoir to reservoir According to Li amp Xu (1995) thermocline is
common in reservoirs and usually occurs at the depth of 8m to 23m In a study done by
Nyanti (2012) water temperature in Bakun reservoir was reported to undergo thermocline
as depth increased from subsurface to 18m
4
l I
Pusat Khidmat Maldumat Akadfmil UN nsmMALAYSIA SARAWAI~
222 Dissolved Oxygen (DO)
DO is a very essential environmental factor that affects the entire production of a
reservoir and it is also an important indicator of water quality health of reservoir and also
ecological status as it is used for respiration and in biological and chemical reactions
(Mustapha 2008)
DO fluctuate from reservOIr to reservOIr and it is usually affected by
photosynthesis respiration and diel fluctuation In a study done by Ling (2012) it was
reported that the DO is higher at 05m depth at a11 stations in Batang Ai reservoir ranging
from 47 to 87 mgL due to the high phytoplankton photosynthesis rate An example of
diel fluctuation is shown in Kontagora reservoir where the DO is higher during the dry
season than the rainy season (Ibrahim 2009) This shows that the fluctuation also depends
on temperature depth wind and amount of biological activities such as decomposition In
Bakon Dam DO is high at the subsurface but dropped drastically until anoxic level at
depth 2 - 4m 2 years after impoundment and this is mainly due to the decomposition of
organic matter (Nyanti 2012)
223 pH
pH that is suitable for optimal production for inland waters should be about 65 to
85 (Ibrahim 2009) However changes in pH can affect the transfer of nutrients and affect
the condition ofwater quality (Li amp Xu 1995)
Fluctuations in pH can be caused by the photosynthesis process of phytoplanktons
as was reported in Batang Ai reservoir where all pH value was above 7 (Ling 2012)
Carbon dioxide produced by photosynthesis process will alter the pH of water as carbonic
acid will be formed when carbon dioxide reacts with water (Sangpal 2011)
5
Acidic effects in reservoirs can be caused by the transfer of cooler water from other
tributaries where the water is denser and lower in pH Nyanti (2012) reported the pH value
at Bakundam were all acidic ranging from 517-592 and the overall trend of pH in Bakun
dam decreases from upstream towards the dam (Nyanti et aI 2012)
224 Nutrients
Reservoirs are often have higher chances of getting higher element loading
compared to natural lakes as they have greater catchment area and high inflow rates
(Pawar amp Shembekar 2012) The concentration of nutrients varies from reservoir to
reservoir due to the differences in soil and vegetation in the catchment area (Li amp Xu
1995) Nutrients such as nitrates phosphates silicates and iron are important nutrients
required for aquatic growth but may also cause eutrophication and water quality problems
(Li amp Xu 1995) Eutrophication can occur easily in reservoir due to high input of nutrients
into the water and water quality of reservoir will be affected giving rise to unpleasant taste
and odour and affects the dissolution of other gases especially dissolved oxygen
(Mustapha 2008) According to Nyanti (2012) strong rotten egg smell discovered in
Bakun dam indicates high volume of hydrogen sulfide This observation is also supported
by Lourantou (2007) where an irritating odour smell occurs at a reservoir in Belgium
Nutrients input can also be affected by weather and season where nitrate was recorded at
higher values in Ujjani reservoir during post-monsoon season This may be caused by the
oxidation of nitrifying bacteria and biological nitrification Sulphate concentrations in the
dam were very high in both pre and post-monsoon which were probably caused by the
mineral rocks anthropogenically added and also by rain (Sangpal 2011) The phosphate
levels were found to be lower during the pre-monsoon and higher during the postshy
6
monsoon Phosphate leads to eutrophication that can cause unpleasant taste and odour to
the water (Sangpal 2011)
23 Impacts of hydroelectric dams on water quality
Hydroelectric dam has a direct impact to the water quality as it uses the flow rate of
a water course to produce electricity The building of hydroelectric dams has direct impact
towards the chemical thermal and physical parameters of the water body (Bunea 2012)
According to a study done by Bunea (2012) hydroelectric dams have relatively low DO
concentration mostly lower than 50 mglL because of the organic sediments that are left at
the bottom of the reservoir bottom during the initial filing Organic substances left at the
bottom of the reservoir bottom floor will absorb oxygen from the water in order to
decompose producing hydrogen sulphide carbon dioxide and methane (Bunea 2012)
Due to damming for hydroelectric generation water in a reservoir will undergo
stagnation which will lead to thermal stratification (Bunea 2012) According to a study
done by Elci (2008) thermal stratification of the reservoir involves the higher temperature
at the surface and lower temperatures at the bottom which suggests that thermal energy is
very slowly transferred to the bottom layers of the water body Thermal stratification act as
a barrier to re train mixing of the water column This causes an uneven concentration of
nutrients lack of light for photosynthesis at the hypolimnion and the water column may
become anoxic (Elci 2008)
Hydroelectric dams also greatly reduces the water self-purification capacity
According to Wei et al (2009) water self-purification mechanisms are affected by the
physical chemical and biotic processes in a reservoir However dam construction affects
all of the processes as the flow regime water quality and biotic community in the river In
other words dams slow down the river flow capacity block the river continuum and raise
7
water temperature which decreases the water self-purification capacity (Wei et aI 2009)
In a study done in China by Wei et al (2009) it is recorded that the Manwan-Dachaosan
dam has higher ammonia-nitrogen concentration due to the decreased water selfshy
purification capacity as compared to the pre-dam period This suggests that damming has
severely decreased the water self-purification capacity as it blocked the river continuum
8
30 Materials and Methods
31 Study Site
Bakun Hydroelectric Reservoir is a man-made reservoir which is located 60 km
west of Belaga Sarawak Malaysia (Figure 1) The dam was formed after the
impoundment of Balui River The reservoir has a catchment area of 14750 km2 and a total
capacity 43800000 m3 with a surface area of 695 km2 The dam is the second tallest
concrete-faced rockfill dam in the world
Three sampling stations namely stations 1 2 and 3 was selected in the reservoir
Station 1 is at the inundated estuary of the Linau River Station 2 is at the inundated Balui
River and Station 3 is located in the inundated Balui River as well but nearer to the dam
At each station sampling was conducted at 6 levels namely the subsurface 10m 20m
30m 4Om and 50m depths The coordinates of Bakun dam is at longitude 02deg45 23N and
latitude 114deg0347E The coordinates of every sampling station were recorded by the
Global Positioning System (GARMIN GPSMAP 62S) (Table 1) Sampling was carried
out twice the first sampling was from 21 SI August to 27th August 2015 and the second
sampling was 5th November to 11 th November 2015
9
i
EAST MALAYSIA
o
I
-I River I
-I Flooded Area
Station
0 Dam
kill I
Figure 1 Location of the three sampling stations at Bakun Reservoir
Table 1 Coordinates and locations of sampling stations
Station Coordinates Location
N 02deg 39 322 E 114deg 03 295 Estuary of Linau River
2 N 02deg 43 344 E 114deg 01 442 Balui River
3 N 02deg 43 4135 E 114deg 03 340 Further downstream of Balui River
10
32 Water samples
The water samples were taken using Van Dorn water sampler at all three stations
and were taken at 6 different depths which are the subsurface (02m) 10m 20m 30m 40m
and 5Om At each station three replicates of water samples were taken back for laboratory
analysis Water samples were kept in 2 L polyethylene water bottles that has been acid
washed and were stored in cooler box filled with ice All samples were taken to the
laboratory for further analysis
33 Water quality parameters measured in-situ
Temperature dissolved oxygen (DO) pH electrical conductivity total dissolved
solids (TDS) and turbidity were taken using YSI Multiparameter Water Quality 6920 V2
The depths of each station were measured using depth finder Water transparency was also
measured using secchi disc at each station
34 Water quality parameters analysed ex-situ
341 Biochemical oxygen demand in five days (BODs)
BODs were determined by filling water samples into 300 ml BOD bottles DO
readings of the water samples were measured from the bottles All BOD bottles were
wrapped with aluminum foil to prevent light penetration and were kept in a cooler box for
5 days The initial DO value was recorded as DJ and on the 5th day the DO reading was
recorded as Ds The formula that was used for measuring BODs follows the protocol
outlined by APHA (1998)
11
BOD5 (mglL) = DJ - D5
Where DJ = Initial DO of sample immediately after preparation (mglL)
D5 = DO value after 5 days incubation at 25degC (mglL)
342 Total suspended solids (TSS)
Total suspended solids were analyzed using standard method APHA (1998) For
TSS analysis there was pre-fieldtrip sampling method and post-fieldtrip method For preshy
fieldtrip method glass fibre filter paper (GFIC 47 nun diameter 045 Ilm membrane) were
soaked in distilled water Each filter paper is placed on a piece of aluminum foil and was
dried in the oven at 103degC - 105degC overnight Filter paper then was allowed to cool for 10
minutes before weighing it using an analytical balance (ACCULAB ALC - 210) The
initial weight was recorded For post-fieldtrip method the glass fibre paper was placed on
the inter-plate of the filter funnel using a pair of forceps A known volume of water
samples was filtered using a vacuum pump After that filter paper was removed from the
filtration funnel and was placed back into the aluminum foil Filter paper was dried in the
oven at 103degC - 105degC overnight (APHA 1998) Filter paper was then taken out of the
oven and allowed to cool until room temperature before weighing The final reading of the
filtered glass fibre paper was recorded and TSS was calculated using the formula
w -wTSS (mglL) = J I
V
Where W = Initial weight of filter paper
WJ = Final weight of filter paper
V = Volume of water samples filtered (L)
12
4 Chlorophyll-a
The concentration of chlorophyll-a In the water samples were analyzed using
staDdard method APHA (1998) For chlorophyll-a analysis water samples were filtered
using vacuum pump Filter paper containing chlorophyll-a was taken from the vacuum
pump for analysis The samples were grinded by using a grinder and 5 - 6 mL of 90
acetone was added into the mortar Samples were grinded for about 5 minutes and all
materials in the mortar were placed into a capped test tube Ninety percent acetone was
added into the test tube to make up the volume to 10mL Test tube was folded with
aluminum foil and was placed in the refrigerator for 4 - 18 hours to facilitate complete
extraction of the pigments The liquid extracted was transferred into the centrifuge tube
The samples were placed into a centrifuge for about 10 minutes under 3000 rpm Optical
density was determined using spectrophotometer at wavelength of 750 nm 664 run 647
am and 630 nm Each extinctions for small turbidity blank was corrected by subtracting
750 nm from 664 nm and 630 run absorptions
The concentration of chlorophyll-a in the extract of the pigment after correction was
calculated using
Where E = the absorption in the respective wavelength
After determining the concentration of the chlorophyll-a in the extract the amount of
cblorophyll-a in the pigment per unit volume of water filtered was calculated as follows
13
Ca(v)Chlorophyll-a (Jg IL) = - shyv
Where Co = Chlorophyll-a pigment concentration in JgmL
v = Volume ofacetone in mL
v = Volume of samples in L
344 Ammonia-nitrogen (NH3-N)
For ammonia-nitrogen (NH3-N) the concentration was determined using standard
method 8038 Nessler Method (HACH 2000) A 25 mL prepared sample and 25 mL of
deionized water were filled into a separate 25 mL mixing graduated cylinder Three drops
of Mineral Stabilizer were added to both of the cylinders The cylinders were inverted
several times to mix the content After that 1 mL of Nessler reagent was pipetted into both
of the cylinders and the cylinders were inverted several times to mix the content A one-
minute reaction was started Both the solutions were poured into a square sample cell A
yellow colour formation will indicate the presence of ammonia When the timer expired
the blank was inserted into the square sample cell with the fill line facing the right The
reading at 425 run was zeroed The prepared sample was inserted into the cell holder of
Spectrophotometer DR 2800 (HACH 2000) with the fill line facing right and the reading
displayed was recorded
345 Nitrate (NO)-)
For nitrate analysis the concentration was determined using standard method 8192
Cadmium Reduction Method (HACH 2000) The sample was filled until the 15 mL mark
of a 25 mL graduated measuring cylinder The content of one Nitra Ver6 Nitrate Reagent
Pillow Powder was added into the cylinder and capped with a stopper The cylinder was
14
Pusat 1 UNM
1111111111111111111111111 1000272665
Water Quality at Bakun HEP Reservoir Belaga Sarawak
Willie Koh (44620)
This dissertation is submitted in partial fulfilment of the requirements for the degree of
Bachelor of Science with Honours in Aquatic Resource Science and Management
Faculty of Resource Science and Technology
Universiti Malaysia Sarawak
2016
DECLARATION OF AUTHORSHIP
I Willie Koh declare that the final year project report entitled
Water Quality at Bakun HEP Reservoir Belaga Sarawak
and the work presented in the report are both my own and have been generated by me as
the result of my own original research I confirm that
bull this work was done wholly or mainly while in candidature for a research degree at
bull this University
bull where I have made corrections based on suggestion by supervisor and examiners
bull this has been clearly stated
bull where I have consulted the published work of others this IS always clearly
attributed
bull where I have quoted from the work of others the source is always given With the
bull exception of such quotations this report is entirely my own work
bull I have acknowledged all main sources of help
bull where the thesis is based on work done by myself jointly with others I have made
bull clear exactly what was done by others and what I have contributed myself
bull none of this work has been published before submission
Signed
Aquatic Resource Science and Management Department of Aquatic Science Faculty of Resource Science and Technology Universiti Malaysia Sarawak (UNIMAS)
I
ACKNOWLEDGMENT
My utmost gratitude and thanks to my supervisor Professor Dr Lee Nyanti Janti
ak Chukong for his valuable advice suggestions guidance constructive criticisms and
commitment from the start of this research until the final submission of this thesis
Besides that a special thanks to my co-supervisor Associate Professor Dr Ling Teck Vee
on the guidance and support
I would also like to express my appreciation to the staff of the Department of
Aquatic Science Mr Benedict ak Samling and Mr Richard Toh for their friendly help
and facilitation during the field work and laboratory work Not forgetting my fellow peers
who helped me and for their valuable support Also special thanks to my seniors Angie
Sapis and Ahmad Aklunal Atan for the precious advice Without their kind support and
technical assistance it would not be an easy task to complete this study Also warmest
regards and thanks to Mr Laing and his family for providing us a comfortable
accommodation during our field work in Bakun
Special thanks also goes to Sarawak Energy Berhand for the financial assistance in
this study through the research grant no GL (F07)SEB4A12013 (24)
Finally my family members are highly acknowledged for their understanding and
never ending support To those who indirectly contribute to this research your kindness is
greatly appreciated All praises to God for the strength and opportunity for completing this
thesis Without his mercy I may not be able to go through the tough times in the course of
this study
II
i
Water Quality at Bakun HEP Reservoir Belaga Sarawak
Abstract
Since the water supply at Bakun Hydroelectric Dam reached its full supply level only one previous study has been done during the filling phase of the dam which was 3 years and 10 months earlier than this study As water in the reservoir is very important for the aquatic organisms in the reservoir and downstream of the dam a study was conducted at 3 stations to determine the selected water quality parameters 5 years 6 months after impoundment started At each station water in triplicate samples were collected at 6 levels which is the subsurface at 10m 20m 30m 40m and 50m depth Results showed that thermocline occurred at 3m to 10m depth at all stations DO at the subsurface (499 - 610 mgL) dropped drastically to anoxic level starting from 2m to 10m depth at all stations Water conductivity and turbidity increases while pH decreased as depth increased The highest chlorophyll-a (1168 J-lgL) was recorded at 10m depth with positive correlation with turbidity Increasing levels of ammonia-nitrogen (00533 - 06400 mgL) total suspended solids (330 - 6306 mgL) and five-day biochemical oxygen demand (186 - 430 mgL) were observed while depth increases Nitrate (001 - 022 mgL) nitrite (00020 - 01170 mgL) silica (039 - 154 mgL) and orthophosphate (00900 - 17067 mgL) showed different variations with depth This present study showed that the water quality at Bakun Hydroelectric Dam was improving and still changing compared to the previous study during the filling phase and has not stabilize even after 5 years 6 months after impoundment started
Keywords hydroelectric dam turbidity water quality nutrients
Abstrak
Sejak bekalan air di Empangan Hidroelektrik Bakun mencapai tahap penuh hanya satu kajian telah dijalankan semasa fasa pengisian iaitu 3 tahun dan 10 bulan lebih awal daripada kajian ini Disebabkan air di dalam empangan adalah sangat penting untuk organisma akuatik di dalam empangan dan bawah empangan satu kajian telah dijalankan di 3 stesen untuk mengenalpasti parameter kualiti air 5 tahun selepas penakungan bermula Di setiap stesen air telah diambil sebanyak tiga kali daripada 6 tahap iaitu subpermukaan 10m 20m 30m 40m dan 50m Hasil kajian menunjuk perbentukan termoklin pada kedalaman dari 3m ke 10m di semua stesen DO di subpermukaan (499shy610 mglL) menurun dengan drastik kepada tahap anoksik bermula pada kedalaman 2m ke 10m di semua stesen Konduktiviti air dan kekeruhan meningkat dan pH menurun dengan kedalaman Klorofil-a paling tinggi (1168 pgIL) adalah pada kedalaman 10m dan berkorelasi positijdengan kekeruhan air Peningkatan tahap ammonia-nitrogen (00533 shy06400 mgIL) jumlah pepejal terampai (330 - 6306 mgIL) dan keperluan oksigen biokimia selepas lima hari (186 - 430 mglL) meningkat apabila kedalaman meningkat Nitrat (001 - 022 mgIL) nitrit (00020 - 01170 mgIL) silika (039 - 154 mglL) dan ortofosfat (00900 - 17067 mglL) menunjukkan variasi yang berbeza dengan kedalaman Kajian ini menunjukkan bahawa kualiti air di Empangan Hidroelektrik Bakun bertambah baik dan masih berubah berbanding dengan kajian semasa fasa pengisian dan belum lagi staNI selepas 5 tahun dan 6 bulan sejak penakungan bermula
Kata kunci empangan hidroelektrik kekeruhan air kualiti air nutrien
III
Pusat Khidmat Maklumal Akadtmi UNIVEftSm MALAYSIA SAKAWA
TABLE OF CONTENTS
Declaration of Authorship
Acknowledgement
Abstract
Abstrak
Table of Contents
List of Figures
List of Tables
List of Abbreviations
10 Introduction
20 Literature Review
21 Reservoir
22 Water Quality
221 Temperature
222 Dissolved Oxygen (DO)
223 pH
224 Nutrients
23 Impact of Hydroelectric Dams on Water Quality
30 Materials and Methods
31 Study Site
32 Water Samples
33 Water Quality Parameters Measured In-situ
34 Water Quality Parameters Analysed Ex-situ
341 Biological Oxygen Demand (BODs)
342 Total Suspended Solids (TSS)
343 Chlorophyll-a
344 Ammonia-Nitrogen (NH3-N)
345 Nitrate (N03-)
346 Nitrite (N02-)
347 Orthophosphate (P043-)
348 Silica (Si04)
35 Statistical Analyses
Page
I
II
III
III
IV
VI
VII
VIII
3
3
3
4
5
5
6
7
9
9
11
11
11
11
12
13
14
14
15
16
16
17
IV
18 40 Results
41 Water Quality Parameters Measured In-situ 18
411 Water Depth and Transparency 18
412 Temperature 18
413 Ph 23
414 Water Turbidity 26
415 Water Conductivity 28
416 Dissolved Oxygen (DO) 31
42 Water Quality Parameters Measured Ex-situ 35
421 Chlorophyll-a 35
422 Biochemical Oxygen Demand in Five Days (BOD5) 37
423 Nitrate (NOf) 39
424 Nitrite (N02-) 42
425 Ammonia-Nitrogen (NH3-N) 44
426 Silica (Si04) 46
427 Orthophosphate (P043-) 48
428 Total Suspended Solids (TSS) 50
50 Discussion 52
51 Water Parameters Measured In-situ 52
52 Water Parameters Measured Ex-situ 57
60 Summary 63
70 Conclusion 65
80 References 66
90 Appendices 71
v
I
Figure
Figure 1
Figure 2
Figure 3
Figure 4
Figure 5
Figure 6
Figure 7
Figure 8
Figure 9
Figure 10
Figure 11
Figure 12
Figure 13
Figure 14
Figure 15
Figure 16
Figure 17
Figure 18
Figure 19
Figure 20
Figure 21
Figure 22
Figure 23
Figure 24
Figure 25
Figure 26
Figure 27
Figure 28
Figure 29
Figure 30
Figure 31
-
LIST OF FIGURES
Title Page
The location of sampling stations at Bakun Dam Sarawak 10
19
Temperature values in November 2015
Temperature values in August 2015
21
Temperature profile in August 2015 22
Temperature profile in November 2015 23
PH values in August 2015 24
PH values in November 2015 25
Turbidity values in August 2015 27
Turbidity values in November 2015 28
Water conductivity values in August 2015 29
Water conductivity values in November 2015 30
Dissolved oxygen (DO) values in August 2015 32
Dissolved oxygen (DO) values in November 2015 33
Dissolved oxygen (DO) profile in August 2015 34
Dissolved oxygen (DO) profile in November 2015 34
Chlorophyll-a values in August 2015 36
Chlorophyll-a values in November 2015 37
BODs values in August 2015 38
BODs values in November 2015 39
Nitrate-N values in August 2015 41
Nitrate-N values in November 2015 41
Nitrite-N values in August 2015 43
Nitrite-N values in November 2015 43
Ammonia-N values in August 2015 45
Ammonia-N values in November 2015 45
Silica values in August 2015 47
Silica values in November 2015 47
Orthophosphate values in August 2015 49
Orthophosphate values in November 2015 49
TSS values in August 2015 51
TSS values in November 2015 51
VI
LIST OF TABLES
Table Title Page
Table 1 Coordinates and locations of sampling stations 10
Table 2 Water depth and transparency values in August 2015 18
Table 3 Classification of water quality parameters according to NWQS 64
VII
LIST OF ABBREVIATIONS
degC Degree Celsius
lm Micrometre
BOD Biological Oxygen Demand
DO Dissolved Oxygen
km2 Kilometre Square
3m Cubic Metre
mgL Milligram per litre
mL Millilitre
L Litre
nm Nanometre
mm Millimetre
pH Potential of Hydrogen
N Nitrogen
N02- Nitrite
N03- Nitrate
P04 3- Orthophosphate
Si04 Silica
NH3-N Ammonia-Nitrogen
TSS Total Suspended Solids
TDS Total Dissolved Solids
GPS Global Positioning System
VIII
10 Introduction
Hydroelectric dams have been constructed worldwide to provide an alternative
energy source as petroleum in the world is depleting and is not renewable Hence
impoundment started around the world to collect water bodies to act as a reservoir
Reservoirs formed by impoundment they will undergo great changes in water
quality (Chapman 1996) This was observed in tropical reservoirs such as Feitsui
Reservoir in Taiwan (Chang and Wen 1997) and Lake Brokopondo in Surinam (Van der
Heide 1978) and also temperate reservoirs such as Butgenbuch Reservoir in Belgium
(Lourantou et aI 2007) and Bureye Reservoir in Russia (Shesterkin 2008) This happens
because of the impact of inundated soil and vegetation including the standing forest on the
water quality such as pH level and dissolved oxygen concentration (Van der Heide 1978
Shesterkin 2008) which is essential for aquatic life
In Malaysia hydroelectric dams have been constructed to meet the energy needs
and security Among the hydroelectric dams that have been built in Sarawak is the Bakun
Hydroelectric Dam Construction of the dam started in 2002 It is located about sixty
kilometers from the town of Belaga and is situated on the Balui River Bakun
Hydroelectric Dam is the largest hydropower project in Malaysia that can produce up to
2400 MW of electricity (httpwwwsarawakenergycomrny)Itis the second highest
concrete faced rockfill dam in the world with an area of 695 square kilometers and a height
of 207 meters (httpwwwsarawakenergycomrny) Research on the characteristics of
physico-chemical water quality at Bakun Dam has been conducted by Nyanti (2012)
However it was conducted during the filling phase of the hydroelectric dam which is
fifteen months after impoundment has started Since then there has been no publishing
literature on the characteristics of the water quality
1
Hence the goal of this study is to obtain detailed information on the physicoshy
chemical water properties of the Bakun Hydroelectric Dam 3 years and 7 months after it
has reached its full supply level Therefore the objectives of this study were
(i) To determine the water quality at six depths at three stations in the
reservOIr
(ii) Compare the characteristics of the water quality among the depths and
stations and
(iii) Determine the changes in water quality characteristics 5 years 6 months
after the dam was impounded
2
jl - - I
20 Literature Review
21 Reservoir
According to Pawar amp Shembekar (2012) water is important and it is the most
abundant resource in the world which man has used for decades Water covers about 70
of the earths surface but only 27 of the total amount is freshwater of which 1 is iceshy
free water in the rivers lakes and atmosphere as biological water It is believed that only
0001 92 of the total water on earth is available for human use (Pawar amp Shembekar
2012) Hence reservoirs are created in order to provide domestic water supply generation
of electricity and aquaculture In Malaysia 63 large reservoirs with a total storage of 25
billion m3 have been constructed (Makhlough 2008)
Water quality in reservoirs is greatly affected by the composition of plant materials
that were submerged during the inundation process In a study done by Ling (2012) water
in the Batang Ai reservoir contains high sulfide concentrations especially at inundated
areas Besides that Nyanti (2012) also reported that the anoxic condition and the acidic
condition in Bakun Dam is due to the decomposition of submerged carbonaceous
materials
Additionally human activities in and around reservoirs and the physical and
chemical properties of water will be affected (Mustapha 2008) Precipitation evaporation
and ground movement can also affect water quality In Batang Ai reservoir the dissolved
oxygen was reported to be lower due to nearby cage aquaculture as it is consumed by
microorganisms in the decomposition of organic matter (Ling 2012)
22 Water quality
Water quality in a reservoir is the physical and chemical limnology of a reservoir
(Sidnei 1992) and includes all physical chemical and biological aspects of water that
3
influence the beneficial usage of water (Mustapha 2008) In reservoirs water quality
deterioration usually comes from excessive nutrient inputs eutrophication acidification
heavy metal contamination organic pollution and obnoxious fishing practices (Mustapha
2008)
Therefore water quality is an important indicator of the ecological status of a
reservoir It is reported that the significant lower dissolved oxygen is recorded due to
higher turbidity and increased suspended solids which affect the dissolution of oxygen
which is brought in by the flood that occurred in Oyun Reservoir (Mustapha 2008)
Additionally in a study done at Bakun Dam turbidity is affected by the suspended solids
from eroded soils from the logging activities in the watershed upstream from the north of
the reservoir (Nyanti 2012)
221 Temperature
Temperature is very important to a reservoir as it affects chemical and biological
activities of aquatic organisms (Sangpal 2011) In a reservoir when the upper layer and
the lower layer have great variation in temperature thermocline will occur Thermal
stratification in deep reservoir is an important natural process which gives significant
effects on water quality The production of ammonia sulphide and algal nutrients are
dependent on the changes in water temperature which subsequently affects the water
quality (Baharim 2011) Besides that vertical distribution and change in water
temperature can affect productivity of the natural organisms in the reservoirs However
the effect varies from reservoir to reservoir According to Li amp Xu (1995) thermocline is
common in reservoirs and usually occurs at the depth of 8m to 23m In a study done by
Nyanti (2012) water temperature in Bakun reservoir was reported to undergo thermocline
as depth increased from subsurface to 18m
4
l I
Pusat Khidmat Maldumat Akadfmil UN nsmMALAYSIA SARAWAI~
222 Dissolved Oxygen (DO)
DO is a very essential environmental factor that affects the entire production of a
reservoir and it is also an important indicator of water quality health of reservoir and also
ecological status as it is used for respiration and in biological and chemical reactions
(Mustapha 2008)
DO fluctuate from reservOIr to reservOIr and it is usually affected by
photosynthesis respiration and diel fluctuation In a study done by Ling (2012) it was
reported that the DO is higher at 05m depth at a11 stations in Batang Ai reservoir ranging
from 47 to 87 mgL due to the high phytoplankton photosynthesis rate An example of
diel fluctuation is shown in Kontagora reservoir where the DO is higher during the dry
season than the rainy season (Ibrahim 2009) This shows that the fluctuation also depends
on temperature depth wind and amount of biological activities such as decomposition In
Bakon Dam DO is high at the subsurface but dropped drastically until anoxic level at
depth 2 - 4m 2 years after impoundment and this is mainly due to the decomposition of
organic matter (Nyanti 2012)
223 pH
pH that is suitable for optimal production for inland waters should be about 65 to
85 (Ibrahim 2009) However changes in pH can affect the transfer of nutrients and affect
the condition ofwater quality (Li amp Xu 1995)
Fluctuations in pH can be caused by the photosynthesis process of phytoplanktons
as was reported in Batang Ai reservoir where all pH value was above 7 (Ling 2012)
Carbon dioxide produced by photosynthesis process will alter the pH of water as carbonic
acid will be formed when carbon dioxide reacts with water (Sangpal 2011)
5
Acidic effects in reservoirs can be caused by the transfer of cooler water from other
tributaries where the water is denser and lower in pH Nyanti (2012) reported the pH value
at Bakundam were all acidic ranging from 517-592 and the overall trend of pH in Bakun
dam decreases from upstream towards the dam (Nyanti et aI 2012)
224 Nutrients
Reservoirs are often have higher chances of getting higher element loading
compared to natural lakes as they have greater catchment area and high inflow rates
(Pawar amp Shembekar 2012) The concentration of nutrients varies from reservoir to
reservoir due to the differences in soil and vegetation in the catchment area (Li amp Xu
1995) Nutrients such as nitrates phosphates silicates and iron are important nutrients
required for aquatic growth but may also cause eutrophication and water quality problems
(Li amp Xu 1995) Eutrophication can occur easily in reservoir due to high input of nutrients
into the water and water quality of reservoir will be affected giving rise to unpleasant taste
and odour and affects the dissolution of other gases especially dissolved oxygen
(Mustapha 2008) According to Nyanti (2012) strong rotten egg smell discovered in
Bakun dam indicates high volume of hydrogen sulfide This observation is also supported
by Lourantou (2007) where an irritating odour smell occurs at a reservoir in Belgium
Nutrients input can also be affected by weather and season where nitrate was recorded at
higher values in Ujjani reservoir during post-monsoon season This may be caused by the
oxidation of nitrifying bacteria and biological nitrification Sulphate concentrations in the
dam were very high in both pre and post-monsoon which were probably caused by the
mineral rocks anthropogenically added and also by rain (Sangpal 2011) The phosphate
levels were found to be lower during the pre-monsoon and higher during the postshy
6
monsoon Phosphate leads to eutrophication that can cause unpleasant taste and odour to
the water (Sangpal 2011)
23 Impacts of hydroelectric dams on water quality
Hydroelectric dam has a direct impact to the water quality as it uses the flow rate of
a water course to produce electricity The building of hydroelectric dams has direct impact
towards the chemical thermal and physical parameters of the water body (Bunea 2012)
According to a study done by Bunea (2012) hydroelectric dams have relatively low DO
concentration mostly lower than 50 mglL because of the organic sediments that are left at
the bottom of the reservoir bottom during the initial filing Organic substances left at the
bottom of the reservoir bottom floor will absorb oxygen from the water in order to
decompose producing hydrogen sulphide carbon dioxide and methane (Bunea 2012)
Due to damming for hydroelectric generation water in a reservoir will undergo
stagnation which will lead to thermal stratification (Bunea 2012) According to a study
done by Elci (2008) thermal stratification of the reservoir involves the higher temperature
at the surface and lower temperatures at the bottom which suggests that thermal energy is
very slowly transferred to the bottom layers of the water body Thermal stratification act as
a barrier to re train mixing of the water column This causes an uneven concentration of
nutrients lack of light for photosynthesis at the hypolimnion and the water column may
become anoxic (Elci 2008)
Hydroelectric dams also greatly reduces the water self-purification capacity
According to Wei et al (2009) water self-purification mechanisms are affected by the
physical chemical and biotic processes in a reservoir However dam construction affects
all of the processes as the flow regime water quality and biotic community in the river In
other words dams slow down the river flow capacity block the river continuum and raise
7
water temperature which decreases the water self-purification capacity (Wei et aI 2009)
In a study done in China by Wei et al (2009) it is recorded that the Manwan-Dachaosan
dam has higher ammonia-nitrogen concentration due to the decreased water selfshy
purification capacity as compared to the pre-dam period This suggests that damming has
severely decreased the water self-purification capacity as it blocked the river continuum
8
30 Materials and Methods
31 Study Site
Bakun Hydroelectric Reservoir is a man-made reservoir which is located 60 km
west of Belaga Sarawak Malaysia (Figure 1) The dam was formed after the
impoundment of Balui River The reservoir has a catchment area of 14750 km2 and a total
capacity 43800000 m3 with a surface area of 695 km2 The dam is the second tallest
concrete-faced rockfill dam in the world
Three sampling stations namely stations 1 2 and 3 was selected in the reservoir
Station 1 is at the inundated estuary of the Linau River Station 2 is at the inundated Balui
River and Station 3 is located in the inundated Balui River as well but nearer to the dam
At each station sampling was conducted at 6 levels namely the subsurface 10m 20m
30m 4Om and 50m depths The coordinates of Bakun dam is at longitude 02deg45 23N and
latitude 114deg0347E The coordinates of every sampling station were recorded by the
Global Positioning System (GARMIN GPSMAP 62S) (Table 1) Sampling was carried
out twice the first sampling was from 21 SI August to 27th August 2015 and the second
sampling was 5th November to 11 th November 2015
9
i
EAST MALAYSIA
o
I
-I River I
-I Flooded Area
Station
0 Dam
kill I
Figure 1 Location of the three sampling stations at Bakun Reservoir
Table 1 Coordinates and locations of sampling stations
Station Coordinates Location
N 02deg 39 322 E 114deg 03 295 Estuary of Linau River
2 N 02deg 43 344 E 114deg 01 442 Balui River
3 N 02deg 43 4135 E 114deg 03 340 Further downstream of Balui River
10
32 Water samples
The water samples were taken using Van Dorn water sampler at all three stations
and were taken at 6 different depths which are the subsurface (02m) 10m 20m 30m 40m
and 5Om At each station three replicates of water samples were taken back for laboratory
analysis Water samples were kept in 2 L polyethylene water bottles that has been acid
washed and were stored in cooler box filled with ice All samples were taken to the
laboratory for further analysis
33 Water quality parameters measured in-situ
Temperature dissolved oxygen (DO) pH electrical conductivity total dissolved
solids (TDS) and turbidity were taken using YSI Multiparameter Water Quality 6920 V2
The depths of each station were measured using depth finder Water transparency was also
measured using secchi disc at each station
34 Water quality parameters analysed ex-situ
341 Biochemical oxygen demand in five days (BODs)
BODs were determined by filling water samples into 300 ml BOD bottles DO
readings of the water samples were measured from the bottles All BOD bottles were
wrapped with aluminum foil to prevent light penetration and were kept in a cooler box for
5 days The initial DO value was recorded as DJ and on the 5th day the DO reading was
recorded as Ds The formula that was used for measuring BODs follows the protocol
outlined by APHA (1998)
11
BOD5 (mglL) = DJ - D5
Where DJ = Initial DO of sample immediately after preparation (mglL)
D5 = DO value after 5 days incubation at 25degC (mglL)
342 Total suspended solids (TSS)
Total suspended solids were analyzed using standard method APHA (1998) For
TSS analysis there was pre-fieldtrip sampling method and post-fieldtrip method For preshy
fieldtrip method glass fibre filter paper (GFIC 47 nun diameter 045 Ilm membrane) were
soaked in distilled water Each filter paper is placed on a piece of aluminum foil and was
dried in the oven at 103degC - 105degC overnight Filter paper then was allowed to cool for 10
minutes before weighing it using an analytical balance (ACCULAB ALC - 210) The
initial weight was recorded For post-fieldtrip method the glass fibre paper was placed on
the inter-plate of the filter funnel using a pair of forceps A known volume of water
samples was filtered using a vacuum pump After that filter paper was removed from the
filtration funnel and was placed back into the aluminum foil Filter paper was dried in the
oven at 103degC - 105degC overnight (APHA 1998) Filter paper was then taken out of the
oven and allowed to cool until room temperature before weighing The final reading of the
filtered glass fibre paper was recorded and TSS was calculated using the formula
w -wTSS (mglL) = J I
V
Where W = Initial weight of filter paper
WJ = Final weight of filter paper
V = Volume of water samples filtered (L)
12
4 Chlorophyll-a
The concentration of chlorophyll-a In the water samples were analyzed using
staDdard method APHA (1998) For chlorophyll-a analysis water samples were filtered
using vacuum pump Filter paper containing chlorophyll-a was taken from the vacuum
pump for analysis The samples were grinded by using a grinder and 5 - 6 mL of 90
acetone was added into the mortar Samples were grinded for about 5 minutes and all
materials in the mortar were placed into a capped test tube Ninety percent acetone was
added into the test tube to make up the volume to 10mL Test tube was folded with
aluminum foil and was placed in the refrigerator for 4 - 18 hours to facilitate complete
extraction of the pigments The liquid extracted was transferred into the centrifuge tube
The samples were placed into a centrifuge for about 10 minutes under 3000 rpm Optical
density was determined using spectrophotometer at wavelength of 750 nm 664 run 647
am and 630 nm Each extinctions for small turbidity blank was corrected by subtracting
750 nm from 664 nm and 630 run absorptions
The concentration of chlorophyll-a in the extract of the pigment after correction was
calculated using
Where E = the absorption in the respective wavelength
After determining the concentration of the chlorophyll-a in the extract the amount of
cblorophyll-a in the pigment per unit volume of water filtered was calculated as follows
13
Ca(v)Chlorophyll-a (Jg IL) = - shyv
Where Co = Chlorophyll-a pigment concentration in JgmL
v = Volume ofacetone in mL
v = Volume of samples in L
344 Ammonia-nitrogen (NH3-N)
For ammonia-nitrogen (NH3-N) the concentration was determined using standard
method 8038 Nessler Method (HACH 2000) A 25 mL prepared sample and 25 mL of
deionized water were filled into a separate 25 mL mixing graduated cylinder Three drops
of Mineral Stabilizer were added to both of the cylinders The cylinders were inverted
several times to mix the content After that 1 mL of Nessler reagent was pipetted into both
of the cylinders and the cylinders were inverted several times to mix the content A one-
minute reaction was started Both the solutions were poured into a square sample cell A
yellow colour formation will indicate the presence of ammonia When the timer expired
the blank was inserted into the square sample cell with the fill line facing the right The
reading at 425 run was zeroed The prepared sample was inserted into the cell holder of
Spectrophotometer DR 2800 (HACH 2000) with the fill line facing right and the reading
displayed was recorded
345 Nitrate (NO)-)
For nitrate analysis the concentration was determined using standard method 8192
Cadmium Reduction Method (HACH 2000) The sample was filled until the 15 mL mark
of a 25 mL graduated measuring cylinder The content of one Nitra Ver6 Nitrate Reagent
Pillow Powder was added into the cylinder and capped with a stopper The cylinder was
14
DECLARATION OF AUTHORSHIP
I Willie Koh declare that the final year project report entitled
Water Quality at Bakun HEP Reservoir Belaga Sarawak
and the work presented in the report are both my own and have been generated by me as
the result of my own original research I confirm that
bull this work was done wholly or mainly while in candidature for a research degree at
bull this University
bull where I have made corrections based on suggestion by supervisor and examiners
bull this has been clearly stated
bull where I have consulted the published work of others this IS always clearly
attributed
bull where I have quoted from the work of others the source is always given With the
bull exception of such quotations this report is entirely my own work
bull I have acknowledged all main sources of help
bull where the thesis is based on work done by myself jointly with others I have made
bull clear exactly what was done by others and what I have contributed myself
bull none of this work has been published before submission
Signed
Aquatic Resource Science and Management Department of Aquatic Science Faculty of Resource Science and Technology Universiti Malaysia Sarawak (UNIMAS)
I
ACKNOWLEDGMENT
My utmost gratitude and thanks to my supervisor Professor Dr Lee Nyanti Janti
ak Chukong for his valuable advice suggestions guidance constructive criticisms and
commitment from the start of this research until the final submission of this thesis
Besides that a special thanks to my co-supervisor Associate Professor Dr Ling Teck Vee
on the guidance and support
I would also like to express my appreciation to the staff of the Department of
Aquatic Science Mr Benedict ak Samling and Mr Richard Toh for their friendly help
and facilitation during the field work and laboratory work Not forgetting my fellow peers
who helped me and for their valuable support Also special thanks to my seniors Angie
Sapis and Ahmad Aklunal Atan for the precious advice Without their kind support and
technical assistance it would not be an easy task to complete this study Also warmest
regards and thanks to Mr Laing and his family for providing us a comfortable
accommodation during our field work in Bakun
Special thanks also goes to Sarawak Energy Berhand for the financial assistance in
this study through the research grant no GL (F07)SEB4A12013 (24)
Finally my family members are highly acknowledged for their understanding and
never ending support To those who indirectly contribute to this research your kindness is
greatly appreciated All praises to God for the strength and opportunity for completing this
thesis Without his mercy I may not be able to go through the tough times in the course of
this study
II
i
Water Quality at Bakun HEP Reservoir Belaga Sarawak
Abstract
Since the water supply at Bakun Hydroelectric Dam reached its full supply level only one previous study has been done during the filling phase of the dam which was 3 years and 10 months earlier than this study As water in the reservoir is very important for the aquatic organisms in the reservoir and downstream of the dam a study was conducted at 3 stations to determine the selected water quality parameters 5 years 6 months after impoundment started At each station water in triplicate samples were collected at 6 levels which is the subsurface at 10m 20m 30m 40m and 50m depth Results showed that thermocline occurred at 3m to 10m depth at all stations DO at the subsurface (499 - 610 mgL) dropped drastically to anoxic level starting from 2m to 10m depth at all stations Water conductivity and turbidity increases while pH decreased as depth increased The highest chlorophyll-a (1168 J-lgL) was recorded at 10m depth with positive correlation with turbidity Increasing levels of ammonia-nitrogen (00533 - 06400 mgL) total suspended solids (330 - 6306 mgL) and five-day biochemical oxygen demand (186 - 430 mgL) were observed while depth increases Nitrate (001 - 022 mgL) nitrite (00020 - 01170 mgL) silica (039 - 154 mgL) and orthophosphate (00900 - 17067 mgL) showed different variations with depth This present study showed that the water quality at Bakun Hydroelectric Dam was improving and still changing compared to the previous study during the filling phase and has not stabilize even after 5 years 6 months after impoundment started
Keywords hydroelectric dam turbidity water quality nutrients
Abstrak
Sejak bekalan air di Empangan Hidroelektrik Bakun mencapai tahap penuh hanya satu kajian telah dijalankan semasa fasa pengisian iaitu 3 tahun dan 10 bulan lebih awal daripada kajian ini Disebabkan air di dalam empangan adalah sangat penting untuk organisma akuatik di dalam empangan dan bawah empangan satu kajian telah dijalankan di 3 stesen untuk mengenalpasti parameter kualiti air 5 tahun selepas penakungan bermula Di setiap stesen air telah diambil sebanyak tiga kali daripada 6 tahap iaitu subpermukaan 10m 20m 30m 40m dan 50m Hasil kajian menunjuk perbentukan termoklin pada kedalaman dari 3m ke 10m di semua stesen DO di subpermukaan (499shy610 mglL) menurun dengan drastik kepada tahap anoksik bermula pada kedalaman 2m ke 10m di semua stesen Konduktiviti air dan kekeruhan meningkat dan pH menurun dengan kedalaman Klorofil-a paling tinggi (1168 pgIL) adalah pada kedalaman 10m dan berkorelasi positijdengan kekeruhan air Peningkatan tahap ammonia-nitrogen (00533 shy06400 mgIL) jumlah pepejal terampai (330 - 6306 mgIL) dan keperluan oksigen biokimia selepas lima hari (186 - 430 mglL) meningkat apabila kedalaman meningkat Nitrat (001 - 022 mgIL) nitrit (00020 - 01170 mgIL) silika (039 - 154 mglL) dan ortofosfat (00900 - 17067 mglL) menunjukkan variasi yang berbeza dengan kedalaman Kajian ini menunjukkan bahawa kualiti air di Empangan Hidroelektrik Bakun bertambah baik dan masih berubah berbanding dengan kajian semasa fasa pengisian dan belum lagi staNI selepas 5 tahun dan 6 bulan sejak penakungan bermula
Kata kunci empangan hidroelektrik kekeruhan air kualiti air nutrien
III
Pusat Khidmat Maklumal Akadtmi UNIVEftSm MALAYSIA SAKAWA
TABLE OF CONTENTS
Declaration of Authorship
Acknowledgement
Abstract
Abstrak
Table of Contents
List of Figures
List of Tables
List of Abbreviations
10 Introduction
20 Literature Review
21 Reservoir
22 Water Quality
221 Temperature
222 Dissolved Oxygen (DO)
223 pH
224 Nutrients
23 Impact of Hydroelectric Dams on Water Quality
30 Materials and Methods
31 Study Site
32 Water Samples
33 Water Quality Parameters Measured In-situ
34 Water Quality Parameters Analysed Ex-situ
341 Biological Oxygen Demand (BODs)
342 Total Suspended Solids (TSS)
343 Chlorophyll-a
344 Ammonia-Nitrogen (NH3-N)
345 Nitrate (N03-)
346 Nitrite (N02-)
347 Orthophosphate (P043-)
348 Silica (Si04)
35 Statistical Analyses
Page
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VII
VIII
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IV
18 40 Results
41 Water Quality Parameters Measured In-situ 18
411 Water Depth and Transparency 18
412 Temperature 18
413 Ph 23
414 Water Turbidity 26
415 Water Conductivity 28
416 Dissolved Oxygen (DO) 31
42 Water Quality Parameters Measured Ex-situ 35
421 Chlorophyll-a 35
422 Biochemical Oxygen Demand in Five Days (BOD5) 37
423 Nitrate (NOf) 39
424 Nitrite (N02-) 42
425 Ammonia-Nitrogen (NH3-N) 44
426 Silica (Si04) 46
427 Orthophosphate (P043-) 48
428 Total Suspended Solids (TSS) 50
50 Discussion 52
51 Water Parameters Measured In-situ 52
52 Water Parameters Measured Ex-situ 57
60 Summary 63
70 Conclusion 65
80 References 66
90 Appendices 71
v
I
Figure
Figure 1
Figure 2
Figure 3
Figure 4
Figure 5
Figure 6
Figure 7
Figure 8
Figure 9
Figure 10
Figure 11
Figure 12
Figure 13
Figure 14
Figure 15
Figure 16
Figure 17
Figure 18
Figure 19
Figure 20
Figure 21
Figure 22
Figure 23
Figure 24
Figure 25
Figure 26
Figure 27
Figure 28
Figure 29
Figure 30
Figure 31
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LIST OF FIGURES
Title Page
The location of sampling stations at Bakun Dam Sarawak 10
19
Temperature values in November 2015
Temperature values in August 2015
21
Temperature profile in August 2015 22
Temperature profile in November 2015 23
PH values in August 2015 24
PH values in November 2015 25
Turbidity values in August 2015 27
Turbidity values in November 2015 28
Water conductivity values in August 2015 29
Water conductivity values in November 2015 30
Dissolved oxygen (DO) values in August 2015 32
Dissolved oxygen (DO) values in November 2015 33
Dissolved oxygen (DO) profile in August 2015 34
Dissolved oxygen (DO) profile in November 2015 34
Chlorophyll-a values in August 2015 36
Chlorophyll-a values in November 2015 37
BODs values in August 2015 38
BODs values in November 2015 39
Nitrate-N values in August 2015 41
Nitrate-N values in November 2015 41
Nitrite-N values in August 2015 43
Nitrite-N values in November 2015 43
Ammonia-N values in August 2015 45
Ammonia-N values in November 2015 45
Silica values in August 2015 47
Silica values in November 2015 47
Orthophosphate values in August 2015 49
Orthophosphate values in November 2015 49
TSS values in August 2015 51
TSS values in November 2015 51
VI
LIST OF TABLES
Table Title Page
Table 1 Coordinates and locations of sampling stations 10
Table 2 Water depth and transparency values in August 2015 18
Table 3 Classification of water quality parameters according to NWQS 64
VII
LIST OF ABBREVIATIONS
degC Degree Celsius
lm Micrometre
BOD Biological Oxygen Demand
DO Dissolved Oxygen
km2 Kilometre Square
3m Cubic Metre
mgL Milligram per litre
mL Millilitre
L Litre
nm Nanometre
mm Millimetre
pH Potential of Hydrogen
N Nitrogen
N02- Nitrite
N03- Nitrate
P04 3- Orthophosphate
Si04 Silica
NH3-N Ammonia-Nitrogen
TSS Total Suspended Solids
TDS Total Dissolved Solids
GPS Global Positioning System
VIII
10 Introduction
Hydroelectric dams have been constructed worldwide to provide an alternative
energy source as petroleum in the world is depleting and is not renewable Hence
impoundment started around the world to collect water bodies to act as a reservoir
Reservoirs formed by impoundment they will undergo great changes in water
quality (Chapman 1996) This was observed in tropical reservoirs such as Feitsui
Reservoir in Taiwan (Chang and Wen 1997) and Lake Brokopondo in Surinam (Van der
Heide 1978) and also temperate reservoirs such as Butgenbuch Reservoir in Belgium
(Lourantou et aI 2007) and Bureye Reservoir in Russia (Shesterkin 2008) This happens
because of the impact of inundated soil and vegetation including the standing forest on the
water quality such as pH level and dissolved oxygen concentration (Van der Heide 1978
Shesterkin 2008) which is essential for aquatic life
In Malaysia hydroelectric dams have been constructed to meet the energy needs
and security Among the hydroelectric dams that have been built in Sarawak is the Bakun
Hydroelectric Dam Construction of the dam started in 2002 It is located about sixty
kilometers from the town of Belaga and is situated on the Balui River Bakun
Hydroelectric Dam is the largest hydropower project in Malaysia that can produce up to
2400 MW of electricity (httpwwwsarawakenergycomrny)Itis the second highest
concrete faced rockfill dam in the world with an area of 695 square kilometers and a height
of 207 meters (httpwwwsarawakenergycomrny) Research on the characteristics of
physico-chemical water quality at Bakun Dam has been conducted by Nyanti (2012)
However it was conducted during the filling phase of the hydroelectric dam which is
fifteen months after impoundment has started Since then there has been no publishing
literature on the characteristics of the water quality
1
Hence the goal of this study is to obtain detailed information on the physicoshy
chemical water properties of the Bakun Hydroelectric Dam 3 years and 7 months after it
has reached its full supply level Therefore the objectives of this study were
(i) To determine the water quality at six depths at three stations in the
reservOIr
(ii) Compare the characteristics of the water quality among the depths and
stations and
(iii) Determine the changes in water quality characteristics 5 years 6 months
after the dam was impounded
2
jl - - I
20 Literature Review
21 Reservoir
According to Pawar amp Shembekar (2012) water is important and it is the most
abundant resource in the world which man has used for decades Water covers about 70
of the earths surface but only 27 of the total amount is freshwater of which 1 is iceshy
free water in the rivers lakes and atmosphere as biological water It is believed that only
0001 92 of the total water on earth is available for human use (Pawar amp Shembekar
2012) Hence reservoirs are created in order to provide domestic water supply generation
of electricity and aquaculture In Malaysia 63 large reservoirs with a total storage of 25
billion m3 have been constructed (Makhlough 2008)
Water quality in reservoirs is greatly affected by the composition of plant materials
that were submerged during the inundation process In a study done by Ling (2012) water
in the Batang Ai reservoir contains high sulfide concentrations especially at inundated
areas Besides that Nyanti (2012) also reported that the anoxic condition and the acidic
condition in Bakun Dam is due to the decomposition of submerged carbonaceous
materials
Additionally human activities in and around reservoirs and the physical and
chemical properties of water will be affected (Mustapha 2008) Precipitation evaporation
and ground movement can also affect water quality In Batang Ai reservoir the dissolved
oxygen was reported to be lower due to nearby cage aquaculture as it is consumed by
microorganisms in the decomposition of organic matter (Ling 2012)
22 Water quality
Water quality in a reservoir is the physical and chemical limnology of a reservoir
(Sidnei 1992) and includes all physical chemical and biological aspects of water that
3
influence the beneficial usage of water (Mustapha 2008) In reservoirs water quality
deterioration usually comes from excessive nutrient inputs eutrophication acidification
heavy metal contamination organic pollution and obnoxious fishing practices (Mustapha
2008)
Therefore water quality is an important indicator of the ecological status of a
reservoir It is reported that the significant lower dissolved oxygen is recorded due to
higher turbidity and increased suspended solids which affect the dissolution of oxygen
which is brought in by the flood that occurred in Oyun Reservoir (Mustapha 2008)
Additionally in a study done at Bakun Dam turbidity is affected by the suspended solids
from eroded soils from the logging activities in the watershed upstream from the north of
the reservoir (Nyanti 2012)
221 Temperature
Temperature is very important to a reservoir as it affects chemical and biological
activities of aquatic organisms (Sangpal 2011) In a reservoir when the upper layer and
the lower layer have great variation in temperature thermocline will occur Thermal
stratification in deep reservoir is an important natural process which gives significant
effects on water quality The production of ammonia sulphide and algal nutrients are
dependent on the changes in water temperature which subsequently affects the water
quality (Baharim 2011) Besides that vertical distribution and change in water
temperature can affect productivity of the natural organisms in the reservoirs However
the effect varies from reservoir to reservoir According to Li amp Xu (1995) thermocline is
common in reservoirs and usually occurs at the depth of 8m to 23m In a study done by
Nyanti (2012) water temperature in Bakun reservoir was reported to undergo thermocline
as depth increased from subsurface to 18m
4
l I
Pusat Khidmat Maldumat Akadfmil UN nsmMALAYSIA SARAWAI~
222 Dissolved Oxygen (DO)
DO is a very essential environmental factor that affects the entire production of a
reservoir and it is also an important indicator of water quality health of reservoir and also
ecological status as it is used for respiration and in biological and chemical reactions
(Mustapha 2008)
DO fluctuate from reservOIr to reservOIr and it is usually affected by
photosynthesis respiration and diel fluctuation In a study done by Ling (2012) it was
reported that the DO is higher at 05m depth at a11 stations in Batang Ai reservoir ranging
from 47 to 87 mgL due to the high phytoplankton photosynthesis rate An example of
diel fluctuation is shown in Kontagora reservoir where the DO is higher during the dry
season than the rainy season (Ibrahim 2009) This shows that the fluctuation also depends
on temperature depth wind and amount of biological activities such as decomposition In
Bakon Dam DO is high at the subsurface but dropped drastically until anoxic level at
depth 2 - 4m 2 years after impoundment and this is mainly due to the decomposition of
organic matter (Nyanti 2012)
223 pH
pH that is suitable for optimal production for inland waters should be about 65 to
85 (Ibrahim 2009) However changes in pH can affect the transfer of nutrients and affect
the condition ofwater quality (Li amp Xu 1995)
Fluctuations in pH can be caused by the photosynthesis process of phytoplanktons
as was reported in Batang Ai reservoir where all pH value was above 7 (Ling 2012)
Carbon dioxide produced by photosynthesis process will alter the pH of water as carbonic
acid will be formed when carbon dioxide reacts with water (Sangpal 2011)
5
Acidic effects in reservoirs can be caused by the transfer of cooler water from other
tributaries where the water is denser and lower in pH Nyanti (2012) reported the pH value
at Bakundam were all acidic ranging from 517-592 and the overall trend of pH in Bakun
dam decreases from upstream towards the dam (Nyanti et aI 2012)
224 Nutrients
Reservoirs are often have higher chances of getting higher element loading
compared to natural lakes as they have greater catchment area and high inflow rates
(Pawar amp Shembekar 2012) The concentration of nutrients varies from reservoir to
reservoir due to the differences in soil and vegetation in the catchment area (Li amp Xu
1995) Nutrients such as nitrates phosphates silicates and iron are important nutrients
required for aquatic growth but may also cause eutrophication and water quality problems
(Li amp Xu 1995) Eutrophication can occur easily in reservoir due to high input of nutrients
into the water and water quality of reservoir will be affected giving rise to unpleasant taste
and odour and affects the dissolution of other gases especially dissolved oxygen
(Mustapha 2008) According to Nyanti (2012) strong rotten egg smell discovered in
Bakun dam indicates high volume of hydrogen sulfide This observation is also supported
by Lourantou (2007) where an irritating odour smell occurs at a reservoir in Belgium
Nutrients input can also be affected by weather and season where nitrate was recorded at
higher values in Ujjani reservoir during post-monsoon season This may be caused by the
oxidation of nitrifying bacteria and biological nitrification Sulphate concentrations in the
dam were very high in both pre and post-monsoon which were probably caused by the
mineral rocks anthropogenically added and also by rain (Sangpal 2011) The phosphate
levels were found to be lower during the pre-monsoon and higher during the postshy
6
monsoon Phosphate leads to eutrophication that can cause unpleasant taste and odour to
the water (Sangpal 2011)
23 Impacts of hydroelectric dams on water quality
Hydroelectric dam has a direct impact to the water quality as it uses the flow rate of
a water course to produce electricity The building of hydroelectric dams has direct impact
towards the chemical thermal and physical parameters of the water body (Bunea 2012)
According to a study done by Bunea (2012) hydroelectric dams have relatively low DO
concentration mostly lower than 50 mglL because of the organic sediments that are left at
the bottom of the reservoir bottom during the initial filing Organic substances left at the
bottom of the reservoir bottom floor will absorb oxygen from the water in order to
decompose producing hydrogen sulphide carbon dioxide and methane (Bunea 2012)
Due to damming for hydroelectric generation water in a reservoir will undergo
stagnation which will lead to thermal stratification (Bunea 2012) According to a study
done by Elci (2008) thermal stratification of the reservoir involves the higher temperature
at the surface and lower temperatures at the bottom which suggests that thermal energy is
very slowly transferred to the bottom layers of the water body Thermal stratification act as
a barrier to re train mixing of the water column This causes an uneven concentration of
nutrients lack of light for photosynthesis at the hypolimnion and the water column may
become anoxic (Elci 2008)
Hydroelectric dams also greatly reduces the water self-purification capacity
According to Wei et al (2009) water self-purification mechanisms are affected by the
physical chemical and biotic processes in a reservoir However dam construction affects
all of the processes as the flow regime water quality and biotic community in the river In
other words dams slow down the river flow capacity block the river continuum and raise
7
water temperature which decreases the water self-purification capacity (Wei et aI 2009)
In a study done in China by Wei et al (2009) it is recorded that the Manwan-Dachaosan
dam has higher ammonia-nitrogen concentration due to the decreased water selfshy
purification capacity as compared to the pre-dam period This suggests that damming has
severely decreased the water self-purification capacity as it blocked the river continuum
8
30 Materials and Methods
31 Study Site
Bakun Hydroelectric Reservoir is a man-made reservoir which is located 60 km
west of Belaga Sarawak Malaysia (Figure 1) The dam was formed after the
impoundment of Balui River The reservoir has a catchment area of 14750 km2 and a total
capacity 43800000 m3 with a surface area of 695 km2 The dam is the second tallest
concrete-faced rockfill dam in the world
Three sampling stations namely stations 1 2 and 3 was selected in the reservoir
Station 1 is at the inundated estuary of the Linau River Station 2 is at the inundated Balui
River and Station 3 is located in the inundated Balui River as well but nearer to the dam
At each station sampling was conducted at 6 levels namely the subsurface 10m 20m
30m 4Om and 50m depths The coordinates of Bakun dam is at longitude 02deg45 23N and
latitude 114deg0347E The coordinates of every sampling station were recorded by the
Global Positioning System (GARMIN GPSMAP 62S) (Table 1) Sampling was carried
out twice the first sampling was from 21 SI August to 27th August 2015 and the second
sampling was 5th November to 11 th November 2015
9
i
EAST MALAYSIA
o
I
-I River I
-I Flooded Area
Station
0 Dam
kill I
Figure 1 Location of the three sampling stations at Bakun Reservoir
Table 1 Coordinates and locations of sampling stations
Station Coordinates Location
N 02deg 39 322 E 114deg 03 295 Estuary of Linau River
2 N 02deg 43 344 E 114deg 01 442 Balui River
3 N 02deg 43 4135 E 114deg 03 340 Further downstream of Balui River
10
32 Water samples
The water samples were taken using Van Dorn water sampler at all three stations
and were taken at 6 different depths which are the subsurface (02m) 10m 20m 30m 40m
and 5Om At each station three replicates of water samples were taken back for laboratory
analysis Water samples were kept in 2 L polyethylene water bottles that has been acid
washed and were stored in cooler box filled with ice All samples were taken to the
laboratory for further analysis
33 Water quality parameters measured in-situ
Temperature dissolved oxygen (DO) pH electrical conductivity total dissolved
solids (TDS) and turbidity were taken using YSI Multiparameter Water Quality 6920 V2
The depths of each station were measured using depth finder Water transparency was also
measured using secchi disc at each station
34 Water quality parameters analysed ex-situ
341 Biochemical oxygen demand in five days (BODs)
BODs were determined by filling water samples into 300 ml BOD bottles DO
readings of the water samples were measured from the bottles All BOD bottles were
wrapped with aluminum foil to prevent light penetration and were kept in a cooler box for
5 days The initial DO value was recorded as DJ and on the 5th day the DO reading was
recorded as Ds The formula that was used for measuring BODs follows the protocol
outlined by APHA (1998)
11
BOD5 (mglL) = DJ - D5
Where DJ = Initial DO of sample immediately after preparation (mglL)
D5 = DO value after 5 days incubation at 25degC (mglL)
342 Total suspended solids (TSS)
Total suspended solids were analyzed using standard method APHA (1998) For
TSS analysis there was pre-fieldtrip sampling method and post-fieldtrip method For preshy
fieldtrip method glass fibre filter paper (GFIC 47 nun diameter 045 Ilm membrane) were
soaked in distilled water Each filter paper is placed on a piece of aluminum foil and was
dried in the oven at 103degC - 105degC overnight Filter paper then was allowed to cool for 10
minutes before weighing it using an analytical balance (ACCULAB ALC - 210) The
initial weight was recorded For post-fieldtrip method the glass fibre paper was placed on
the inter-plate of the filter funnel using a pair of forceps A known volume of water
samples was filtered using a vacuum pump After that filter paper was removed from the
filtration funnel and was placed back into the aluminum foil Filter paper was dried in the
oven at 103degC - 105degC overnight (APHA 1998) Filter paper was then taken out of the
oven and allowed to cool until room temperature before weighing The final reading of the
filtered glass fibre paper was recorded and TSS was calculated using the formula
w -wTSS (mglL) = J I
V
Where W = Initial weight of filter paper
WJ = Final weight of filter paper
V = Volume of water samples filtered (L)
12
4 Chlorophyll-a
The concentration of chlorophyll-a In the water samples were analyzed using
staDdard method APHA (1998) For chlorophyll-a analysis water samples were filtered
using vacuum pump Filter paper containing chlorophyll-a was taken from the vacuum
pump for analysis The samples were grinded by using a grinder and 5 - 6 mL of 90
acetone was added into the mortar Samples were grinded for about 5 minutes and all
materials in the mortar were placed into a capped test tube Ninety percent acetone was
added into the test tube to make up the volume to 10mL Test tube was folded with
aluminum foil and was placed in the refrigerator for 4 - 18 hours to facilitate complete
extraction of the pigments The liquid extracted was transferred into the centrifuge tube
The samples were placed into a centrifuge for about 10 minutes under 3000 rpm Optical
density was determined using spectrophotometer at wavelength of 750 nm 664 run 647
am and 630 nm Each extinctions for small turbidity blank was corrected by subtracting
750 nm from 664 nm and 630 run absorptions
The concentration of chlorophyll-a in the extract of the pigment after correction was
calculated using
Where E = the absorption in the respective wavelength
After determining the concentration of the chlorophyll-a in the extract the amount of
cblorophyll-a in the pigment per unit volume of water filtered was calculated as follows
13
Ca(v)Chlorophyll-a (Jg IL) = - shyv
Where Co = Chlorophyll-a pigment concentration in JgmL
v = Volume ofacetone in mL
v = Volume of samples in L
344 Ammonia-nitrogen (NH3-N)
For ammonia-nitrogen (NH3-N) the concentration was determined using standard
method 8038 Nessler Method (HACH 2000) A 25 mL prepared sample and 25 mL of
deionized water were filled into a separate 25 mL mixing graduated cylinder Three drops
of Mineral Stabilizer were added to both of the cylinders The cylinders were inverted
several times to mix the content After that 1 mL of Nessler reagent was pipetted into both
of the cylinders and the cylinders were inverted several times to mix the content A one-
minute reaction was started Both the solutions were poured into a square sample cell A
yellow colour formation will indicate the presence of ammonia When the timer expired
the blank was inserted into the square sample cell with the fill line facing the right The
reading at 425 run was zeroed The prepared sample was inserted into the cell holder of
Spectrophotometer DR 2800 (HACH 2000) with the fill line facing right and the reading
displayed was recorded
345 Nitrate (NO)-)
For nitrate analysis the concentration was determined using standard method 8192
Cadmium Reduction Method (HACH 2000) The sample was filled until the 15 mL mark
of a 25 mL graduated measuring cylinder The content of one Nitra Ver6 Nitrate Reagent
Pillow Powder was added into the cylinder and capped with a stopper The cylinder was
14
ACKNOWLEDGMENT
My utmost gratitude and thanks to my supervisor Professor Dr Lee Nyanti Janti
ak Chukong for his valuable advice suggestions guidance constructive criticisms and
commitment from the start of this research until the final submission of this thesis
Besides that a special thanks to my co-supervisor Associate Professor Dr Ling Teck Vee
on the guidance and support
I would also like to express my appreciation to the staff of the Department of
Aquatic Science Mr Benedict ak Samling and Mr Richard Toh for their friendly help
and facilitation during the field work and laboratory work Not forgetting my fellow peers
who helped me and for their valuable support Also special thanks to my seniors Angie
Sapis and Ahmad Aklunal Atan for the precious advice Without their kind support and
technical assistance it would not be an easy task to complete this study Also warmest
regards and thanks to Mr Laing and his family for providing us a comfortable
accommodation during our field work in Bakun
Special thanks also goes to Sarawak Energy Berhand for the financial assistance in
this study through the research grant no GL (F07)SEB4A12013 (24)
Finally my family members are highly acknowledged for their understanding and
never ending support To those who indirectly contribute to this research your kindness is
greatly appreciated All praises to God for the strength and opportunity for completing this
thesis Without his mercy I may not be able to go through the tough times in the course of
this study
II
i
Water Quality at Bakun HEP Reservoir Belaga Sarawak
Abstract
Since the water supply at Bakun Hydroelectric Dam reached its full supply level only one previous study has been done during the filling phase of the dam which was 3 years and 10 months earlier than this study As water in the reservoir is very important for the aquatic organisms in the reservoir and downstream of the dam a study was conducted at 3 stations to determine the selected water quality parameters 5 years 6 months after impoundment started At each station water in triplicate samples were collected at 6 levels which is the subsurface at 10m 20m 30m 40m and 50m depth Results showed that thermocline occurred at 3m to 10m depth at all stations DO at the subsurface (499 - 610 mgL) dropped drastically to anoxic level starting from 2m to 10m depth at all stations Water conductivity and turbidity increases while pH decreased as depth increased The highest chlorophyll-a (1168 J-lgL) was recorded at 10m depth with positive correlation with turbidity Increasing levels of ammonia-nitrogen (00533 - 06400 mgL) total suspended solids (330 - 6306 mgL) and five-day biochemical oxygen demand (186 - 430 mgL) were observed while depth increases Nitrate (001 - 022 mgL) nitrite (00020 - 01170 mgL) silica (039 - 154 mgL) and orthophosphate (00900 - 17067 mgL) showed different variations with depth This present study showed that the water quality at Bakun Hydroelectric Dam was improving and still changing compared to the previous study during the filling phase and has not stabilize even after 5 years 6 months after impoundment started
Keywords hydroelectric dam turbidity water quality nutrients
Abstrak
Sejak bekalan air di Empangan Hidroelektrik Bakun mencapai tahap penuh hanya satu kajian telah dijalankan semasa fasa pengisian iaitu 3 tahun dan 10 bulan lebih awal daripada kajian ini Disebabkan air di dalam empangan adalah sangat penting untuk organisma akuatik di dalam empangan dan bawah empangan satu kajian telah dijalankan di 3 stesen untuk mengenalpasti parameter kualiti air 5 tahun selepas penakungan bermula Di setiap stesen air telah diambil sebanyak tiga kali daripada 6 tahap iaitu subpermukaan 10m 20m 30m 40m dan 50m Hasil kajian menunjuk perbentukan termoklin pada kedalaman dari 3m ke 10m di semua stesen DO di subpermukaan (499shy610 mglL) menurun dengan drastik kepada tahap anoksik bermula pada kedalaman 2m ke 10m di semua stesen Konduktiviti air dan kekeruhan meningkat dan pH menurun dengan kedalaman Klorofil-a paling tinggi (1168 pgIL) adalah pada kedalaman 10m dan berkorelasi positijdengan kekeruhan air Peningkatan tahap ammonia-nitrogen (00533 shy06400 mgIL) jumlah pepejal terampai (330 - 6306 mgIL) dan keperluan oksigen biokimia selepas lima hari (186 - 430 mglL) meningkat apabila kedalaman meningkat Nitrat (001 - 022 mgIL) nitrit (00020 - 01170 mgIL) silika (039 - 154 mglL) dan ortofosfat (00900 - 17067 mglL) menunjukkan variasi yang berbeza dengan kedalaman Kajian ini menunjukkan bahawa kualiti air di Empangan Hidroelektrik Bakun bertambah baik dan masih berubah berbanding dengan kajian semasa fasa pengisian dan belum lagi staNI selepas 5 tahun dan 6 bulan sejak penakungan bermula
Kata kunci empangan hidroelektrik kekeruhan air kualiti air nutrien
III
Pusat Khidmat Maklumal Akadtmi UNIVEftSm MALAYSIA SAKAWA
TABLE OF CONTENTS
Declaration of Authorship
Acknowledgement
Abstract
Abstrak
Table of Contents
List of Figures
List of Tables
List of Abbreviations
10 Introduction
20 Literature Review
21 Reservoir
22 Water Quality
221 Temperature
222 Dissolved Oxygen (DO)
223 pH
224 Nutrients
23 Impact of Hydroelectric Dams on Water Quality
30 Materials and Methods
31 Study Site
32 Water Samples
33 Water Quality Parameters Measured In-situ
34 Water Quality Parameters Analysed Ex-situ
341 Biological Oxygen Demand (BODs)
342 Total Suspended Solids (TSS)
343 Chlorophyll-a
344 Ammonia-Nitrogen (NH3-N)
345 Nitrate (N03-)
346 Nitrite (N02-)
347 Orthophosphate (P043-)
348 Silica (Si04)
35 Statistical Analyses
Page
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11
12
13
14
14
15
16
16
17
IV
18 40 Results
41 Water Quality Parameters Measured In-situ 18
411 Water Depth and Transparency 18
412 Temperature 18
413 Ph 23
414 Water Turbidity 26
415 Water Conductivity 28
416 Dissolved Oxygen (DO) 31
42 Water Quality Parameters Measured Ex-situ 35
421 Chlorophyll-a 35
422 Biochemical Oxygen Demand in Five Days (BOD5) 37
423 Nitrate (NOf) 39
424 Nitrite (N02-) 42
425 Ammonia-Nitrogen (NH3-N) 44
426 Silica (Si04) 46
427 Orthophosphate (P043-) 48
428 Total Suspended Solids (TSS) 50
50 Discussion 52
51 Water Parameters Measured In-situ 52
52 Water Parameters Measured Ex-situ 57
60 Summary 63
70 Conclusion 65
80 References 66
90 Appendices 71
v
I
Figure
Figure 1
Figure 2
Figure 3
Figure 4
Figure 5
Figure 6
Figure 7
Figure 8
Figure 9
Figure 10
Figure 11
Figure 12
Figure 13
Figure 14
Figure 15
Figure 16
Figure 17
Figure 18
Figure 19
Figure 20
Figure 21
Figure 22
Figure 23
Figure 24
Figure 25
Figure 26
Figure 27
Figure 28
Figure 29
Figure 30
Figure 31
-
LIST OF FIGURES
Title Page
The location of sampling stations at Bakun Dam Sarawak 10
19
Temperature values in November 2015
Temperature values in August 2015
21
Temperature profile in August 2015 22
Temperature profile in November 2015 23
PH values in August 2015 24
PH values in November 2015 25
Turbidity values in August 2015 27
Turbidity values in November 2015 28
Water conductivity values in August 2015 29
Water conductivity values in November 2015 30
Dissolved oxygen (DO) values in August 2015 32
Dissolved oxygen (DO) values in November 2015 33
Dissolved oxygen (DO) profile in August 2015 34
Dissolved oxygen (DO) profile in November 2015 34
Chlorophyll-a values in August 2015 36
Chlorophyll-a values in November 2015 37
BODs values in August 2015 38
BODs values in November 2015 39
Nitrate-N values in August 2015 41
Nitrate-N values in November 2015 41
Nitrite-N values in August 2015 43
Nitrite-N values in November 2015 43
Ammonia-N values in August 2015 45
Ammonia-N values in November 2015 45
Silica values in August 2015 47
Silica values in November 2015 47
Orthophosphate values in August 2015 49
Orthophosphate values in November 2015 49
TSS values in August 2015 51
TSS values in November 2015 51
VI
LIST OF TABLES
Table Title Page
Table 1 Coordinates and locations of sampling stations 10
Table 2 Water depth and transparency values in August 2015 18
Table 3 Classification of water quality parameters according to NWQS 64
VII
LIST OF ABBREVIATIONS
degC Degree Celsius
lm Micrometre
BOD Biological Oxygen Demand
DO Dissolved Oxygen
km2 Kilometre Square
3m Cubic Metre
mgL Milligram per litre
mL Millilitre
L Litre
nm Nanometre
mm Millimetre
pH Potential of Hydrogen
N Nitrogen
N02- Nitrite
N03- Nitrate
P04 3- Orthophosphate
Si04 Silica
NH3-N Ammonia-Nitrogen
TSS Total Suspended Solids
TDS Total Dissolved Solids
GPS Global Positioning System
VIII
10 Introduction
Hydroelectric dams have been constructed worldwide to provide an alternative
energy source as petroleum in the world is depleting and is not renewable Hence
impoundment started around the world to collect water bodies to act as a reservoir
Reservoirs formed by impoundment they will undergo great changes in water
quality (Chapman 1996) This was observed in tropical reservoirs such as Feitsui
Reservoir in Taiwan (Chang and Wen 1997) and Lake Brokopondo in Surinam (Van der
Heide 1978) and also temperate reservoirs such as Butgenbuch Reservoir in Belgium
(Lourantou et aI 2007) and Bureye Reservoir in Russia (Shesterkin 2008) This happens
because of the impact of inundated soil and vegetation including the standing forest on the
water quality such as pH level and dissolved oxygen concentration (Van der Heide 1978
Shesterkin 2008) which is essential for aquatic life
In Malaysia hydroelectric dams have been constructed to meet the energy needs
and security Among the hydroelectric dams that have been built in Sarawak is the Bakun
Hydroelectric Dam Construction of the dam started in 2002 It is located about sixty
kilometers from the town of Belaga and is situated on the Balui River Bakun
Hydroelectric Dam is the largest hydropower project in Malaysia that can produce up to
2400 MW of electricity (httpwwwsarawakenergycomrny)Itis the second highest
concrete faced rockfill dam in the world with an area of 695 square kilometers and a height
of 207 meters (httpwwwsarawakenergycomrny) Research on the characteristics of
physico-chemical water quality at Bakun Dam has been conducted by Nyanti (2012)
However it was conducted during the filling phase of the hydroelectric dam which is
fifteen months after impoundment has started Since then there has been no publishing
literature on the characteristics of the water quality
1
Hence the goal of this study is to obtain detailed information on the physicoshy
chemical water properties of the Bakun Hydroelectric Dam 3 years and 7 months after it
has reached its full supply level Therefore the objectives of this study were
(i) To determine the water quality at six depths at three stations in the
reservOIr
(ii) Compare the characteristics of the water quality among the depths and
stations and
(iii) Determine the changes in water quality characteristics 5 years 6 months
after the dam was impounded
2
jl - - I
20 Literature Review
21 Reservoir
According to Pawar amp Shembekar (2012) water is important and it is the most
abundant resource in the world which man has used for decades Water covers about 70
of the earths surface but only 27 of the total amount is freshwater of which 1 is iceshy
free water in the rivers lakes and atmosphere as biological water It is believed that only
0001 92 of the total water on earth is available for human use (Pawar amp Shembekar
2012) Hence reservoirs are created in order to provide domestic water supply generation
of electricity and aquaculture In Malaysia 63 large reservoirs with a total storage of 25
billion m3 have been constructed (Makhlough 2008)
Water quality in reservoirs is greatly affected by the composition of plant materials
that were submerged during the inundation process In a study done by Ling (2012) water
in the Batang Ai reservoir contains high sulfide concentrations especially at inundated
areas Besides that Nyanti (2012) also reported that the anoxic condition and the acidic
condition in Bakun Dam is due to the decomposition of submerged carbonaceous
materials
Additionally human activities in and around reservoirs and the physical and
chemical properties of water will be affected (Mustapha 2008) Precipitation evaporation
and ground movement can also affect water quality In Batang Ai reservoir the dissolved
oxygen was reported to be lower due to nearby cage aquaculture as it is consumed by
microorganisms in the decomposition of organic matter (Ling 2012)
22 Water quality
Water quality in a reservoir is the physical and chemical limnology of a reservoir
(Sidnei 1992) and includes all physical chemical and biological aspects of water that
3
influence the beneficial usage of water (Mustapha 2008) In reservoirs water quality
deterioration usually comes from excessive nutrient inputs eutrophication acidification
heavy metal contamination organic pollution and obnoxious fishing practices (Mustapha
2008)
Therefore water quality is an important indicator of the ecological status of a
reservoir It is reported that the significant lower dissolved oxygen is recorded due to
higher turbidity and increased suspended solids which affect the dissolution of oxygen
which is brought in by the flood that occurred in Oyun Reservoir (Mustapha 2008)
Additionally in a study done at Bakun Dam turbidity is affected by the suspended solids
from eroded soils from the logging activities in the watershed upstream from the north of
the reservoir (Nyanti 2012)
221 Temperature
Temperature is very important to a reservoir as it affects chemical and biological
activities of aquatic organisms (Sangpal 2011) In a reservoir when the upper layer and
the lower layer have great variation in temperature thermocline will occur Thermal
stratification in deep reservoir is an important natural process which gives significant
effects on water quality The production of ammonia sulphide and algal nutrients are
dependent on the changes in water temperature which subsequently affects the water
quality (Baharim 2011) Besides that vertical distribution and change in water
temperature can affect productivity of the natural organisms in the reservoirs However
the effect varies from reservoir to reservoir According to Li amp Xu (1995) thermocline is
common in reservoirs and usually occurs at the depth of 8m to 23m In a study done by
Nyanti (2012) water temperature in Bakun reservoir was reported to undergo thermocline
as depth increased from subsurface to 18m
4
l I
Pusat Khidmat Maldumat Akadfmil UN nsmMALAYSIA SARAWAI~
222 Dissolved Oxygen (DO)
DO is a very essential environmental factor that affects the entire production of a
reservoir and it is also an important indicator of water quality health of reservoir and also
ecological status as it is used for respiration and in biological and chemical reactions
(Mustapha 2008)
DO fluctuate from reservOIr to reservOIr and it is usually affected by
photosynthesis respiration and diel fluctuation In a study done by Ling (2012) it was
reported that the DO is higher at 05m depth at a11 stations in Batang Ai reservoir ranging
from 47 to 87 mgL due to the high phytoplankton photosynthesis rate An example of
diel fluctuation is shown in Kontagora reservoir where the DO is higher during the dry
season than the rainy season (Ibrahim 2009) This shows that the fluctuation also depends
on temperature depth wind and amount of biological activities such as decomposition In
Bakon Dam DO is high at the subsurface but dropped drastically until anoxic level at
depth 2 - 4m 2 years after impoundment and this is mainly due to the decomposition of
organic matter (Nyanti 2012)
223 pH
pH that is suitable for optimal production for inland waters should be about 65 to
85 (Ibrahim 2009) However changes in pH can affect the transfer of nutrients and affect
the condition ofwater quality (Li amp Xu 1995)
Fluctuations in pH can be caused by the photosynthesis process of phytoplanktons
as was reported in Batang Ai reservoir where all pH value was above 7 (Ling 2012)
Carbon dioxide produced by photosynthesis process will alter the pH of water as carbonic
acid will be formed when carbon dioxide reacts with water (Sangpal 2011)
5
Acidic effects in reservoirs can be caused by the transfer of cooler water from other
tributaries where the water is denser and lower in pH Nyanti (2012) reported the pH value
at Bakundam were all acidic ranging from 517-592 and the overall trend of pH in Bakun
dam decreases from upstream towards the dam (Nyanti et aI 2012)
224 Nutrients
Reservoirs are often have higher chances of getting higher element loading
compared to natural lakes as they have greater catchment area and high inflow rates
(Pawar amp Shembekar 2012) The concentration of nutrients varies from reservoir to
reservoir due to the differences in soil and vegetation in the catchment area (Li amp Xu
1995) Nutrients such as nitrates phosphates silicates and iron are important nutrients
required for aquatic growth but may also cause eutrophication and water quality problems
(Li amp Xu 1995) Eutrophication can occur easily in reservoir due to high input of nutrients
into the water and water quality of reservoir will be affected giving rise to unpleasant taste
and odour and affects the dissolution of other gases especially dissolved oxygen
(Mustapha 2008) According to Nyanti (2012) strong rotten egg smell discovered in
Bakun dam indicates high volume of hydrogen sulfide This observation is also supported
by Lourantou (2007) where an irritating odour smell occurs at a reservoir in Belgium
Nutrients input can also be affected by weather and season where nitrate was recorded at
higher values in Ujjani reservoir during post-monsoon season This may be caused by the
oxidation of nitrifying bacteria and biological nitrification Sulphate concentrations in the
dam were very high in both pre and post-monsoon which were probably caused by the
mineral rocks anthropogenically added and also by rain (Sangpal 2011) The phosphate
levels were found to be lower during the pre-monsoon and higher during the postshy
6
monsoon Phosphate leads to eutrophication that can cause unpleasant taste and odour to
the water (Sangpal 2011)
23 Impacts of hydroelectric dams on water quality
Hydroelectric dam has a direct impact to the water quality as it uses the flow rate of
a water course to produce electricity The building of hydroelectric dams has direct impact
towards the chemical thermal and physical parameters of the water body (Bunea 2012)
According to a study done by Bunea (2012) hydroelectric dams have relatively low DO
concentration mostly lower than 50 mglL because of the organic sediments that are left at
the bottom of the reservoir bottom during the initial filing Organic substances left at the
bottom of the reservoir bottom floor will absorb oxygen from the water in order to
decompose producing hydrogen sulphide carbon dioxide and methane (Bunea 2012)
Due to damming for hydroelectric generation water in a reservoir will undergo
stagnation which will lead to thermal stratification (Bunea 2012) According to a study
done by Elci (2008) thermal stratification of the reservoir involves the higher temperature
at the surface and lower temperatures at the bottom which suggests that thermal energy is
very slowly transferred to the bottom layers of the water body Thermal stratification act as
a barrier to re train mixing of the water column This causes an uneven concentration of
nutrients lack of light for photosynthesis at the hypolimnion and the water column may
become anoxic (Elci 2008)
Hydroelectric dams also greatly reduces the water self-purification capacity
According to Wei et al (2009) water self-purification mechanisms are affected by the
physical chemical and biotic processes in a reservoir However dam construction affects
all of the processes as the flow regime water quality and biotic community in the river In
other words dams slow down the river flow capacity block the river continuum and raise
7
water temperature which decreases the water self-purification capacity (Wei et aI 2009)
In a study done in China by Wei et al (2009) it is recorded that the Manwan-Dachaosan
dam has higher ammonia-nitrogen concentration due to the decreased water selfshy
purification capacity as compared to the pre-dam period This suggests that damming has
severely decreased the water self-purification capacity as it blocked the river continuum
8
30 Materials and Methods
31 Study Site
Bakun Hydroelectric Reservoir is a man-made reservoir which is located 60 km
west of Belaga Sarawak Malaysia (Figure 1) The dam was formed after the
impoundment of Balui River The reservoir has a catchment area of 14750 km2 and a total
capacity 43800000 m3 with a surface area of 695 km2 The dam is the second tallest
concrete-faced rockfill dam in the world
Three sampling stations namely stations 1 2 and 3 was selected in the reservoir
Station 1 is at the inundated estuary of the Linau River Station 2 is at the inundated Balui
River and Station 3 is located in the inundated Balui River as well but nearer to the dam
At each station sampling was conducted at 6 levels namely the subsurface 10m 20m
30m 4Om and 50m depths The coordinates of Bakun dam is at longitude 02deg45 23N and
latitude 114deg0347E The coordinates of every sampling station were recorded by the
Global Positioning System (GARMIN GPSMAP 62S) (Table 1) Sampling was carried
out twice the first sampling was from 21 SI August to 27th August 2015 and the second
sampling was 5th November to 11 th November 2015
9
i
EAST MALAYSIA
o
I
-I River I
-I Flooded Area
Station
0 Dam
kill I
Figure 1 Location of the three sampling stations at Bakun Reservoir
Table 1 Coordinates and locations of sampling stations
Station Coordinates Location
N 02deg 39 322 E 114deg 03 295 Estuary of Linau River
2 N 02deg 43 344 E 114deg 01 442 Balui River
3 N 02deg 43 4135 E 114deg 03 340 Further downstream of Balui River
10
32 Water samples
The water samples were taken using Van Dorn water sampler at all three stations
and were taken at 6 different depths which are the subsurface (02m) 10m 20m 30m 40m
and 5Om At each station three replicates of water samples were taken back for laboratory
analysis Water samples were kept in 2 L polyethylene water bottles that has been acid
washed and were stored in cooler box filled with ice All samples were taken to the
laboratory for further analysis
33 Water quality parameters measured in-situ
Temperature dissolved oxygen (DO) pH electrical conductivity total dissolved
solids (TDS) and turbidity were taken using YSI Multiparameter Water Quality 6920 V2
The depths of each station were measured using depth finder Water transparency was also
measured using secchi disc at each station
34 Water quality parameters analysed ex-situ
341 Biochemical oxygen demand in five days (BODs)
BODs were determined by filling water samples into 300 ml BOD bottles DO
readings of the water samples were measured from the bottles All BOD bottles were
wrapped with aluminum foil to prevent light penetration and were kept in a cooler box for
5 days The initial DO value was recorded as DJ and on the 5th day the DO reading was
recorded as Ds The formula that was used for measuring BODs follows the protocol
outlined by APHA (1998)
11
BOD5 (mglL) = DJ - D5
Where DJ = Initial DO of sample immediately after preparation (mglL)
D5 = DO value after 5 days incubation at 25degC (mglL)
342 Total suspended solids (TSS)
Total suspended solids were analyzed using standard method APHA (1998) For
TSS analysis there was pre-fieldtrip sampling method and post-fieldtrip method For preshy
fieldtrip method glass fibre filter paper (GFIC 47 nun diameter 045 Ilm membrane) were
soaked in distilled water Each filter paper is placed on a piece of aluminum foil and was
dried in the oven at 103degC - 105degC overnight Filter paper then was allowed to cool for 10
minutes before weighing it using an analytical balance (ACCULAB ALC - 210) The
initial weight was recorded For post-fieldtrip method the glass fibre paper was placed on
the inter-plate of the filter funnel using a pair of forceps A known volume of water
samples was filtered using a vacuum pump After that filter paper was removed from the
filtration funnel and was placed back into the aluminum foil Filter paper was dried in the
oven at 103degC - 105degC overnight (APHA 1998) Filter paper was then taken out of the
oven and allowed to cool until room temperature before weighing The final reading of the
filtered glass fibre paper was recorded and TSS was calculated using the formula
w -wTSS (mglL) = J I
V
Where W = Initial weight of filter paper
WJ = Final weight of filter paper
V = Volume of water samples filtered (L)
12
4 Chlorophyll-a
The concentration of chlorophyll-a In the water samples were analyzed using
staDdard method APHA (1998) For chlorophyll-a analysis water samples were filtered
using vacuum pump Filter paper containing chlorophyll-a was taken from the vacuum
pump for analysis The samples were grinded by using a grinder and 5 - 6 mL of 90
acetone was added into the mortar Samples were grinded for about 5 minutes and all
materials in the mortar were placed into a capped test tube Ninety percent acetone was
added into the test tube to make up the volume to 10mL Test tube was folded with
aluminum foil and was placed in the refrigerator for 4 - 18 hours to facilitate complete
extraction of the pigments The liquid extracted was transferred into the centrifuge tube
The samples were placed into a centrifuge for about 10 minutes under 3000 rpm Optical
density was determined using spectrophotometer at wavelength of 750 nm 664 run 647
am and 630 nm Each extinctions for small turbidity blank was corrected by subtracting
750 nm from 664 nm and 630 run absorptions
The concentration of chlorophyll-a in the extract of the pigment after correction was
calculated using
Where E = the absorption in the respective wavelength
After determining the concentration of the chlorophyll-a in the extract the amount of
cblorophyll-a in the pigment per unit volume of water filtered was calculated as follows
13
Ca(v)Chlorophyll-a (Jg IL) = - shyv
Where Co = Chlorophyll-a pigment concentration in JgmL
v = Volume ofacetone in mL
v = Volume of samples in L
344 Ammonia-nitrogen (NH3-N)
For ammonia-nitrogen (NH3-N) the concentration was determined using standard
method 8038 Nessler Method (HACH 2000) A 25 mL prepared sample and 25 mL of
deionized water were filled into a separate 25 mL mixing graduated cylinder Three drops
of Mineral Stabilizer were added to both of the cylinders The cylinders were inverted
several times to mix the content After that 1 mL of Nessler reagent was pipetted into both
of the cylinders and the cylinders were inverted several times to mix the content A one-
minute reaction was started Both the solutions were poured into a square sample cell A
yellow colour formation will indicate the presence of ammonia When the timer expired
the blank was inserted into the square sample cell with the fill line facing the right The
reading at 425 run was zeroed The prepared sample was inserted into the cell holder of
Spectrophotometer DR 2800 (HACH 2000) with the fill line facing right and the reading
displayed was recorded
345 Nitrate (NO)-)
For nitrate analysis the concentration was determined using standard method 8192
Cadmium Reduction Method (HACH 2000) The sample was filled until the 15 mL mark
of a 25 mL graduated measuring cylinder The content of one Nitra Ver6 Nitrate Reagent
Pillow Powder was added into the cylinder and capped with a stopper The cylinder was
14
Water Quality at Bakun HEP Reservoir Belaga Sarawak
Abstract
Since the water supply at Bakun Hydroelectric Dam reached its full supply level only one previous study has been done during the filling phase of the dam which was 3 years and 10 months earlier than this study As water in the reservoir is very important for the aquatic organisms in the reservoir and downstream of the dam a study was conducted at 3 stations to determine the selected water quality parameters 5 years 6 months after impoundment started At each station water in triplicate samples were collected at 6 levels which is the subsurface at 10m 20m 30m 40m and 50m depth Results showed that thermocline occurred at 3m to 10m depth at all stations DO at the subsurface (499 - 610 mgL) dropped drastically to anoxic level starting from 2m to 10m depth at all stations Water conductivity and turbidity increases while pH decreased as depth increased The highest chlorophyll-a (1168 J-lgL) was recorded at 10m depth with positive correlation with turbidity Increasing levels of ammonia-nitrogen (00533 - 06400 mgL) total suspended solids (330 - 6306 mgL) and five-day biochemical oxygen demand (186 - 430 mgL) were observed while depth increases Nitrate (001 - 022 mgL) nitrite (00020 - 01170 mgL) silica (039 - 154 mgL) and orthophosphate (00900 - 17067 mgL) showed different variations with depth This present study showed that the water quality at Bakun Hydroelectric Dam was improving and still changing compared to the previous study during the filling phase and has not stabilize even after 5 years 6 months after impoundment started
Keywords hydroelectric dam turbidity water quality nutrients
Abstrak
Sejak bekalan air di Empangan Hidroelektrik Bakun mencapai tahap penuh hanya satu kajian telah dijalankan semasa fasa pengisian iaitu 3 tahun dan 10 bulan lebih awal daripada kajian ini Disebabkan air di dalam empangan adalah sangat penting untuk organisma akuatik di dalam empangan dan bawah empangan satu kajian telah dijalankan di 3 stesen untuk mengenalpasti parameter kualiti air 5 tahun selepas penakungan bermula Di setiap stesen air telah diambil sebanyak tiga kali daripada 6 tahap iaitu subpermukaan 10m 20m 30m 40m dan 50m Hasil kajian menunjuk perbentukan termoklin pada kedalaman dari 3m ke 10m di semua stesen DO di subpermukaan (499shy610 mglL) menurun dengan drastik kepada tahap anoksik bermula pada kedalaman 2m ke 10m di semua stesen Konduktiviti air dan kekeruhan meningkat dan pH menurun dengan kedalaman Klorofil-a paling tinggi (1168 pgIL) adalah pada kedalaman 10m dan berkorelasi positijdengan kekeruhan air Peningkatan tahap ammonia-nitrogen (00533 shy06400 mgIL) jumlah pepejal terampai (330 - 6306 mgIL) dan keperluan oksigen biokimia selepas lima hari (186 - 430 mglL) meningkat apabila kedalaman meningkat Nitrat (001 - 022 mgIL) nitrit (00020 - 01170 mgIL) silika (039 - 154 mglL) dan ortofosfat (00900 - 17067 mglL) menunjukkan variasi yang berbeza dengan kedalaman Kajian ini menunjukkan bahawa kualiti air di Empangan Hidroelektrik Bakun bertambah baik dan masih berubah berbanding dengan kajian semasa fasa pengisian dan belum lagi staNI selepas 5 tahun dan 6 bulan sejak penakungan bermula
Kata kunci empangan hidroelektrik kekeruhan air kualiti air nutrien
III
Pusat Khidmat Maklumal Akadtmi UNIVEftSm MALAYSIA SAKAWA
TABLE OF CONTENTS
Declaration of Authorship
Acknowledgement
Abstract
Abstrak
Table of Contents
List of Figures
List of Tables
List of Abbreviations
10 Introduction
20 Literature Review
21 Reservoir
22 Water Quality
221 Temperature
222 Dissolved Oxygen (DO)
223 pH
224 Nutrients
23 Impact of Hydroelectric Dams on Water Quality
30 Materials and Methods
31 Study Site
32 Water Samples
33 Water Quality Parameters Measured In-situ
34 Water Quality Parameters Analysed Ex-situ
341 Biological Oxygen Demand (BODs)
342 Total Suspended Solids (TSS)
343 Chlorophyll-a
344 Ammonia-Nitrogen (NH3-N)
345 Nitrate (N03-)
346 Nitrite (N02-)
347 Orthophosphate (P043-)
348 Silica (Si04)
35 Statistical Analyses
Page
I
II
III
III
IV
VI
VII
VIII
3
3
3
4
5
5
6
7
9
9
11
11
11
11
12
13
14
14
15
16
16
17
IV
18 40 Results
41 Water Quality Parameters Measured In-situ 18
411 Water Depth and Transparency 18
412 Temperature 18
413 Ph 23
414 Water Turbidity 26
415 Water Conductivity 28
416 Dissolved Oxygen (DO) 31
42 Water Quality Parameters Measured Ex-situ 35
421 Chlorophyll-a 35
422 Biochemical Oxygen Demand in Five Days (BOD5) 37
423 Nitrate (NOf) 39
424 Nitrite (N02-) 42
425 Ammonia-Nitrogen (NH3-N) 44
426 Silica (Si04) 46
427 Orthophosphate (P043-) 48
428 Total Suspended Solids (TSS) 50
50 Discussion 52
51 Water Parameters Measured In-situ 52
52 Water Parameters Measured Ex-situ 57
60 Summary 63
70 Conclusion 65
80 References 66
90 Appendices 71
v
I
Figure
Figure 1
Figure 2
Figure 3
Figure 4
Figure 5
Figure 6
Figure 7
Figure 8
Figure 9
Figure 10
Figure 11
Figure 12
Figure 13
Figure 14
Figure 15
Figure 16
Figure 17
Figure 18
Figure 19
Figure 20
Figure 21
Figure 22
Figure 23
Figure 24
Figure 25
Figure 26
Figure 27
Figure 28
Figure 29
Figure 30
Figure 31
-
LIST OF FIGURES
Title Page
The location of sampling stations at Bakun Dam Sarawak 10
19
Temperature values in November 2015
Temperature values in August 2015
21
Temperature profile in August 2015 22
Temperature profile in November 2015 23
PH values in August 2015 24
PH values in November 2015 25
Turbidity values in August 2015 27
Turbidity values in November 2015 28
Water conductivity values in August 2015 29
Water conductivity values in November 2015 30
Dissolved oxygen (DO) values in August 2015 32
Dissolved oxygen (DO) values in November 2015 33
Dissolved oxygen (DO) profile in August 2015 34
Dissolved oxygen (DO) profile in November 2015 34
Chlorophyll-a values in August 2015 36
Chlorophyll-a values in November 2015 37
BODs values in August 2015 38
BODs values in November 2015 39
Nitrate-N values in August 2015 41
Nitrate-N values in November 2015 41
Nitrite-N values in August 2015 43
Nitrite-N values in November 2015 43
Ammonia-N values in August 2015 45
Ammonia-N values in November 2015 45
Silica values in August 2015 47
Silica values in November 2015 47
Orthophosphate values in August 2015 49
Orthophosphate values in November 2015 49
TSS values in August 2015 51
TSS values in November 2015 51
VI
LIST OF TABLES
Table Title Page
Table 1 Coordinates and locations of sampling stations 10
Table 2 Water depth and transparency values in August 2015 18
Table 3 Classification of water quality parameters according to NWQS 64
VII
LIST OF ABBREVIATIONS
degC Degree Celsius
lm Micrometre
BOD Biological Oxygen Demand
DO Dissolved Oxygen
km2 Kilometre Square
3m Cubic Metre
mgL Milligram per litre
mL Millilitre
L Litre
nm Nanometre
mm Millimetre
pH Potential of Hydrogen
N Nitrogen
N02- Nitrite
N03- Nitrate
P04 3- Orthophosphate
Si04 Silica
NH3-N Ammonia-Nitrogen
TSS Total Suspended Solids
TDS Total Dissolved Solids
GPS Global Positioning System
VIII
10 Introduction
Hydroelectric dams have been constructed worldwide to provide an alternative
energy source as petroleum in the world is depleting and is not renewable Hence
impoundment started around the world to collect water bodies to act as a reservoir
Reservoirs formed by impoundment they will undergo great changes in water
quality (Chapman 1996) This was observed in tropical reservoirs such as Feitsui
Reservoir in Taiwan (Chang and Wen 1997) and Lake Brokopondo in Surinam (Van der
Heide 1978) and also temperate reservoirs such as Butgenbuch Reservoir in Belgium
(Lourantou et aI 2007) and Bureye Reservoir in Russia (Shesterkin 2008) This happens
because of the impact of inundated soil and vegetation including the standing forest on the
water quality such as pH level and dissolved oxygen concentration (Van der Heide 1978
Shesterkin 2008) which is essential for aquatic life
In Malaysia hydroelectric dams have been constructed to meet the energy needs
and security Among the hydroelectric dams that have been built in Sarawak is the Bakun
Hydroelectric Dam Construction of the dam started in 2002 It is located about sixty
kilometers from the town of Belaga and is situated on the Balui River Bakun
Hydroelectric Dam is the largest hydropower project in Malaysia that can produce up to
2400 MW of electricity (httpwwwsarawakenergycomrny)Itis the second highest
concrete faced rockfill dam in the world with an area of 695 square kilometers and a height
of 207 meters (httpwwwsarawakenergycomrny) Research on the characteristics of
physico-chemical water quality at Bakun Dam has been conducted by Nyanti (2012)
However it was conducted during the filling phase of the hydroelectric dam which is
fifteen months after impoundment has started Since then there has been no publishing
literature on the characteristics of the water quality
1
Hence the goal of this study is to obtain detailed information on the physicoshy
chemical water properties of the Bakun Hydroelectric Dam 3 years and 7 months after it
has reached its full supply level Therefore the objectives of this study were
(i) To determine the water quality at six depths at three stations in the
reservOIr
(ii) Compare the characteristics of the water quality among the depths and
stations and
(iii) Determine the changes in water quality characteristics 5 years 6 months
after the dam was impounded
2
jl - - I
20 Literature Review
21 Reservoir
According to Pawar amp Shembekar (2012) water is important and it is the most
abundant resource in the world which man has used for decades Water covers about 70
of the earths surface but only 27 of the total amount is freshwater of which 1 is iceshy
free water in the rivers lakes and atmosphere as biological water It is believed that only
0001 92 of the total water on earth is available for human use (Pawar amp Shembekar
2012) Hence reservoirs are created in order to provide domestic water supply generation
of electricity and aquaculture In Malaysia 63 large reservoirs with a total storage of 25
billion m3 have been constructed (Makhlough 2008)
Water quality in reservoirs is greatly affected by the composition of plant materials
that were submerged during the inundation process In a study done by Ling (2012) water
in the Batang Ai reservoir contains high sulfide concentrations especially at inundated
areas Besides that Nyanti (2012) also reported that the anoxic condition and the acidic
condition in Bakun Dam is due to the decomposition of submerged carbonaceous
materials
Additionally human activities in and around reservoirs and the physical and
chemical properties of water will be affected (Mustapha 2008) Precipitation evaporation
and ground movement can also affect water quality In Batang Ai reservoir the dissolved
oxygen was reported to be lower due to nearby cage aquaculture as it is consumed by
microorganisms in the decomposition of organic matter (Ling 2012)
22 Water quality
Water quality in a reservoir is the physical and chemical limnology of a reservoir
(Sidnei 1992) and includes all physical chemical and biological aspects of water that
3
influence the beneficial usage of water (Mustapha 2008) In reservoirs water quality
deterioration usually comes from excessive nutrient inputs eutrophication acidification
heavy metal contamination organic pollution and obnoxious fishing practices (Mustapha
2008)
Therefore water quality is an important indicator of the ecological status of a
reservoir It is reported that the significant lower dissolved oxygen is recorded due to
higher turbidity and increased suspended solids which affect the dissolution of oxygen
which is brought in by the flood that occurred in Oyun Reservoir (Mustapha 2008)
Additionally in a study done at Bakun Dam turbidity is affected by the suspended solids
from eroded soils from the logging activities in the watershed upstream from the north of
the reservoir (Nyanti 2012)
221 Temperature
Temperature is very important to a reservoir as it affects chemical and biological
activities of aquatic organisms (Sangpal 2011) In a reservoir when the upper layer and
the lower layer have great variation in temperature thermocline will occur Thermal
stratification in deep reservoir is an important natural process which gives significant
effects on water quality The production of ammonia sulphide and algal nutrients are
dependent on the changes in water temperature which subsequently affects the water
quality (Baharim 2011) Besides that vertical distribution and change in water
temperature can affect productivity of the natural organisms in the reservoirs However
the effect varies from reservoir to reservoir According to Li amp Xu (1995) thermocline is
common in reservoirs and usually occurs at the depth of 8m to 23m In a study done by
Nyanti (2012) water temperature in Bakun reservoir was reported to undergo thermocline
as depth increased from subsurface to 18m
4
l I
Pusat Khidmat Maldumat Akadfmil UN nsmMALAYSIA SARAWAI~
222 Dissolved Oxygen (DO)
DO is a very essential environmental factor that affects the entire production of a
reservoir and it is also an important indicator of water quality health of reservoir and also
ecological status as it is used for respiration and in biological and chemical reactions
(Mustapha 2008)
DO fluctuate from reservOIr to reservOIr and it is usually affected by
photosynthesis respiration and diel fluctuation In a study done by Ling (2012) it was
reported that the DO is higher at 05m depth at a11 stations in Batang Ai reservoir ranging
from 47 to 87 mgL due to the high phytoplankton photosynthesis rate An example of
diel fluctuation is shown in Kontagora reservoir where the DO is higher during the dry
season than the rainy season (Ibrahim 2009) This shows that the fluctuation also depends
on temperature depth wind and amount of biological activities such as decomposition In
Bakon Dam DO is high at the subsurface but dropped drastically until anoxic level at
depth 2 - 4m 2 years after impoundment and this is mainly due to the decomposition of
organic matter (Nyanti 2012)
223 pH
pH that is suitable for optimal production for inland waters should be about 65 to
85 (Ibrahim 2009) However changes in pH can affect the transfer of nutrients and affect
the condition ofwater quality (Li amp Xu 1995)
Fluctuations in pH can be caused by the photosynthesis process of phytoplanktons
as was reported in Batang Ai reservoir where all pH value was above 7 (Ling 2012)
Carbon dioxide produced by photosynthesis process will alter the pH of water as carbonic
acid will be formed when carbon dioxide reacts with water (Sangpal 2011)
5
Acidic effects in reservoirs can be caused by the transfer of cooler water from other
tributaries where the water is denser and lower in pH Nyanti (2012) reported the pH value
at Bakundam were all acidic ranging from 517-592 and the overall trend of pH in Bakun
dam decreases from upstream towards the dam (Nyanti et aI 2012)
224 Nutrients
Reservoirs are often have higher chances of getting higher element loading
compared to natural lakes as they have greater catchment area and high inflow rates
(Pawar amp Shembekar 2012) The concentration of nutrients varies from reservoir to
reservoir due to the differences in soil and vegetation in the catchment area (Li amp Xu
1995) Nutrients such as nitrates phosphates silicates and iron are important nutrients
required for aquatic growth but may also cause eutrophication and water quality problems
(Li amp Xu 1995) Eutrophication can occur easily in reservoir due to high input of nutrients
into the water and water quality of reservoir will be affected giving rise to unpleasant taste
and odour and affects the dissolution of other gases especially dissolved oxygen
(Mustapha 2008) According to Nyanti (2012) strong rotten egg smell discovered in
Bakun dam indicates high volume of hydrogen sulfide This observation is also supported
by Lourantou (2007) where an irritating odour smell occurs at a reservoir in Belgium
Nutrients input can also be affected by weather and season where nitrate was recorded at
higher values in Ujjani reservoir during post-monsoon season This may be caused by the
oxidation of nitrifying bacteria and biological nitrification Sulphate concentrations in the
dam were very high in both pre and post-monsoon which were probably caused by the
mineral rocks anthropogenically added and also by rain (Sangpal 2011) The phosphate
levels were found to be lower during the pre-monsoon and higher during the postshy
6
monsoon Phosphate leads to eutrophication that can cause unpleasant taste and odour to
the water (Sangpal 2011)
23 Impacts of hydroelectric dams on water quality
Hydroelectric dam has a direct impact to the water quality as it uses the flow rate of
a water course to produce electricity The building of hydroelectric dams has direct impact
towards the chemical thermal and physical parameters of the water body (Bunea 2012)
According to a study done by Bunea (2012) hydroelectric dams have relatively low DO
concentration mostly lower than 50 mglL because of the organic sediments that are left at
the bottom of the reservoir bottom during the initial filing Organic substances left at the
bottom of the reservoir bottom floor will absorb oxygen from the water in order to
decompose producing hydrogen sulphide carbon dioxide and methane (Bunea 2012)
Due to damming for hydroelectric generation water in a reservoir will undergo
stagnation which will lead to thermal stratification (Bunea 2012) According to a study
done by Elci (2008) thermal stratification of the reservoir involves the higher temperature
at the surface and lower temperatures at the bottom which suggests that thermal energy is
very slowly transferred to the bottom layers of the water body Thermal stratification act as
a barrier to re train mixing of the water column This causes an uneven concentration of
nutrients lack of light for photosynthesis at the hypolimnion and the water column may
become anoxic (Elci 2008)
Hydroelectric dams also greatly reduces the water self-purification capacity
According to Wei et al (2009) water self-purification mechanisms are affected by the
physical chemical and biotic processes in a reservoir However dam construction affects
all of the processes as the flow regime water quality and biotic community in the river In
other words dams slow down the river flow capacity block the river continuum and raise
7
water temperature which decreases the water self-purification capacity (Wei et aI 2009)
In a study done in China by Wei et al (2009) it is recorded that the Manwan-Dachaosan
dam has higher ammonia-nitrogen concentration due to the decreased water selfshy
purification capacity as compared to the pre-dam period This suggests that damming has
severely decreased the water self-purification capacity as it blocked the river continuum
8
30 Materials and Methods
31 Study Site
Bakun Hydroelectric Reservoir is a man-made reservoir which is located 60 km
west of Belaga Sarawak Malaysia (Figure 1) The dam was formed after the
impoundment of Balui River The reservoir has a catchment area of 14750 km2 and a total
capacity 43800000 m3 with a surface area of 695 km2 The dam is the second tallest
concrete-faced rockfill dam in the world
Three sampling stations namely stations 1 2 and 3 was selected in the reservoir
Station 1 is at the inundated estuary of the Linau River Station 2 is at the inundated Balui
River and Station 3 is located in the inundated Balui River as well but nearer to the dam
At each station sampling was conducted at 6 levels namely the subsurface 10m 20m
30m 4Om and 50m depths The coordinates of Bakun dam is at longitude 02deg45 23N and
latitude 114deg0347E The coordinates of every sampling station were recorded by the
Global Positioning System (GARMIN GPSMAP 62S) (Table 1) Sampling was carried
out twice the first sampling was from 21 SI August to 27th August 2015 and the second
sampling was 5th November to 11 th November 2015
9
i
EAST MALAYSIA
o
I
-I River I
-I Flooded Area
Station
0 Dam
kill I
Figure 1 Location of the three sampling stations at Bakun Reservoir
Table 1 Coordinates and locations of sampling stations
Station Coordinates Location
N 02deg 39 322 E 114deg 03 295 Estuary of Linau River
2 N 02deg 43 344 E 114deg 01 442 Balui River
3 N 02deg 43 4135 E 114deg 03 340 Further downstream of Balui River
10
32 Water samples
The water samples were taken using Van Dorn water sampler at all three stations
and were taken at 6 different depths which are the subsurface (02m) 10m 20m 30m 40m
and 5Om At each station three replicates of water samples were taken back for laboratory
analysis Water samples were kept in 2 L polyethylene water bottles that has been acid
washed and were stored in cooler box filled with ice All samples were taken to the
laboratory for further analysis
33 Water quality parameters measured in-situ
Temperature dissolved oxygen (DO) pH electrical conductivity total dissolved
solids (TDS) and turbidity were taken using YSI Multiparameter Water Quality 6920 V2
The depths of each station were measured using depth finder Water transparency was also
measured using secchi disc at each station
34 Water quality parameters analysed ex-situ
341 Biochemical oxygen demand in five days (BODs)
BODs were determined by filling water samples into 300 ml BOD bottles DO
readings of the water samples were measured from the bottles All BOD bottles were
wrapped with aluminum foil to prevent light penetration and were kept in a cooler box for
5 days The initial DO value was recorded as DJ and on the 5th day the DO reading was
recorded as Ds The formula that was used for measuring BODs follows the protocol
outlined by APHA (1998)
11
BOD5 (mglL) = DJ - D5
Where DJ = Initial DO of sample immediately after preparation (mglL)
D5 = DO value after 5 days incubation at 25degC (mglL)
342 Total suspended solids (TSS)
Total suspended solids were analyzed using standard method APHA (1998) For
TSS analysis there was pre-fieldtrip sampling method and post-fieldtrip method For preshy
fieldtrip method glass fibre filter paper (GFIC 47 nun diameter 045 Ilm membrane) were
soaked in distilled water Each filter paper is placed on a piece of aluminum foil and was
dried in the oven at 103degC - 105degC overnight Filter paper then was allowed to cool for 10
minutes before weighing it using an analytical balance (ACCULAB ALC - 210) The
initial weight was recorded For post-fieldtrip method the glass fibre paper was placed on
the inter-plate of the filter funnel using a pair of forceps A known volume of water
samples was filtered using a vacuum pump After that filter paper was removed from the
filtration funnel and was placed back into the aluminum foil Filter paper was dried in the
oven at 103degC - 105degC overnight (APHA 1998) Filter paper was then taken out of the
oven and allowed to cool until room temperature before weighing The final reading of the
filtered glass fibre paper was recorded and TSS was calculated using the formula
w -wTSS (mglL) = J I
V
Where W = Initial weight of filter paper
WJ = Final weight of filter paper
V = Volume of water samples filtered (L)
12
4 Chlorophyll-a
The concentration of chlorophyll-a In the water samples were analyzed using
staDdard method APHA (1998) For chlorophyll-a analysis water samples were filtered
using vacuum pump Filter paper containing chlorophyll-a was taken from the vacuum
pump for analysis The samples were grinded by using a grinder and 5 - 6 mL of 90
acetone was added into the mortar Samples were grinded for about 5 minutes and all
materials in the mortar were placed into a capped test tube Ninety percent acetone was
added into the test tube to make up the volume to 10mL Test tube was folded with
aluminum foil and was placed in the refrigerator for 4 - 18 hours to facilitate complete
extraction of the pigments The liquid extracted was transferred into the centrifuge tube
The samples were placed into a centrifuge for about 10 minutes under 3000 rpm Optical
density was determined using spectrophotometer at wavelength of 750 nm 664 run 647
am and 630 nm Each extinctions for small turbidity blank was corrected by subtracting
750 nm from 664 nm and 630 run absorptions
The concentration of chlorophyll-a in the extract of the pigment after correction was
calculated using
Where E = the absorption in the respective wavelength
After determining the concentration of the chlorophyll-a in the extract the amount of
cblorophyll-a in the pigment per unit volume of water filtered was calculated as follows
13
Ca(v)Chlorophyll-a (Jg IL) = - shyv
Where Co = Chlorophyll-a pigment concentration in JgmL
v = Volume ofacetone in mL
v = Volume of samples in L
344 Ammonia-nitrogen (NH3-N)
For ammonia-nitrogen (NH3-N) the concentration was determined using standard
method 8038 Nessler Method (HACH 2000) A 25 mL prepared sample and 25 mL of
deionized water were filled into a separate 25 mL mixing graduated cylinder Three drops
of Mineral Stabilizer were added to both of the cylinders The cylinders were inverted
several times to mix the content After that 1 mL of Nessler reagent was pipetted into both
of the cylinders and the cylinders were inverted several times to mix the content A one-
minute reaction was started Both the solutions were poured into a square sample cell A
yellow colour formation will indicate the presence of ammonia When the timer expired
the blank was inserted into the square sample cell with the fill line facing the right The
reading at 425 run was zeroed The prepared sample was inserted into the cell holder of
Spectrophotometer DR 2800 (HACH 2000) with the fill line facing right and the reading
displayed was recorded
345 Nitrate (NO)-)
For nitrate analysis the concentration was determined using standard method 8192
Cadmium Reduction Method (HACH 2000) The sample was filled until the 15 mL mark
of a 25 mL graduated measuring cylinder The content of one Nitra Ver6 Nitrate Reagent
Pillow Powder was added into the cylinder and capped with a stopper The cylinder was
14
Pusat Khidmat Maklumal Akadtmi UNIVEftSm MALAYSIA SAKAWA
TABLE OF CONTENTS
Declaration of Authorship
Acknowledgement
Abstract
Abstrak
Table of Contents
List of Figures
List of Tables
List of Abbreviations
10 Introduction
20 Literature Review
21 Reservoir
22 Water Quality
221 Temperature
222 Dissolved Oxygen (DO)
223 pH
224 Nutrients
23 Impact of Hydroelectric Dams on Water Quality
30 Materials and Methods
31 Study Site
32 Water Samples
33 Water Quality Parameters Measured In-situ
34 Water Quality Parameters Analysed Ex-situ
341 Biological Oxygen Demand (BODs)
342 Total Suspended Solids (TSS)
343 Chlorophyll-a
344 Ammonia-Nitrogen (NH3-N)
345 Nitrate (N03-)
346 Nitrite (N02-)
347 Orthophosphate (P043-)
348 Silica (Si04)
35 Statistical Analyses
Page
I
II
III
III
IV
VI
VII
VIII
3
3
3
4
5
5
6
7
9
9
11
11
11
11
12
13
14
14
15
16
16
17
IV
18 40 Results
41 Water Quality Parameters Measured In-situ 18
411 Water Depth and Transparency 18
412 Temperature 18
413 Ph 23
414 Water Turbidity 26
415 Water Conductivity 28
416 Dissolved Oxygen (DO) 31
42 Water Quality Parameters Measured Ex-situ 35
421 Chlorophyll-a 35
422 Biochemical Oxygen Demand in Five Days (BOD5) 37
423 Nitrate (NOf) 39
424 Nitrite (N02-) 42
425 Ammonia-Nitrogen (NH3-N) 44
426 Silica (Si04) 46
427 Orthophosphate (P043-) 48
428 Total Suspended Solids (TSS) 50
50 Discussion 52
51 Water Parameters Measured In-situ 52
52 Water Parameters Measured Ex-situ 57
60 Summary 63
70 Conclusion 65
80 References 66
90 Appendices 71
v
I
Figure
Figure 1
Figure 2
Figure 3
Figure 4
Figure 5
Figure 6
Figure 7
Figure 8
Figure 9
Figure 10
Figure 11
Figure 12
Figure 13
Figure 14
Figure 15
Figure 16
Figure 17
Figure 18
Figure 19
Figure 20
Figure 21
Figure 22
Figure 23
Figure 24
Figure 25
Figure 26
Figure 27
Figure 28
Figure 29
Figure 30
Figure 31
-
LIST OF FIGURES
Title Page
The location of sampling stations at Bakun Dam Sarawak 10
19
Temperature values in November 2015
Temperature values in August 2015
21
Temperature profile in August 2015 22
Temperature profile in November 2015 23
PH values in August 2015 24
PH values in November 2015 25
Turbidity values in August 2015 27
Turbidity values in November 2015 28
Water conductivity values in August 2015 29
Water conductivity values in November 2015 30
Dissolved oxygen (DO) values in August 2015 32
Dissolved oxygen (DO) values in November 2015 33
Dissolved oxygen (DO) profile in August 2015 34
Dissolved oxygen (DO) profile in November 2015 34
Chlorophyll-a values in August 2015 36
Chlorophyll-a values in November 2015 37
BODs values in August 2015 38
BODs values in November 2015 39
Nitrate-N values in August 2015 41
Nitrate-N values in November 2015 41
Nitrite-N values in August 2015 43
Nitrite-N values in November 2015 43
Ammonia-N values in August 2015 45
Ammonia-N values in November 2015 45
Silica values in August 2015 47
Silica values in November 2015 47
Orthophosphate values in August 2015 49
Orthophosphate values in November 2015 49
TSS values in August 2015 51
TSS values in November 2015 51
VI
LIST OF TABLES
Table Title Page
Table 1 Coordinates and locations of sampling stations 10
Table 2 Water depth and transparency values in August 2015 18
Table 3 Classification of water quality parameters according to NWQS 64
VII
LIST OF ABBREVIATIONS
degC Degree Celsius
lm Micrometre
BOD Biological Oxygen Demand
DO Dissolved Oxygen
km2 Kilometre Square
3m Cubic Metre
mgL Milligram per litre
mL Millilitre
L Litre
nm Nanometre
mm Millimetre
pH Potential of Hydrogen
N Nitrogen
N02- Nitrite
N03- Nitrate
P04 3- Orthophosphate
Si04 Silica
NH3-N Ammonia-Nitrogen
TSS Total Suspended Solids
TDS Total Dissolved Solids
GPS Global Positioning System
VIII
10 Introduction
Hydroelectric dams have been constructed worldwide to provide an alternative
energy source as petroleum in the world is depleting and is not renewable Hence
impoundment started around the world to collect water bodies to act as a reservoir
Reservoirs formed by impoundment they will undergo great changes in water
quality (Chapman 1996) This was observed in tropical reservoirs such as Feitsui
Reservoir in Taiwan (Chang and Wen 1997) and Lake Brokopondo in Surinam (Van der
Heide 1978) and also temperate reservoirs such as Butgenbuch Reservoir in Belgium
(Lourantou et aI 2007) and Bureye Reservoir in Russia (Shesterkin 2008) This happens
because of the impact of inundated soil and vegetation including the standing forest on the
water quality such as pH level and dissolved oxygen concentration (Van der Heide 1978
Shesterkin 2008) which is essential for aquatic life
In Malaysia hydroelectric dams have been constructed to meet the energy needs
and security Among the hydroelectric dams that have been built in Sarawak is the Bakun
Hydroelectric Dam Construction of the dam started in 2002 It is located about sixty
kilometers from the town of Belaga and is situated on the Balui River Bakun
Hydroelectric Dam is the largest hydropower project in Malaysia that can produce up to
2400 MW of electricity (httpwwwsarawakenergycomrny)Itis the second highest
concrete faced rockfill dam in the world with an area of 695 square kilometers and a height
of 207 meters (httpwwwsarawakenergycomrny) Research on the characteristics of
physico-chemical water quality at Bakun Dam has been conducted by Nyanti (2012)
However it was conducted during the filling phase of the hydroelectric dam which is
fifteen months after impoundment has started Since then there has been no publishing
literature on the characteristics of the water quality
1
Hence the goal of this study is to obtain detailed information on the physicoshy
chemical water properties of the Bakun Hydroelectric Dam 3 years and 7 months after it
has reached its full supply level Therefore the objectives of this study were
(i) To determine the water quality at six depths at three stations in the
reservOIr
(ii) Compare the characteristics of the water quality among the depths and
stations and
(iii) Determine the changes in water quality characteristics 5 years 6 months
after the dam was impounded
2
jl - - I
20 Literature Review
21 Reservoir
According to Pawar amp Shembekar (2012) water is important and it is the most
abundant resource in the world which man has used for decades Water covers about 70
of the earths surface but only 27 of the total amount is freshwater of which 1 is iceshy
free water in the rivers lakes and atmosphere as biological water It is believed that only
0001 92 of the total water on earth is available for human use (Pawar amp Shembekar
2012) Hence reservoirs are created in order to provide domestic water supply generation
of electricity and aquaculture In Malaysia 63 large reservoirs with a total storage of 25
billion m3 have been constructed (Makhlough 2008)
Water quality in reservoirs is greatly affected by the composition of plant materials
that were submerged during the inundation process In a study done by Ling (2012) water
in the Batang Ai reservoir contains high sulfide concentrations especially at inundated
areas Besides that Nyanti (2012) also reported that the anoxic condition and the acidic
condition in Bakun Dam is due to the decomposition of submerged carbonaceous
materials
Additionally human activities in and around reservoirs and the physical and
chemical properties of water will be affected (Mustapha 2008) Precipitation evaporation
and ground movement can also affect water quality In Batang Ai reservoir the dissolved
oxygen was reported to be lower due to nearby cage aquaculture as it is consumed by
microorganisms in the decomposition of organic matter (Ling 2012)
22 Water quality
Water quality in a reservoir is the physical and chemical limnology of a reservoir
(Sidnei 1992) and includes all physical chemical and biological aspects of water that
3
influence the beneficial usage of water (Mustapha 2008) In reservoirs water quality
deterioration usually comes from excessive nutrient inputs eutrophication acidification
heavy metal contamination organic pollution and obnoxious fishing practices (Mustapha
2008)
Therefore water quality is an important indicator of the ecological status of a
reservoir It is reported that the significant lower dissolved oxygen is recorded due to
higher turbidity and increased suspended solids which affect the dissolution of oxygen
which is brought in by the flood that occurred in Oyun Reservoir (Mustapha 2008)
Additionally in a study done at Bakun Dam turbidity is affected by the suspended solids
from eroded soils from the logging activities in the watershed upstream from the north of
the reservoir (Nyanti 2012)
221 Temperature
Temperature is very important to a reservoir as it affects chemical and biological
activities of aquatic organisms (Sangpal 2011) In a reservoir when the upper layer and
the lower layer have great variation in temperature thermocline will occur Thermal
stratification in deep reservoir is an important natural process which gives significant
effects on water quality The production of ammonia sulphide and algal nutrients are
dependent on the changes in water temperature which subsequently affects the water
quality (Baharim 2011) Besides that vertical distribution and change in water
temperature can affect productivity of the natural organisms in the reservoirs However
the effect varies from reservoir to reservoir According to Li amp Xu (1995) thermocline is
common in reservoirs and usually occurs at the depth of 8m to 23m In a study done by
Nyanti (2012) water temperature in Bakun reservoir was reported to undergo thermocline
as depth increased from subsurface to 18m
4
l I
Pusat Khidmat Maldumat Akadfmil UN nsmMALAYSIA SARAWAI~
222 Dissolved Oxygen (DO)
DO is a very essential environmental factor that affects the entire production of a
reservoir and it is also an important indicator of water quality health of reservoir and also
ecological status as it is used for respiration and in biological and chemical reactions
(Mustapha 2008)
DO fluctuate from reservOIr to reservOIr and it is usually affected by
photosynthesis respiration and diel fluctuation In a study done by Ling (2012) it was
reported that the DO is higher at 05m depth at a11 stations in Batang Ai reservoir ranging
from 47 to 87 mgL due to the high phytoplankton photosynthesis rate An example of
diel fluctuation is shown in Kontagora reservoir where the DO is higher during the dry
season than the rainy season (Ibrahim 2009) This shows that the fluctuation also depends
on temperature depth wind and amount of biological activities such as decomposition In
Bakon Dam DO is high at the subsurface but dropped drastically until anoxic level at
depth 2 - 4m 2 years after impoundment and this is mainly due to the decomposition of
organic matter (Nyanti 2012)
223 pH
pH that is suitable for optimal production for inland waters should be about 65 to
85 (Ibrahim 2009) However changes in pH can affect the transfer of nutrients and affect
the condition ofwater quality (Li amp Xu 1995)
Fluctuations in pH can be caused by the photosynthesis process of phytoplanktons
as was reported in Batang Ai reservoir where all pH value was above 7 (Ling 2012)
Carbon dioxide produced by photosynthesis process will alter the pH of water as carbonic
acid will be formed when carbon dioxide reacts with water (Sangpal 2011)
5
Acidic effects in reservoirs can be caused by the transfer of cooler water from other
tributaries where the water is denser and lower in pH Nyanti (2012) reported the pH value
at Bakundam were all acidic ranging from 517-592 and the overall trend of pH in Bakun
dam decreases from upstream towards the dam (Nyanti et aI 2012)
224 Nutrients
Reservoirs are often have higher chances of getting higher element loading
compared to natural lakes as they have greater catchment area and high inflow rates
(Pawar amp Shembekar 2012) The concentration of nutrients varies from reservoir to
reservoir due to the differences in soil and vegetation in the catchment area (Li amp Xu
1995) Nutrients such as nitrates phosphates silicates and iron are important nutrients
required for aquatic growth but may also cause eutrophication and water quality problems
(Li amp Xu 1995) Eutrophication can occur easily in reservoir due to high input of nutrients
into the water and water quality of reservoir will be affected giving rise to unpleasant taste
and odour and affects the dissolution of other gases especially dissolved oxygen
(Mustapha 2008) According to Nyanti (2012) strong rotten egg smell discovered in
Bakun dam indicates high volume of hydrogen sulfide This observation is also supported
by Lourantou (2007) where an irritating odour smell occurs at a reservoir in Belgium
Nutrients input can also be affected by weather and season where nitrate was recorded at
higher values in Ujjani reservoir during post-monsoon season This may be caused by the
oxidation of nitrifying bacteria and biological nitrification Sulphate concentrations in the
dam were very high in both pre and post-monsoon which were probably caused by the
mineral rocks anthropogenically added and also by rain (Sangpal 2011) The phosphate
levels were found to be lower during the pre-monsoon and higher during the postshy
6
monsoon Phosphate leads to eutrophication that can cause unpleasant taste and odour to
the water (Sangpal 2011)
23 Impacts of hydroelectric dams on water quality
Hydroelectric dam has a direct impact to the water quality as it uses the flow rate of
a water course to produce electricity The building of hydroelectric dams has direct impact
towards the chemical thermal and physical parameters of the water body (Bunea 2012)
According to a study done by Bunea (2012) hydroelectric dams have relatively low DO
concentration mostly lower than 50 mglL because of the organic sediments that are left at
the bottom of the reservoir bottom during the initial filing Organic substances left at the
bottom of the reservoir bottom floor will absorb oxygen from the water in order to
decompose producing hydrogen sulphide carbon dioxide and methane (Bunea 2012)
Due to damming for hydroelectric generation water in a reservoir will undergo
stagnation which will lead to thermal stratification (Bunea 2012) According to a study
done by Elci (2008) thermal stratification of the reservoir involves the higher temperature
at the surface and lower temperatures at the bottom which suggests that thermal energy is
very slowly transferred to the bottom layers of the water body Thermal stratification act as
a barrier to re train mixing of the water column This causes an uneven concentration of
nutrients lack of light for photosynthesis at the hypolimnion and the water column may
become anoxic (Elci 2008)
Hydroelectric dams also greatly reduces the water self-purification capacity
According to Wei et al (2009) water self-purification mechanisms are affected by the
physical chemical and biotic processes in a reservoir However dam construction affects
all of the processes as the flow regime water quality and biotic community in the river In
other words dams slow down the river flow capacity block the river continuum and raise
7
water temperature which decreases the water self-purification capacity (Wei et aI 2009)
In a study done in China by Wei et al (2009) it is recorded that the Manwan-Dachaosan
dam has higher ammonia-nitrogen concentration due to the decreased water selfshy
purification capacity as compared to the pre-dam period This suggests that damming has
severely decreased the water self-purification capacity as it blocked the river continuum
8
30 Materials and Methods
31 Study Site
Bakun Hydroelectric Reservoir is a man-made reservoir which is located 60 km
west of Belaga Sarawak Malaysia (Figure 1) The dam was formed after the
impoundment of Balui River The reservoir has a catchment area of 14750 km2 and a total
capacity 43800000 m3 with a surface area of 695 km2 The dam is the second tallest
concrete-faced rockfill dam in the world
Three sampling stations namely stations 1 2 and 3 was selected in the reservoir
Station 1 is at the inundated estuary of the Linau River Station 2 is at the inundated Balui
River and Station 3 is located in the inundated Balui River as well but nearer to the dam
At each station sampling was conducted at 6 levels namely the subsurface 10m 20m
30m 4Om and 50m depths The coordinates of Bakun dam is at longitude 02deg45 23N and
latitude 114deg0347E The coordinates of every sampling station were recorded by the
Global Positioning System (GARMIN GPSMAP 62S) (Table 1) Sampling was carried
out twice the first sampling was from 21 SI August to 27th August 2015 and the second
sampling was 5th November to 11 th November 2015
9
i
EAST MALAYSIA
o
I
-I River I
-I Flooded Area
Station
0 Dam
kill I
Figure 1 Location of the three sampling stations at Bakun Reservoir
Table 1 Coordinates and locations of sampling stations
Station Coordinates Location
N 02deg 39 322 E 114deg 03 295 Estuary of Linau River
2 N 02deg 43 344 E 114deg 01 442 Balui River
3 N 02deg 43 4135 E 114deg 03 340 Further downstream of Balui River
10
32 Water samples
The water samples were taken using Van Dorn water sampler at all three stations
and were taken at 6 different depths which are the subsurface (02m) 10m 20m 30m 40m
and 5Om At each station three replicates of water samples were taken back for laboratory
analysis Water samples were kept in 2 L polyethylene water bottles that has been acid
washed and were stored in cooler box filled with ice All samples were taken to the
laboratory for further analysis
33 Water quality parameters measured in-situ
Temperature dissolved oxygen (DO) pH electrical conductivity total dissolved
solids (TDS) and turbidity were taken using YSI Multiparameter Water Quality 6920 V2
The depths of each station were measured using depth finder Water transparency was also
measured using secchi disc at each station
34 Water quality parameters analysed ex-situ
341 Biochemical oxygen demand in five days (BODs)
BODs were determined by filling water samples into 300 ml BOD bottles DO
readings of the water samples were measured from the bottles All BOD bottles were
wrapped with aluminum foil to prevent light penetration and were kept in a cooler box for
5 days The initial DO value was recorded as DJ and on the 5th day the DO reading was
recorded as Ds The formula that was used for measuring BODs follows the protocol
outlined by APHA (1998)
11
BOD5 (mglL) = DJ - D5
Where DJ = Initial DO of sample immediately after preparation (mglL)
D5 = DO value after 5 days incubation at 25degC (mglL)
342 Total suspended solids (TSS)
Total suspended solids were analyzed using standard method APHA (1998) For
TSS analysis there was pre-fieldtrip sampling method and post-fieldtrip method For preshy
fieldtrip method glass fibre filter paper (GFIC 47 nun diameter 045 Ilm membrane) were
soaked in distilled water Each filter paper is placed on a piece of aluminum foil and was
dried in the oven at 103degC - 105degC overnight Filter paper then was allowed to cool for 10
minutes before weighing it using an analytical balance (ACCULAB ALC - 210) The
initial weight was recorded For post-fieldtrip method the glass fibre paper was placed on
the inter-plate of the filter funnel using a pair of forceps A known volume of water
samples was filtered using a vacuum pump After that filter paper was removed from the
filtration funnel and was placed back into the aluminum foil Filter paper was dried in the
oven at 103degC - 105degC overnight (APHA 1998) Filter paper was then taken out of the
oven and allowed to cool until room temperature before weighing The final reading of the
filtered glass fibre paper was recorded and TSS was calculated using the formula
w -wTSS (mglL) = J I
V
Where W = Initial weight of filter paper
WJ = Final weight of filter paper
V = Volume of water samples filtered (L)
12
4 Chlorophyll-a
The concentration of chlorophyll-a In the water samples were analyzed using
staDdard method APHA (1998) For chlorophyll-a analysis water samples were filtered
using vacuum pump Filter paper containing chlorophyll-a was taken from the vacuum
pump for analysis The samples were grinded by using a grinder and 5 - 6 mL of 90
acetone was added into the mortar Samples were grinded for about 5 minutes and all
materials in the mortar were placed into a capped test tube Ninety percent acetone was
added into the test tube to make up the volume to 10mL Test tube was folded with
aluminum foil and was placed in the refrigerator for 4 - 18 hours to facilitate complete
extraction of the pigments The liquid extracted was transferred into the centrifuge tube
The samples were placed into a centrifuge for about 10 minutes under 3000 rpm Optical
density was determined using spectrophotometer at wavelength of 750 nm 664 run 647
am and 630 nm Each extinctions for small turbidity blank was corrected by subtracting
750 nm from 664 nm and 630 run absorptions
The concentration of chlorophyll-a in the extract of the pigment after correction was
calculated using
Where E = the absorption in the respective wavelength
After determining the concentration of the chlorophyll-a in the extract the amount of
cblorophyll-a in the pigment per unit volume of water filtered was calculated as follows
13
Ca(v)Chlorophyll-a (Jg IL) = - shyv
Where Co = Chlorophyll-a pigment concentration in JgmL
v = Volume ofacetone in mL
v = Volume of samples in L
344 Ammonia-nitrogen (NH3-N)
For ammonia-nitrogen (NH3-N) the concentration was determined using standard
method 8038 Nessler Method (HACH 2000) A 25 mL prepared sample and 25 mL of
deionized water were filled into a separate 25 mL mixing graduated cylinder Three drops
of Mineral Stabilizer were added to both of the cylinders The cylinders were inverted
several times to mix the content After that 1 mL of Nessler reagent was pipetted into both
of the cylinders and the cylinders were inverted several times to mix the content A one-
minute reaction was started Both the solutions were poured into a square sample cell A
yellow colour formation will indicate the presence of ammonia When the timer expired
the blank was inserted into the square sample cell with the fill line facing the right The
reading at 425 run was zeroed The prepared sample was inserted into the cell holder of
Spectrophotometer DR 2800 (HACH 2000) with the fill line facing right and the reading
displayed was recorded
345 Nitrate (NO)-)
For nitrate analysis the concentration was determined using standard method 8192
Cadmium Reduction Method (HACH 2000) The sample was filled until the 15 mL mark
of a 25 mL graduated measuring cylinder The content of one Nitra Ver6 Nitrate Reagent
Pillow Powder was added into the cylinder and capped with a stopper The cylinder was
14
18 40 Results
41 Water Quality Parameters Measured In-situ 18
411 Water Depth and Transparency 18
412 Temperature 18
413 Ph 23
414 Water Turbidity 26
415 Water Conductivity 28
416 Dissolved Oxygen (DO) 31
42 Water Quality Parameters Measured Ex-situ 35
421 Chlorophyll-a 35
422 Biochemical Oxygen Demand in Five Days (BOD5) 37
423 Nitrate (NOf) 39
424 Nitrite (N02-) 42
425 Ammonia-Nitrogen (NH3-N) 44
426 Silica (Si04) 46
427 Orthophosphate (P043-) 48
428 Total Suspended Solids (TSS) 50
50 Discussion 52
51 Water Parameters Measured In-situ 52
52 Water Parameters Measured Ex-situ 57
60 Summary 63
70 Conclusion 65
80 References 66
90 Appendices 71
v
I
Figure
Figure 1
Figure 2
Figure 3
Figure 4
Figure 5
Figure 6
Figure 7
Figure 8
Figure 9
Figure 10
Figure 11
Figure 12
Figure 13
Figure 14
Figure 15
Figure 16
Figure 17
Figure 18
Figure 19
Figure 20
Figure 21
Figure 22
Figure 23
Figure 24
Figure 25
Figure 26
Figure 27
Figure 28
Figure 29
Figure 30
Figure 31
-
LIST OF FIGURES
Title Page
The location of sampling stations at Bakun Dam Sarawak 10
19
Temperature values in November 2015
Temperature values in August 2015
21
Temperature profile in August 2015 22
Temperature profile in November 2015 23
PH values in August 2015 24
PH values in November 2015 25
Turbidity values in August 2015 27
Turbidity values in November 2015 28
Water conductivity values in August 2015 29
Water conductivity values in November 2015 30
Dissolved oxygen (DO) values in August 2015 32
Dissolved oxygen (DO) values in November 2015 33
Dissolved oxygen (DO) profile in August 2015 34
Dissolved oxygen (DO) profile in November 2015 34
Chlorophyll-a values in August 2015 36
Chlorophyll-a values in November 2015 37
BODs values in August 2015 38
BODs values in November 2015 39
Nitrate-N values in August 2015 41
Nitrate-N values in November 2015 41
Nitrite-N values in August 2015 43
Nitrite-N values in November 2015 43
Ammonia-N values in August 2015 45
Ammonia-N values in November 2015 45
Silica values in August 2015 47
Silica values in November 2015 47
Orthophosphate values in August 2015 49
Orthophosphate values in November 2015 49
TSS values in August 2015 51
TSS values in November 2015 51
VI
LIST OF TABLES
Table Title Page
Table 1 Coordinates and locations of sampling stations 10
Table 2 Water depth and transparency values in August 2015 18
Table 3 Classification of water quality parameters according to NWQS 64
VII
LIST OF ABBREVIATIONS
degC Degree Celsius
lm Micrometre
BOD Biological Oxygen Demand
DO Dissolved Oxygen
km2 Kilometre Square
3m Cubic Metre
mgL Milligram per litre
mL Millilitre
L Litre
nm Nanometre
mm Millimetre
pH Potential of Hydrogen
N Nitrogen
N02- Nitrite
N03- Nitrate
P04 3- Orthophosphate
Si04 Silica
NH3-N Ammonia-Nitrogen
TSS Total Suspended Solids
TDS Total Dissolved Solids
GPS Global Positioning System
VIII
10 Introduction
Hydroelectric dams have been constructed worldwide to provide an alternative
energy source as petroleum in the world is depleting and is not renewable Hence
impoundment started around the world to collect water bodies to act as a reservoir
Reservoirs formed by impoundment they will undergo great changes in water
quality (Chapman 1996) This was observed in tropical reservoirs such as Feitsui
Reservoir in Taiwan (Chang and Wen 1997) and Lake Brokopondo in Surinam (Van der
Heide 1978) and also temperate reservoirs such as Butgenbuch Reservoir in Belgium
(Lourantou et aI 2007) and Bureye Reservoir in Russia (Shesterkin 2008) This happens
because of the impact of inundated soil and vegetation including the standing forest on the
water quality such as pH level and dissolved oxygen concentration (Van der Heide 1978
Shesterkin 2008) which is essential for aquatic life
In Malaysia hydroelectric dams have been constructed to meet the energy needs
and security Among the hydroelectric dams that have been built in Sarawak is the Bakun
Hydroelectric Dam Construction of the dam started in 2002 It is located about sixty
kilometers from the town of Belaga and is situated on the Balui River Bakun
Hydroelectric Dam is the largest hydropower project in Malaysia that can produce up to
2400 MW of electricity (httpwwwsarawakenergycomrny)Itis the second highest
concrete faced rockfill dam in the world with an area of 695 square kilometers and a height
of 207 meters (httpwwwsarawakenergycomrny) Research on the characteristics of
physico-chemical water quality at Bakun Dam has been conducted by Nyanti (2012)
However it was conducted during the filling phase of the hydroelectric dam which is
fifteen months after impoundment has started Since then there has been no publishing
literature on the characteristics of the water quality
1
Hence the goal of this study is to obtain detailed information on the physicoshy
chemical water properties of the Bakun Hydroelectric Dam 3 years and 7 months after it
has reached its full supply level Therefore the objectives of this study were
(i) To determine the water quality at six depths at three stations in the
reservOIr
(ii) Compare the characteristics of the water quality among the depths and
stations and
(iii) Determine the changes in water quality characteristics 5 years 6 months
after the dam was impounded
2
jl - - I
20 Literature Review
21 Reservoir
According to Pawar amp Shembekar (2012) water is important and it is the most
abundant resource in the world which man has used for decades Water covers about 70
of the earths surface but only 27 of the total amount is freshwater of which 1 is iceshy
free water in the rivers lakes and atmosphere as biological water It is believed that only
0001 92 of the total water on earth is available for human use (Pawar amp Shembekar
2012) Hence reservoirs are created in order to provide domestic water supply generation
of electricity and aquaculture In Malaysia 63 large reservoirs with a total storage of 25
billion m3 have been constructed (Makhlough 2008)
Water quality in reservoirs is greatly affected by the composition of plant materials
that were submerged during the inundation process In a study done by Ling (2012) water
in the Batang Ai reservoir contains high sulfide concentrations especially at inundated
areas Besides that Nyanti (2012) also reported that the anoxic condition and the acidic
condition in Bakun Dam is due to the decomposition of submerged carbonaceous
materials
Additionally human activities in and around reservoirs and the physical and
chemical properties of water will be affected (Mustapha 2008) Precipitation evaporation
and ground movement can also affect water quality In Batang Ai reservoir the dissolved
oxygen was reported to be lower due to nearby cage aquaculture as it is consumed by
microorganisms in the decomposition of organic matter (Ling 2012)
22 Water quality
Water quality in a reservoir is the physical and chemical limnology of a reservoir
(Sidnei 1992) and includes all physical chemical and biological aspects of water that
3
influence the beneficial usage of water (Mustapha 2008) In reservoirs water quality
deterioration usually comes from excessive nutrient inputs eutrophication acidification
heavy metal contamination organic pollution and obnoxious fishing practices (Mustapha
2008)
Therefore water quality is an important indicator of the ecological status of a
reservoir It is reported that the significant lower dissolved oxygen is recorded due to
higher turbidity and increased suspended solids which affect the dissolution of oxygen
which is brought in by the flood that occurred in Oyun Reservoir (Mustapha 2008)
Additionally in a study done at Bakun Dam turbidity is affected by the suspended solids
from eroded soils from the logging activities in the watershed upstream from the north of
the reservoir (Nyanti 2012)
221 Temperature
Temperature is very important to a reservoir as it affects chemical and biological
activities of aquatic organisms (Sangpal 2011) In a reservoir when the upper layer and
the lower layer have great variation in temperature thermocline will occur Thermal
stratification in deep reservoir is an important natural process which gives significant
effects on water quality The production of ammonia sulphide and algal nutrients are
dependent on the changes in water temperature which subsequently affects the water
quality (Baharim 2011) Besides that vertical distribution and change in water
temperature can affect productivity of the natural organisms in the reservoirs However
the effect varies from reservoir to reservoir According to Li amp Xu (1995) thermocline is
common in reservoirs and usually occurs at the depth of 8m to 23m In a study done by
Nyanti (2012) water temperature in Bakun reservoir was reported to undergo thermocline
as depth increased from subsurface to 18m
4
l I
Pusat Khidmat Maldumat Akadfmil UN nsmMALAYSIA SARAWAI~
222 Dissolved Oxygen (DO)
DO is a very essential environmental factor that affects the entire production of a
reservoir and it is also an important indicator of water quality health of reservoir and also
ecological status as it is used for respiration and in biological and chemical reactions
(Mustapha 2008)
DO fluctuate from reservOIr to reservOIr and it is usually affected by
photosynthesis respiration and diel fluctuation In a study done by Ling (2012) it was
reported that the DO is higher at 05m depth at a11 stations in Batang Ai reservoir ranging
from 47 to 87 mgL due to the high phytoplankton photosynthesis rate An example of
diel fluctuation is shown in Kontagora reservoir where the DO is higher during the dry
season than the rainy season (Ibrahim 2009) This shows that the fluctuation also depends
on temperature depth wind and amount of biological activities such as decomposition In
Bakon Dam DO is high at the subsurface but dropped drastically until anoxic level at
depth 2 - 4m 2 years after impoundment and this is mainly due to the decomposition of
organic matter (Nyanti 2012)
223 pH
pH that is suitable for optimal production for inland waters should be about 65 to
85 (Ibrahim 2009) However changes in pH can affect the transfer of nutrients and affect
the condition ofwater quality (Li amp Xu 1995)
Fluctuations in pH can be caused by the photosynthesis process of phytoplanktons
as was reported in Batang Ai reservoir where all pH value was above 7 (Ling 2012)
Carbon dioxide produced by photosynthesis process will alter the pH of water as carbonic
acid will be formed when carbon dioxide reacts with water (Sangpal 2011)
5
Acidic effects in reservoirs can be caused by the transfer of cooler water from other
tributaries where the water is denser and lower in pH Nyanti (2012) reported the pH value
at Bakundam were all acidic ranging from 517-592 and the overall trend of pH in Bakun
dam decreases from upstream towards the dam (Nyanti et aI 2012)
224 Nutrients
Reservoirs are often have higher chances of getting higher element loading
compared to natural lakes as they have greater catchment area and high inflow rates
(Pawar amp Shembekar 2012) The concentration of nutrients varies from reservoir to
reservoir due to the differences in soil and vegetation in the catchment area (Li amp Xu
1995) Nutrients such as nitrates phosphates silicates and iron are important nutrients
required for aquatic growth but may also cause eutrophication and water quality problems
(Li amp Xu 1995) Eutrophication can occur easily in reservoir due to high input of nutrients
into the water and water quality of reservoir will be affected giving rise to unpleasant taste
and odour and affects the dissolution of other gases especially dissolved oxygen
(Mustapha 2008) According to Nyanti (2012) strong rotten egg smell discovered in
Bakun dam indicates high volume of hydrogen sulfide This observation is also supported
by Lourantou (2007) where an irritating odour smell occurs at a reservoir in Belgium
Nutrients input can also be affected by weather and season where nitrate was recorded at
higher values in Ujjani reservoir during post-monsoon season This may be caused by the
oxidation of nitrifying bacteria and biological nitrification Sulphate concentrations in the
dam were very high in both pre and post-monsoon which were probably caused by the
mineral rocks anthropogenically added and also by rain (Sangpal 2011) The phosphate
levels were found to be lower during the pre-monsoon and higher during the postshy
6
monsoon Phosphate leads to eutrophication that can cause unpleasant taste and odour to
the water (Sangpal 2011)
23 Impacts of hydroelectric dams on water quality
Hydroelectric dam has a direct impact to the water quality as it uses the flow rate of
a water course to produce electricity The building of hydroelectric dams has direct impact
towards the chemical thermal and physical parameters of the water body (Bunea 2012)
According to a study done by Bunea (2012) hydroelectric dams have relatively low DO
concentration mostly lower than 50 mglL because of the organic sediments that are left at
the bottom of the reservoir bottom during the initial filing Organic substances left at the
bottom of the reservoir bottom floor will absorb oxygen from the water in order to
decompose producing hydrogen sulphide carbon dioxide and methane (Bunea 2012)
Due to damming for hydroelectric generation water in a reservoir will undergo
stagnation which will lead to thermal stratification (Bunea 2012) According to a study
done by Elci (2008) thermal stratification of the reservoir involves the higher temperature
at the surface and lower temperatures at the bottom which suggests that thermal energy is
very slowly transferred to the bottom layers of the water body Thermal stratification act as
a barrier to re train mixing of the water column This causes an uneven concentration of
nutrients lack of light for photosynthesis at the hypolimnion and the water column may
become anoxic (Elci 2008)
Hydroelectric dams also greatly reduces the water self-purification capacity
According to Wei et al (2009) water self-purification mechanisms are affected by the
physical chemical and biotic processes in a reservoir However dam construction affects
all of the processes as the flow regime water quality and biotic community in the river In
other words dams slow down the river flow capacity block the river continuum and raise
7
water temperature which decreases the water self-purification capacity (Wei et aI 2009)
In a study done in China by Wei et al (2009) it is recorded that the Manwan-Dachaosan
dam has higher ammonia-nitrogen concentration due to the decreased water selfshy
purification capacity as compared to the pre-dam period This suggests that damming has
severely decreased the water self-purification capacity as it blocked the river continuum
8
30 Materials and Methods
31 Study Site
Bakun Hydroelectric Reservoir is a man-made reservoir which is located 60 km
west of Belaga Sarawak Malaysia (Figure 1) The dam was formed after the
impoundment of Balui River The reservoir has a catchment area of 14750 km2 and a total
capacity 43800000 m3 with a surface area of 695 km2 The dam is the second tallest
concrete-faced rockfill dam in the world
Three sampling stations namely stations 1 2 and 3 was selected in the reservoir
Station 1 is at the inundated estuary of the Linau River Station 2 is at the inundated Balui
River and Station 3 is located in the inundated Balui River as well but nearer to the dam
At each station sampling was conducted at 6 levels namely the subsurface 10m 20m
30m 4Om and 50m depths The coordinates of Bakun dam is at longitude 02deg45 23N and
latitude 114deg0347E The coordinates of every sampling station were recorded by the
Global Positioning System (GARMIN GPSMAP 62S) (Table 1) Sampling was carried
out twice the first sampling was from 21 SI August to 27th August 2015 and the second
sampling was 5th November to 11 th November 2015
9
i
EAST MALAYSIA
o
I
-I River I
-I Flooded Area
Station
0 Dam
kill I
Figure 1 Location of the three sampling stations at Bakun Reservoir
Table 1 Coordinates and locations of sampling stations
Station Coordinates Location
N 02deg 39 322 E 114deg 03 295 Estuary of Linau River
2 N 02deg 43 344 E 114deg 01 442 Balui River
3 N 02deg 43 4135 E 114deg 03 340 Further downstream of Balui River
10
32 Water samples
The water samples were taken using Van Dorn water sampler at all three stations
and were taken at 6 different depths which are the subsurface (02m) 10m 20m 30m 40m
and 5Om At each station three replicates of water samples were taken back for laboratory
analysis Water samples were kept in 2 L polyethylene water bottles that has been acid
washed and were stored in cooler box filled with ice All samples were taken to the
laboratory for further analysis
33 Water quality parameters measured in-situ
Temperature dissolved oxygen (DO) pH electrical conductivity total dissolved
solids (TDS) and turbidity were taken using YSI Multiparameter Water Quality 6920 V2
The depths of each station were measured using depth finder Water transparency was also
measured using secchi disc at each station
34 Water quality parameters analysed ex-situ
341 Biochemical oxygen demand in five days (BODs)
BODs were determined by filling water samples into 300 ml BOD bottles DO
readings of the water samples were measured from the bottles All BOD bottles were
wrapped with aluminum foil to prevent light penetration and were kept in a cooler box for
5 days The initial DO value was recorded as DJ and on the 5th day the DO reading was
recorded as Ds The formula that was used for measuring BODs follows the protocol
outlined by APHA (1998)
11
BOD5 (mglL) = DJ - D5
Where DJ = Initial DO of sample immediately after preparation (mglL)
D5 = DO value after 5 days incubation at 25degC (mglL)
342 Total suspended solids (TSS)
Total suspended solids were analyzed using standard method APHA (1998) For
TSS analysis there was pre-fieldtrip sampling method and post-fieldtrip method For preshy
fieldtrip method glass fibre filter paper (GFIC 47 nun diameter 045 Ilm membrane) were
soaked in distilled water Each filter paper is placed on a piece of aluminum foil and was
dried in the oven at 103degC - 105degC overnight Filter paper then was allowed to cool for 10
minutes before weighing it using an analytical balance (ACCULAB ALC - 210) The
initial weight was recorded For post-fieldtrip method the glass fibre paper was placed on
the inter-plate of the filter funnel using a pair of forceps A known volume of water
samples was filtered using a vacuum pump After that filter paper was removed from the
filtration funnel and was placed back into the aluminum foil Filter paper was dried in the
oven at 103degC - 105degC overnight (APHA 1998) Filter paper was then taken out of the
oven and allowed to cool until room temperature before weighing The final reading of the
filtered glass fibre paper was recorded and TSS was calculated using the formula
w -wTSS (mglL) = J I
V
Where W = Initial weight of filter paper
WJ = Final weight of filter paper
V = Volume of water samples filtered (L)
12
4 Chlorophyll-a
The concentration of chlorophyll-a In the water samples were analyzed using
staDdard method APHA (1998) For chlorophyll-a analysis water samples were filtered
using vacuum pump Filter paper containing chlorophyll-a was taken from the vacuum
pump for analysis The samples were grinded by using a grinder and 5 - 6 mL of 90
acetone was added into the mortar Samples were grinded for about 5 minutes and all
materials in the mortar were placed into a capped test tube Ninety percent acetone was
added into the test tube to make up the volume to 10mL Test tube was folded with
aluminum foil and was placed in the refrigerator for 4 - 18 hours to facilitate complete
extraction of the pigments The liquid extracted was transferred into the centrifuge tube
The samples were placed into a centrifuge for about 10 minutes under 3000 rpm Optical
density was determined using spectrophotometer at wavelength of 750 nm 664 run 647
am and 630 nm Each extinctions for small turbidity blank was corrected by subtracting
750 nm from 664 nm and 630 run absorptions
The concentration of chlorophyll-a in the extract of the pigment after correction was
calculated using
Where E = the absorption in the respective wavelength
After determining the concentration of the chlorophyll-a in the extract the amount of
cblorophyll-a in the pigment per unit volume of water filtered was calculated as follows
13
Ca(v)Chlorophyll-a (Jg IL) = - shyv
Where Co = Chlorophyll-a pigment concentration in JgmL
v = Volume ofacetone in mL
v = Volume of samples in L
344 Ammonia-nitrogen (NH3-N)
For ammonia-nitrogen (NH3-N) the concentration was determined using standard
method 8038 Nessler Method (HACH 2000) A 25 mL prepared sample and 25 mL of
deionized water were filled into a separate 25 mL mixing graduated cylinder Three drops
of Mineral Stabilizer were added to both of the cylinders The cylinders were inverted
several times to mix the content After that 1 mL of Nessler reagent was pipetted into both
of the cylinders and the cylinders were inverted several times to mix the content A one-
minute reaction was started Both the solutions were poured into a square sample cell A
yellow colour formation will indicate the presence of ammonia When the timer expired
the blank was inserted into the square sample cell with the fill line facing the right The
reading at 425 run was zeroed The prepared sample was inserted into the cell holder of
Spectrophotometer DR 2800 (HACH 2000) with the fill line facing right and the reading
displayed was recorded
345 Nitrate (NO)-)
For nitrate analysis the concentration was determined using standard method 8192
Cadmium Reduction Method (HACH 2000) The sample was filled until the 15 mL mark
of a 25 mL graduated measuring cylinder The content of one Nitra Ver6 Nitrate Reagent
Pillow Powder was added into the cylinder and capped with a stopper The cylinder was
14
I
Figure
Figure 1
Figure 2
Figure 3
Figure 4
Figure 5
Figure 6
Figure 7
Figure 8
Figure 9
Figure 10
Figure 11
Figure 12
Figure 13
Figure 14
Figure 15
Figure 16
Figure 17
Figure 18
Figure 19
Figure 20
Figure 21
Figure 22
Figure 23
Figure 24
Figure 25
Figure 26
Figure 27
Figure 28
Figure 29
Figure 30
Figure 31
-
LIST OF FIGURES
Title Page
The location of sampling stations at Bakun Dam Sarawak 10
19
Temperature values in November 2015
Temperature values in August 2015
21
Temperature profile in August 2015 22
Temperature profile in November 2015 23
PH values in August 2015 24
PH values in November 2015 25
Turbidity values in August 2015 27
Turbidity values in November 2015 28
Water conductivity values in August 2015 29
Water conductivity values in November 2015 30
Dissolved oxygen (DO) values in August 2015 32
Dissolved oxygen (DO) values in November 2015 33
Dissolved oxygen (DO) profile in August 2015 34
Dissolved oxygen (DO) profile in November 2015 34
Chlorophyll-a values in August 2015 36
Chlorophyll-a values in November 2015 37
BODs values in August 2015 38
BODs values in November 2015 39
Nitrate-N values in August 2015 41
Nitrate-N values in November 2015 41
Nitrite-N values in August 2015 43
Nitrite-N values in November 2015 43
Ammonia-N values in August 2015 45
Ammonia-N values in November 2015 45
Silica values in August 2015 47
Silica values in November 2015 47
Orthophosphate values in August 2015 49
Orthophosphate values in November 2015 49
TSS values in August 2015 51
TSS values in November 2015 51
VI
LIST OF TABLES
Table Title Page
Table 1 Coordinates and locations of sampling stations 10
Table 2 Water depth and transparency values in August 2015 18
Table 3 Classification of water quality parameters according to NWQS 64
VII
LIST OF ABBREVIATIONS
degC Degree Celsius
lm Micrometre
BOD Biological Oxygen Demand
DO Dissolved Oxygen
km2 Kilometre Square
3m Cubic Metre
mgL Milligram per litre
mL Millilitre
L Litre
nm Nanometre
mm Millimetre
pH Potential of Hydrogen
N Nitrogen
N02- Nitrite
N03- Nitrate
P04 3- Orthophosphate
Si04 Silica
NH3-N Ammonia-Nitrogen
TSS Total Suspended Solids
TDS Total Dissolved Solids
GPS Global Positioning System
VIII
10 Introduction
Hydroelectric dams have been constructed worldwide to provide an alternative
energy source as petroleum in the world is depleting and is not renewable Hence
impoundment started around the world to collect water bodies to act as a reservoir
Reservoirs formed by impoundment they will undergo great changes in water
quality (Chapman 1996) This was observed in tropical reservoirs such as Feitsui
Reservoir in Taiwan (Chang and Wen 1997) and Lake Brokopondo in Surinam (Van der
Heide 1978) and also temperate reservoirs such as Butgenbuch Reservoir in Belgium
(Lourantou et aI 2007) and Bureye Reservoir in Russia (Shesterkin 2008) This happens
because of the impact of inundated soil and vegetation including the standing forest on the
water quality such as pH level and dissolved oxygen concentration (Van der Heide 1978
Shesterkin 2008) which is essential for aquatic life
In Malaysia hydroelectric dams have been constructed to meet the energy needs
and security Among the hydroelectric dams that have been built in Sarawak is the Bakun
Hydroelectric Dam Construction of the dam started in 2002 It is located about sixty
kilometers from the town of Belaga and is situated on the Balui River Bakun
Hydroelectric Dam is the largest hydropower project in Malaysia that can produce up to
2400 MW of electricity (httpwwwsarawakenergycomrny)Itis the second highest
concrete faced rockfill dam in the world with an area of 695 square kilometers and a height
of 207 meters (httpwwwsarawakenergycomrny) Research on the characteristics of
physico-chemical water quality at Bakun Dam has been conducted by Nyanti (2012)
However it was conducted during the filling phase of the hydroelectric dam which is
fifteen months after impoundment has started Since then there has been no publishing
literature on the characteristics of the water quality
1
Hence the goal of this study is to obtain detailed information on the physicoshy
chemical water properties of the Bakun Hydroelectric Dam 3 years and 7 months after it
has reached its full supply level Therefore the objectives of this study were
(i) To determine the water quality at six depths at three stations in the
reservOIr
(ii) Compare the characteristics of the water quality among the depths and
stations and
(iii) Determine the changes in water quality characteristics 5 years 6 months
after the dam was impounded
2
jl - - I
20 Literature Review
21 Reservoir
According to Pawar amp Shembekar (2012) water is important and it is the most
abundant resource in the world which man has used for decades Water covers about 70
of the earths surface but only 27 of the total amount is freshwater of which 1 is iceshy
free water in the rivers lakes and atmosphere as biological water It is believed that only
0001 92 of the total water on earth is available for human use (Pawar amp Shembekar
2012) Hence reservoirs are created in order to provide domestic water supply generation
of electricity and aquaculture In Malaysia 63 large reservoirs with a total storage of 25
billion m3 have been constructed (Makhlough 2008)
Water quality in reservoirs is greatly affected by the composition of plant materials
that were submerged during the inundation process In a study done by Ling (2012) water
in the Batang Ai reservoir contains high sulfide concentrations especially at inundated
areas Besides that Nyanti (2012) also reported that the anoxic condition and the acidic
condition in Bakun Dam is due to the decomposition of submerged carbonaceous
materials
Additionally human activities in and around reservoirs and the physical and
chemical properties of water will be affected (Mustapha 2008) Precipitation evaporation
and ground movement can also affect water quality In Batang Ai reservoir the dissolved
oxygen was reported to be lower due to nearby cage aquaculture as it is consumed by
microorganisms in the decomposition of organic matter (Ling 2012)
22 Water quality
Water quality in a reservoir is the physical and chemical limnology of a reservoir
(Sidnei 1992) and includes all physical chemical and biological aspects of water that
3
influence the beneficial usage of water (Mustapha 2008) In reservoirs water quality
deterioration usually comes from excessive nutrient inputs eutrophication acidification
heavy metal contamination organic pollution and obnoxious fishing practices (Mustapha
2008)
Therefore water quality is an important indicator of the ecological status of a
reservoir It is reported that the significant lower dissolved oxygen is recorded due to
higher turbidity and increased suspended solids which affect the dissolution of oxygen
which is brought in by the flood that occurred in Oyun Reservoir (Mustapha 2008)
Additionally in a study done at Bakun Dam turbidity is affected by the suspended solids
from eroded soils from the logging activities in the watershed upstream from the north of
the reservoir (Nyanti 2012)
221 Temperature
Temperature is very important to a reservoir as it affects chemical and biological
activities of aquatic organisms (Sangpal 2011) In a reservoir when the upper layer and
the lower layer have great variation in temperature thermocline will occur Thermal
stratification in deep reservoir is an important natural process which gives significant
effects on water quality The production of ammonia sulphide and algal nutrients are
dependent on the changes in water temperature which subsequently affects the water
quality (Baharim 2011) Besides that vertical distribution and change in water
temperature can affect productivity of the natural organisms in the reservoirs However
the effect varies from reservoir to reservoir According to Li amp Xu (1995) thermocline is
common in reservoirs and usually occurs at the depth of 8m to 23m In a study done by
Nyanti (2012) water temperature in Bakun reservoir was reported to undergo thermocline
as depth increased from subsurface to 18m
4
l I
Pusat Khidmat Maldumat Akadfmil UN nsmMALAYSIA SARAWAI~
222 Dissolved Oxygen (DO)
DO is a very essential environmental factor that affects the entire production of a
reservoir and it is also an important indicator of water quality health of reservoir and also
ecological status as it is used for respiration and in biological and chemical reactions
(Mustapha 2008)
DO fluctuate from reservOIr to reservOIr and it is usually affected by
photosynthesis respiration and diel fluctuation In a study done by Ling (2012) it was
reported that the DO is higher at 05m depth at a11 stations in Batang Ai reservoir ranging
from 47 to 87 mgL due to the high phytoplankton photosynthesis rate An example of
diel fluctuation is shown in Kontagora reservoir where the DO is higher during the dry
season than the rainy season (Ibrahim 2009) This shows that the fluctuation also depends
on temperature depth wind and amount of biological activities such as decomposition In
Bakon Dam DO is high at the subsurface but dropped drastically until anoxic level at
depth 2 - 4m 2 years after impoundment and this is mainly due to the decomposition of
organic matter (Nyanti 2012)
223 pH
pH that is suitable for optimal production for inland waters should be about 65 to
85 (Ibrahim 2009) However changes in pH can affect the transfer of nutrients and affect
the condition ofwater quality (Li amp Xu 1995)
Fluctuations in pH can be caused by the photosynthesis process of phytoplanktons
as was reported in Batang Ai reservoir where all pH value was above 7 (Ling 2012)
Carbon dioxide produced by photosynthesis process will alter the pH of water as carbonic
acid will be formed when carbon dioxide reacts with water (Sangpal 2011)
5
Acidic effects in reservoirs can be caused by the transfer of cooler water from other
tributaries where the water is denser and lower in pH Nyanti (2012) reported the pH value
at Bakundam were all acidic ranging from 517-592 and the overall trend of pH in Bakun
dam decreases from upstream towards the dam (Nyanti et aI 2012)
224 Nutrients
Reservoirs are often have higher chances of getting higher element loading
compared to natural lakes as they have greater catchment area and high inflow rates
(Pawar amp Shembekar 2012) The concentration of nutrients varies from reservoir to
reservoir due to the differences in soil and vegetation in the catchment area (Li amp Xu
1995) Nutrients such as nitrates phosphates silicates and iron are important nutrients
required for aquatic growth but may also cause eutrophication and water quality problems
(Li amp Xu 1995) Eutrophication can occur easily in reservoir due to high input of nutrients
into the water and water quality of reservoir will be affected giving rise to unpleasant taste
and odour and affects the dissolution of other gases especially dissolved oxygen
(Mustapha 2008) According to Nyanti (2012) strong rotten egg smell discovered in
Bakun dam indicates high volume of hydrogen sulfide This observation is also supported
by Lourantou (2007) where an irritating odour smell occurs at a reservoir in Belgium
Nutrients input can also be affected by weather and season where nitrate was recorded at
higher values in Ujjani reservoir during post-monsoon season This may be caused by the
oxidation of nitrifying bacteria and biological nitrification Sulphate concentrations in the
dam were very high in both pre and post-monsoon which were probably caused by the
mineral rocks anthropogenically added and also by rain (Sangpal 2011) The phosphate
levels were found to be lower during the pre-monsoon and higher during the postshy
6
monsoon Phosphate leads to eutrophication that can cause unpleasant taste and odour to
the water (Sangpal 2011)
23 Impacts of hydroelectric dams on water quality
Hydroelectric dam has a direct impact to the water quality as it uses the flow rate of
a water course to produce electricity The building of hydroelectric dams has direct impact
towards the chemical thermal and physical parameters of the water body (Bunea 2012)
According to a study done by Bunea (2012) hydroelectric dams have relatively low DO
concentration mostly lower than 50 mglL because of the organic sediments that are left at
the bottom of the reservoir bottom during the initial filing Organic substances left at the
bottom of the reservoir bottom floor will absorb oxygen from the water in order to
decompose producing hydrogen sulphide carbon dioxide and methane (Bunea 2012)
Due to damming for hydroelectric generation water in a reservoir will undergo
stagnation which will lead to thermal stratification (Bunea 2012) According to a study
done by Elci (2008) thermal stratification of the reservoir involves the higher temperature
at the surface and lower temperatures at the bottom which suggests that thermal energy is
very slowly transferred to the bottom layers of the water body Thermal stratification act as
a barrier to re train mixing of the water column This causes an uneven concentration of
nutrients lack of light for photosynthesis at the hypolimnion and the water column may
become anoxic (Elci 2008)
Hydroelectric dams also greatly reduces the water self-purification capacity
According to Wei et al (2009) water self-purification mechanisms are affected by the
physical chemical and biotic processes in a reservoir However dam construction affects
all of the processes as the flow regime water quality and biotic community in the river In
other words dams slow down the river flow capacity block the river continuum and raise
7
water temperature which decreases the water self-purification capacity (Wei et aI 2009)
In a study done in China by Wei et al (2009) it is recorded that the Manwan-Dachaosan
dam has higher ammonia-nitrogen concentration due to the decreased water selfshy
purification capacity as compared to the pre-dam period This suggests that damming has
severely decreased the water self-purification capacity as it blocked the river continuum
8
30 Materials and Methods
31 Study Site
Bakun Hydroelectric Reservoir is a man-made reservoir which is located 60 km
west of Belaga Sarawak Malaysia (Figure 1) The dam was formed after the
impoundment of Balui River The reservoir has a catchment area of 14750 km2 and a total
capacity 43800000 m3 with a surface area of 695 km2 The dam is the second tallest
concrete-faced rockfill dam in the world
Three sampling stations namely stations 1 2 and 3 was selected in the reservoir
Station 1 is at the inundated estuary of the Linau River Station 2 is at the inundated Balui
River and Station 3 is located in the inundated Balui River as well but nearer to the dam
At each station sampling was conducted at 6 levels namely the subsurface 10m 20m
30m 4Om and 50m depths The coordinates of Bakun dam is at longitude 02deg45 23N and
latitude 114deg0347E The coordinates of every sampling station were recorded by the
Global Positioning System (GARMIN GPSMAP 62S) (Table 1) Sampling was carried
out twice the first sampling was from 21 SI August to 27th August 2015 and the second
sampling was 5th November to 11 th November 2015
9
i
EAST MALAYSIA
o
I
-I River I
-I Flooded Area
Station
0 Dam
kill I
Figure 1 Location of the three sampling stations at Bakun Reservoir
Table 1 Coordinates and locations of sampling stations
Station Coordinates Location
N 02deg 39 322 E 114deg 03 295 Estuary of Linau River
2 N 02deg 43 344 E 114deg 01 442 Balui River
3 N 02deg 43 4135 E 114deg 03 340 Further downstream of Balui River
10
32 Water samples
The water samples were taken using Van Dorn water sampler at all three stations
and were taken at 6 different depths which are the subsurface (02m) 10m 20m 30m 40m
and 5Om At each station three replicates of water samples were taken back for laboratory
analysis Water samples were kept in 2 L polyethylene water bottles that has been acid
washed and were stored in cooler box filled with ice All samples were taken to the
laboratory for further analysis
33 Water quality parameters measured in-situ
Temperature dissolved oxygen (DO) pH electrical conductivity total dissolved
solids (TDS) and turbidity were taken using YSI Multiparameter Water Quality 6920 V2
The depths of each station were measured using depth finder Water transparency was also
measured using secchi disc at each station
34 Water quality parameters analysed ex-situ
341 Biochemical oxygen demand in five days (BODs)
BODs were determined by filling water samples into 300 ml BOD bottles DO
readings of the water samples were measured from the bottles All BOD bottles were
wrapped with aluminum foil to prevent light penetration and were kept in a cooler box for
5 days The initial DO value was recorded as DJ and on the 5th day the DO reading was
recorded as Ds The formula that was used for measuring BODs follows the protocol
outlined by APHA (1998)
11
BOD5 (mglL) = DJ - D5
Where DJ = Initial DO of sample immediately after preparation (mglL)
D5 = DO value after 5 days incubation at 25degC (mglL)
342 Total suspended solids (TSS)
Total suspended solids were analyzed using standard method APHA (1998) For
TSS analysis there was pre-fieldtrip sampling method and post-fieldtrip method For preshy
fieldtrip method glass fibre filter paper (GFIC 47 nun diameter 045 Ilm membrane) were
soaked in distilled water Each filter paper is placed on a piece of aluminum foil and was
dried in the oven at 103degC - 105degC overnight Filter paper then was allowed to cool for 10
minutes before weighing it using an analytical balance (ACCULAB ALC - 210) The
initial weight was recorded For post-fieldtrip method the glass fibre paper was placed on
the inter-plate of the filter funnel using a pair of forceps A known volume of water
samples was filtered using a vacuum pump After that filter paper was removed from the
filtration funnel and was placed back into the aluminum foil Filter paper was dried in the
oven at 103degC - 105degC overnight (APHA 1998) Filter paper was then taken out of the
oven and allowed to cool until room temperature before weighing The final reading of the
filtered glass fibre paper was recorded and TSS was calculated using the formula
w -wTSS (mglL) = J I
V
Where W = Initial weight of filter paper
WJ = Final weight of filter paper
V = Volume of water samples filtered (L)
12
4 Chlorophyll-a
The concentration of chlorophyll-a In the water samples were analyzed using
staDdard method APHA (1998) For chlorophyll-a analysis water samples were filtered
using vacuum pump Filter paper containing chlorophyll-a was taken from the vacuum
pump for analysis The samples were grinded by using a grinder and 5 - 6 mL of 90
acetone was added into the mortar Samples were grinded for about 5 minutes and all
materials in the mortar were placed into a capped test tube Ninety percent acetone was
added into the test tube to make up the volume to 10mL Test tube was folded with
aluminum foil and was placed in the refrigerator for 4 - 18 hours to facilitate complete
extraction of the pigments The liquid extracted was transferred into the centrifuge tube
The samples were placed into a centrifuge for about 10 minutes under 3000 rpm Optical
density was determined using spectrophotometer at wavelength of 750 nm 664 run 647
am and 630 nm Each extinctions for small turbidity blank was corrected by subtracting
750 nm from 664 nm and 630 run absorptions
The concentration of chlorophyll-a in the extract of the pigment after correction was
calculated using
Where E = the absorption in the respective wavelength
After determining the concentration of the chlorophyll-a in the extract the amount of
cblorophyll-a in the pigment per unit volume of water filtered was calculated as follows
13
Ca(v)Chlorophyll-a (Jg IL) = - shyv
Where Co = Chlorophyll-a pigment concentration in JgmL
v = Volume ofacetone in mL
v = Volume of samples in L
344 Ammonia-nitrogen (NH3-N)
For ammonia-nitrogen (NH3-N) the concentration was determined using standard
method 8038 Nessler Method (HACH 2000) A 25 mL prepared sample and 25 mL of
deionized water were filled into a separate 25 mL mixing graduated cylinder Three drops
of Mineral Stabilizer were added to both of the cylinders The cylinders were inverted
several times to mix the content After that 1 mL of Nessler reagent was pipetted into both
of the cylinders and the cylinders were inverted several times to mix the content A one-
minute reaction was started Both the solutions were poured into a square sample cell A
yellow colour formation will indicate the presence of ammonia When the timer expired
the blank was inserted into the square sample cell with the fill line facing the right The
reading at 425 run was zeroed The prepared sample was inserted into the cell holder of
Spectrophotometer DR 2800 (HACH 2000) with the fill line facing right and the reading
displayed was recorded
345 Nitrate (NO)-)
For nitrate analysis the concentration was determined using standard method 8192
Cadmium Reduction Method (HACH 2000) The sample was filled until the 15 mL mark
of a 25 mL graduated measuring cylinder The content of one Nitra Ver6 Nitrate Reagent
Pillow Powder was added into the cylinder and capped with a stopper The cylinder was
14
LIST OF TABLES
Table Title Page
Table 1 Coordinates and locations of sampling stations 10
Table 2 Water depth and transparency values in August 2015 18
Table 3 Classification of water quality parameters according to NWQS 64
VII
LIST OF ABBREVIATIONS
degC Degree Celsius
lm Micrometre
BOD Biological Oxygen Demand
DO Dissolved Oxygen
km2 Kilometre Square
3m Cubic Metre
mgL Milligram per litre
mL Millilitre
L Litre
nm Nanometre
mm Millimetre
pH Potential of Hydrogen
N Nitrogen
N02- Nitrite
N03- Nitrate
P04 3- Orthophosphate
Si04 Silica
NH3-N Ammonia-Nitrogen
TSS Total Suspended Solids
TDS Total Dissolved Solids
GPS Global Positioning System
VIII
10 Introduction
Hydroelectric dams have been constructed worldwide to provide an alternative
energy source as petroleum in the world is depleting and is not renewable Hence
impoundment started around the world to collect water bodies to act as a reservoir
Reservoirs formed by impoundment they will undergo great changes in water
quality (Chapman 1996) This was observed in tropical reservoirs such as Feitsui
Reservoir in Taiwan (Chang and Wen 1997) and Lake Brokopondo in Surinam (Van der
Heide 1978) and also temperate reservoirs such as Butgenbuch Reservoir in Belgium
(Lourantou et aI 2007) and Bureye Reservoir in Russia (Shesterkin 2008) This happens
because of the impact of inundated soil and vegetation including the standing forest on the
water quality such as pH level and dissolved oxygen concentration (Van der Heide 1978
Shesterkin 2008) which is essential for aquatic life
In Malaysia hydroelectric dams have been constructed to meet the energy needs
and security Among the hydroelectric dams that have been built in Sarawak is the Bakun
Hydroelectric Dam Construction of the dam started in 2002 It is located about sixty
kilometers from the town of Belaga and is situated on the Balui River Bakun
Hydroelectric Dam is the largest hydropower project in Malaysia that can produce up to
2400 MW of electricity (httpwwwsarawakenergycomrny)Itis the second highest
concrete faced rockfill dam in the world with an area of 695 square kilometers and a height
of 207 meters (httpwwwsarawakenergycomrny) Research on the characteristics of
physico-chemical water quality at Bakun Dam has been conducted by Nyanti (2012)
However it was conducted during the filling phase of the hydroelectric dam which is
fifteen months after impoundment has started Since then there has been no publishing
literature on the characteristics of the water quality
1
Hence the goal of this study is to obtain detailed information on the physicoshy
chemical water properties of the Bakun Hydroelectric Dam 3 years and 7 months after it
has reached its full supply level Therefore the objectives of this study were
(i) To determine the water quality at six depths at three stations in the
reservOIr
(ii) Compare the characteristics of the water quality among the depths and
stations and
(iii) Determine the changes in water quality characteristics 5 years 6 months
after the dam was impounded
2
jl - - I
20 Literature Review
21 Reservoir
According to Pawar amp Shembekar (2012) water is important and it is the most
abundant resource in the world which man has used for decades Water covers about 70
of the earths surface but only 27 of the total amount is freshwater of which 1 is iceshy
free water in the rivers lakes and atmosphere as biological water It is believed that only
0001 92 of the total water on earth is available for human use (Pawar amp Shembekar
2012) Hence reservoirs are created in order to provide domestic water supply generation
of electricity and aquaculture In Malaysia 63 large reservoirs with a total storage of 25
billion m3 have been constructed (Makhlough 2008)
Water quality in reservoirs is greatly affected by the composition of plant materials
that were submerged during the inundation process In a study done by Ling (2012) water
in the Batang Ai reservoir contains high sulfide concentrations especially at inundated
areas Besides that Nyanti (2012) also reported that the anoxic condition and the acidic
condition in Bakun Dam is due to the decomposition of submerged carbonaceous
materials
Additionally human activities in and around reservoirs and the physical and
chemical properties of water will be affected (Mustapha 2008) Precipitation evaporation
and ground movement can also affect water quality In Batang Ai reservoir the dissolved
oxygen was reported to be lower due to nearby cage aquaculture as it is consumed by
microorganisms in the decomposition of organic matter (Ling 2012)
22 Water quality
Water quality in a reservoir is the physical and chemical limnology of a reservoir
(Sidnei 1992) and includes all physical chemical and biological aspects of water that
3
influence the beneficial usage of water (Mustapha 2008) In reservoirs water quality
deterioration usually comes from excessive nutrient inputs eutrophication acidification
heavy metal contamination organic pollution and obnoxious fishing practices (Mustapha
2008)
Therefore water quality is an important indicator of the ecological status of a
reservoir It is reported that the significant lower dissolved oxygen is recorded due to
higher turbidity and increased suspended solids which affect the dissolution of oxygen
which is brought in by the flood that occurred in Oyun Reservoir (Mustapha 2008)
Additionally in a study done at Bakun Dam turbidity is affected by the suspended solids
from eroded soils from the logging activities in the watershed upstream from the north of
the reservoir (Nyanti 2012)
221 Temperature
Temperature is very important to a reservoir as it affects chemical and biological
activities of aquatic organisms (Sangpal 2011) In a reservoir when the upper layer and
the lower layer have great variation in temperature thermocline will occur Thermal
stratification in deep reservoir is an important natural process which gives significant
effects on water quality The production of ammonia sulphide and algal nutrients are
dependent on the changes in water temperature which subsequently affects the water
quality (Baharim 2011) Besides that vertical distribution and change in water
temperature can affect productivity of the natural organisms in the reservoirs However
the effect varies from reservoir to reservoir According to Li amp Xu (1995) thermocline is
common in reservoirs and usually occurs at the depth of 8m to 23m In a study done by
Nyanti (2012) water temperature in Bakun reservoir was reported to undergo thermocline
as depth increased from subsurface to 18m
4
l I
Pusat Khidmat Maldumat Akadfmil UN nsmMALAYSIA SARAWAI~
222 Dissolved Oxygen (DO)
DO is a very essential environmental factor that affects the entire production of a
reservoir and it is also an important indicator of water quality health of reservoir and also
ecological status as it is used for respiration and in biological and chemical reactions
(Mustapha 2008)
DO fluctuate from reservOIr to reservOIr and it is usually affected by
photosynthesis respiration and diel fluctuation In a study done by Ling (2012) it was
reported that the DO is higher at 05m depth at a11 stations in Batang Ai reservoir ranging
from 47 to 87 mgL due to the high phytoplankton photosynthesis rate An example of
diel fluctuation is shown in Kontagora reservoir where the DO is higher during the dry
season than the rainy season (Ibrahim 2009) This shows that the fluctuation also depends
on temperature depth wind and amount of biological activities such as decomposition In
Bakon Dam DO is high at the subsurface but dropped drastically until anoxic level at
depth 2 - 4m 2 years after impoundment and this is mainly due to the decomposition of
organic matter (Nyanti 2012)
223 pH
pH that is suitable for optimal production for inland waters should be about 65 to
85 (Ibrahim 2009) However changes in pH can affect the transfer of nutrients and affect
the condition ofwater quality (Li amp Xu 1995)
Fluctuations in pH can be caused by the photosynthesis process of phytoplanktons
as was reported in Batang Ai reservoir where all pH value was above 7 (Ling 2012)
Carbon dioxide produced by photosynthesis process will alter the pH of water as carbonic
acid will be formed when carbon dioxide reacts with water (Sangpal 2011)
5
Acidic effects in reservoirs can be caused by the transfer of cooler water from other
tributaries where the water is denser and lower in pH Nyanti (2012) reported the pH value
at Bakundam were all acidic ranging from 517-592 and the overall trend of pH in Bakun
dam decreases from upstream towards the dam (Nyanti et aI 2012)
224 Nutrients
Reservoirs are often have higher chances of getting higher element loading
compared to natural lakes as they have greater catchment area and high inflow rates
(Pawar amp Shembekar 2012) The concentration of nutrients varies from reservoir to
reservoir due to the differences in soil and vegetation in the catchment area (Li amp Xu
1995) Nutrients such as nitrates phosphates silicates and iron are important nutrients
required for aquatic growth but may also cause eutrophication and water quality problems
(Li amp Xu 1995) Eutrophication can occur easily in reservoir due to high input of nutrients
into the water and water quality of reservoir will be affected giving rise to unpleasant taste
and odour and affects the dissolution of other gases especially dissolved oxygen
(Mustapha 2008) According to Nyanti (2012) strong rotten egg smell discovered in
Bakun dam indicates high volume of hydrogen sulfide This observation is also supported
by Lourantou (2007) where an irritating odour smell occurs at a reservoir in Belgium
Nutrients input can also be affected by weather and season where nitrate was recorded at
higher values in Ujjani reservoir during post-monsoon season This may be caused by the
oxidation of nitrifying bacteria and biological nitrification Sulphate concentrations in the
dam were very high in both pre and post-monsoon which were probably caused by the
mineral rocks anthropogenically added and also by rain (Sangpal 2011) The phosphate
levels were found to be lower during the pre-monsoon and higher during the postshy
6
monsoon Phosphate leads to eutrophication that can cause unpleasant taste and odour to
the water (Sangpal 2011)
23 Impacts of hydroelectric dams on water quality
Hydroelectric dam has a direct impact to the water quality as it uses the flow rate of
a water course to produce electricity The building of hydroelectric dams has direct impact
towards the chemical thermal and physical parameters of the water body (Bunea 2012)
According to a study done by Bunea (2012) hydroelectric dams have relatively low DO
concentration mostly lower than 50 mglL because of the organic sediments that are left at
the bottom of the reservoir bottom during the initial filing Organic substances left at the
bottom of the reservoir bottom floor will absorb oxygen from the water in order to
decompose producing hydrogen sulphide carbon dioxide and methane (Bunea 2012)
Due to damming for hydroelectric generation water in a reservoir will undergo
stagnation which will lead to thermal stratification (Bunea 2012) According to a study
done by Elci (2008) thermal stratification of the reservoir involves the higher temperature
at the surface and lower temperatures at the bottom which suggests that thermal energy is
very slowly transferred to the bottom layers of the water body Thermal stratification act as
a barrier to re train mixing of the water column This causes an uneven concentration of
nutrients lack of light for photosynthesis at the hypolimnion and the water column may
become anoxic (Elci 2008)
Hydroelectric dams also greatly reduces the water self-purification capacity
According to Wei et al (2009) water self-purification mechanisms are affected by the
physical chemical and biotic processes in a reservoir However dam construction affects
all of the processes as the flow regime water quality and biotic community in the river In
other words dams slow down the river flow capacity block the river continuum and raise
7
water temperature which decreases the water self-purification capacity (Wei et aI 2009)
In a study done in China by Wei et al (2009) it is recorded that the Manwan-Dachaosan
dam has higher ammonia-nitrogen concentration due to the decreased water selfshy
purification capacity as compared to the pre-dam period This suggests that damming has
severely decreased the water self-purification capacity as it blocked the river continuum
8
30 Materials and Methods
31 Study Site
Bakun Hydroelectric Reservoir is a man-made reservoir which is located 60 km
west of Belaga Sarawak Malaysia (Figure 1) The dam was formed after the
impoundment of Balui River The reservoir has a catchment area of 14750 km2 and a total
capacity 43800000 m3 with a surface area of 695 km2 The dam is the second tallest
concrete-faced rockfill dam in the world
Three sampling stations namely stations 1 2 and 3 was selected in the reservoir
Station 1 is at the inundated estuary of the Linau River Station 2 is at the inundated Balui
River and Station 3 is located in the inundated Balui River as well but nearer to the dam
At each station sampling was conducted at 6 levels namely the subsurface 10m 20m
30m 4Om and 50m depths The coordinates of Bakun dam is at longitude 02deg45 23N and
latitude 114deg0347E The coordinates of every sampling station were recorded by the
Global Positioning System (GARMIN GPSMAP 62S) (Table 1) Sampling was carried
out twice the first sampling was from 21 SI August to 27th August 2015 and the second
sampling was 5th November to 11 th November 2015
9
i
EAST MALAYSIA
o
I
-I River I
-I Flooded Area
Station
0 Dam
kill I
Figure 1 Location of the three sampling stations at Bakun Reservoir
Table 1 Coordinates and locations of sampling stations
Station Coordinates Location
N 02deg 39 322 E 114deg 03 295 Estuary of Linau River
2 N 02deg 43 344 E 114deg 01 442 Balui River
3 N 02deg 43 4135 E 114deg 03 340 Further downstream of Balui River
10
32 Water samples
The water samples were taken using Van Dorn water sampler at all three stations
and were taken at 6 different depths which are the subsurface (02m) 10m 20m 30m 40m
and 5Om At each station three replicates of water samples were taken back for laboratory
analysis Water samples were kept in 2 L polyethylene water bottles that has been acid
washed and were stored in cooler box filled with ice All samples were taken to the
laboratory for further analysis
33 Water quality parameters measured in-situ
Temperature dissolved oxygen (DO) pH electrical conductivity total dissolved
solids (TDS) and turbidity were taken using YSI Multiparameter Water Quality 6920 V2
The depths of each station were measured using depth finder Water transparency was also
measured using secchi disc at each station
34 Water quality parameters analysed ex-situ
341 Biochemical oxygen demand in five days (BODs)
BODs were determined by filling water samples into 300 ml BOD bottles DO
readings of the water samples were measured from the bottles All BOD bottles were
wrapped with aluminum foil to prevent light penetration and were kept in a cooler box for
5 days The initial DO value was recorded as DJ and on the 5th day the DO reading was
recorded as Ds The formula that was used for measuring BODs follows the protocol
outlined by APHA (1998)
11
BOD5 (mglL) = DJ - D5
Where DJ = Initial DO of sample immediately after preparation (mglL)
D5 = DO value after 5 days incubation at 25degC (mglL)
342 Total suspended solids (TSS)
Total suspended solids were analyzed using standard method APHA (1998) For
TSS analysis there was pre-fieldtrip sampling method and post-fieldtrip method For preshy
fieldtrip method glass fibre filter paper (GFIC 47 nun diameter 045 Ilm membrane) were
soaked in distilled water Each filter paper is placed on a piece of aluminum foil and was
dried in the oven at 103degC - 105degC overnight Filter paper then was allowed to cool for 10
minutes before weighing it using an analytical balance (ACCULAB ALC - 210) The
initial weight was recorded For post-fieldtrip method the glass fibre paper was placed on
the inter-plate of the filter funnel using a pair of forceps A known volume of water
samples was filtered using a vacuum pump After that filter paper was removed from the
filtration funnel and was placed back into the aluminum foil Filter paper was dried in the
oven at 103degC - 105degC overnight (APHA 1998) Filter paper was then taken out of the
oven and allowed to cool until room temperature before weighing The final reading of the
filtered glass fibre paper was recorded and TSS was calculated using the formula
w -wTSS (mglL) = J I
V
Where W = Initial weight of filter paper
WJ = Final weight of filter paper
V = Volume of water samples filtered (L)
12
4 Chlorophyll-a
The concentration of chlorophyll-a In the water samples were analyzed using
staDdard method APHA (1998) For chlorophyll-a analysis water samples were filtered
using vacuum pump Filter paper containing chlorophyll-a was taken from the vacuum
pump for analysis The samples were grinded by using a grinder and 5 - 6 mL of 90
acetone was added into the mortar Samples were grinded for about 5 minutes and all
materials in the mortar were placed into a capped test tube Ninety percent acetone was
added into the test tube to make up the volume to 10mL Test tube was folded with
aluminum foil and was placed in the refrigerator for 4 - 18 hours to facilitate complete
extraction of the pigments The liquid extracted was transferred into the centrifuge tube
The samples were placed into a centrifuge for about 10 minutes under 3000 rpm Optical
density was determined using spectrophotometer at wavelength of 750 nm 664 run 647
am and 630 nm Each extinctions for small turbidity blank was corrected by subtracting
750 nm from 664 nm and 630 run absorptions
The concentration of chlorophyll-a in the extract of the pigment after correction was
calculated using
Where E = the absorption in the respective wavelength
After determining the concentration of the chlorophyll-a in the extract the amount of
cblorophyll-a in the pigment per unit volume of water filtered was calculated as follows
13
Ca(v)Chlorophyll-a (Jg IL) = - shyv
Where Co = Chlorophyll-a pigment concentration in JgmL
v = Volume ofacetone in mL
v = Volume of samples in L
344 Ammonia-nitrogen (NH3-N)
For ammonia-nitrogen (NH3-N) the concentration was determined using standard
method 8038 Nessler Method (HACH 2000) A 25 mL prepared sample and 25 mL of
deionized water were filled into a separate 25 mL mixing graduated cylinder Three drops
of Mineral Stabilizer were added to both of the cylinders The cylinders were inverted
several times to mix the content After that 1 mL of Nessler reagent was pipetted into both
of the cylinders and the cylinders were inverted several times to mix the content A one-
minute reaction was started Both the solutions were poured into a square sample cell A
yellow colour formation will indicate the presence of ammonia When the timer expired
the blank was inserted into the square sample cell with the fill line facing the right The
reading at 425 run was zeroed The prepared sample was inserted into the cell holder of
Spectrophotometer DR 2800 (HACH 2000) with the fill line facing right and the reading
displayed was recorded
345 Nitrate (NO)-)
For nitrate analysis the concentration was determined using standard method 8192
Cadmium Reduction Method (HACH 2000) The sample was filled until the 15 mL mark
of a 25 mL graduated measuring cylinder The content of one Nitra Ver6 Nitrate Reagent
Pillow Powder was added into the cylinder and capped with a stopper The cylinder was
14
LIST OF ABBREVIATIONS
degC Degree Celsius
lm Micrometre
BOD Biological Oxygen Demand
DO Dissolved Oxygen
km2 Kilometre Square
3m Cubic Metre
mgL Milligram per litre
mL Millilitre
L Litre
nm Nanometre
mm Millimetre
pH Potential of Hydrogen
N Nitrogen
N02- Nitrite
N03- Nitrate
P04 3- Orthophosphate
Si04 Silica
NH3-N Ammonia-Nitrogen
TSS Total Suspended Solids
TDS Total Dissolved Solids
GPS Global Positioning System
VIII
10 Introduction
Hydroelectric dams have been constructed worldwide to provide an alternative
energy source as petroleum in the world is depleting and is not renewable Hence
impoundment started around the world to collect water bodies to act as a reservoir
Reservoirs formed by impoundment they will undergo great changes in water
quality (Chapman 1996) This was observed in tropical reservoirs such as Feitsui
Reservoir in Taiwan (Chang and Wen 1997) and Lake Brokopondo in Surinam (Van der
Heide 1978) and also temperate reservoirs such as Butgenbuch Reservoir in Belgium
(Lourantou et aI 2007) and Bureye Reservoir in Russia (Shesterkin 2008) This happens
because of the impact of inundated soil and vegetation including the standing forest on the
water quality such as pH level and dissolved oxygen concentration (Van der Heide 1978
Shesterkin 2008) which is essential for aquatic life
In Malaysia hydroelectric dams have been constructed to meet the energy needs
and security Among the hydroelectric dams that have been built in Sarawak is the Bakun
Hydroelectric Dam Construction of the dam started in 2002 It is located about sixty
kilometers from the town of Belaga and is situated on the Balui River Bakun
Hydroelectric Dam is the largest hydropower project in Malaysia that can produce up to
2400 MW of electricity (httpwwwsarawakenergycomrny)Itis the second highest
concrete faced rockfill dam in the world with an area of 695 square kilometers and a height
of 207 meters (httpwwwsarawakenergycomrny) Research on the characteristics of
physico-chemical water quality at Bakun Dam has been conducted by Nyanti (2012)
However it was conducted during the filling phase of the hydroelectric dam which is
fifteen months after impoundment has started Since then there has been no publishing
literature on the characteristics of the water quality
1
Hence the goal of this study is to obtain detailed information on the physicoshy
chemical water properties of the Bakun Hydroelectric Dam 3 years and 7 months after it
has reached its full supply level Therefore the objectives of this study were
(i) To determine the water quality at six depths at three stations in the
reservOIr
(ii) Compare the characteristics of the water quality among the depths and
stations and
(iii) Determine the changes in water quality characteristics 5 years 6 months
after the dam was impounded
2
jl - - I
20 Literature Review
21 Reservoir
According to Pawar amp Shembekar (2012) water is important and it is the most
abundant resource in the world which man has used for decades Water covers about 70
of the earths surface but only 27 of the total amount is freshwater of which 1 is iceshy
free water in the rivers lakes and atmosphere as biological water It is believed that only
0001 92 of the total water on earth is available for human use (Pawar amp Shembekar
2012) Hence reservoirs are created in order to provide domestic water supply generation
of electricity and aquaculture In Malaysia 63 large reservoirs with a total storage of 25
billion m3 have been constructed (Makhlough 2008)
Water quality in reservoirs is greatly affected by the composition of plant materials
that were submerged during the inundation process In a study done by Ling (2012) water
in the Batang Ai reservoir contains high sulfide concentrations especially at inundated
areas Besides that Nyanti (2012) also reported that the anoxic condition and the acidic
condition in Bakun Dam is due to the decomposition of submerged carbonaceous
materials
Additionally human activities in and around reservoirs and the physical and
chemical properties of water will be affected (Mustapha 2008) Precipitation evaporation
and ground movement can also affect water quality In Batang Ai reservoir the dissolved
oxygen was reported to be lower due to nearby cage aquaculture as it is consumed by
microorganisms in the decomposition of organic matter (Ling 2012)
22 Water quality
Water quality in a reservoir is the physical and chemical limnology of a reservoir
(Sidnei 1992) and includes all physical chemical and biological aspects of water that
3
influence the beneficial usage of water (Mustapha 2008) In reservoirs water quality
deterioration usually comes from excessive nutrient inputs eutrophication acidification
heavy metal contamination organic pollution and obnoxious fishing practices (Mustapha
2008)
Therefore water quality is an important indicator of the ecological status of a
reservoir It is reported that the significant lower dissolved oxygen is recorded due to
higher turbidity and increased suspended solids which affect the dissolution of oxygen
which is brought in by the flood that occurred in Oyun Reservoir (Mustapha 2008)
Additionally in a study done at Bakun Dam turbidity is affected by the suspended solids
from eroded soils from the logging activities in the watershed upstream from the north of
the reservoir (Nyanti 2012)
221 Temperature
Temperature is very important to a reservoir as it affects chemical and biological
activities of aquatic organisms (Sangpal 2011) In a reservoir when the upper layer and
the lower layer have great variation in temperature thermocline will occur Thermal
stratification in deep reservoir is an important natural process which gives significant
effects on water quality The production of ammonia sulphide and algal nutrients are
dependent on the changes in water temperature which subsequently affects the water
quality (Baharim 2011) Besides that vertical distribution and change in water
temperature can affect productivity of the natural organisms in the reservoirs However
the effect varies from reservoir to reservoir According to Li amp Xu (1995) thermocline is
common in reservoirs and usually occurs at the depth of 8m to 23m In a study done by
Nyanti (2012) water temperature in Bakun reservoir was reported to undergo thermocline
as depth increased from subsurface to 18m
4
l I
Pusat Khidmat Maldumat Akadfmil UN nsmMALAYSIA SARAWAI~
222 Dissolved Oxygen (DO)
DO is a very essential environmental factor that affects the entire production of a
reservoir and it is also an important indicator of water quality health of reservoir and also
ecological status as it is used for respiration and in biological and chemical reactions
(Mustapha 2008)
DO fluctuate from reservOIr to reservOIr and it is usually affected by
photosynthesis respiration and diel fluctuation In a study done by Ling (2012) it was
reported that the DO is higher at 05m depth at a11 stations in Batang Ai reservoir ranging
from 47 to 87 mgL due to the high phytoplankton photosynthesis rate An example of
diel fluctuation is shown in Kontagora reservoir where the DO is higher during the dry
season than the rainy season (Ibrahim 2009) This shows that the fluctuation also depends
on temperature depth wind and amount of biological activities such as decomposition In
Bakon Dam DO is high at the subsurface but dropped drastically until anoxic level at
depth 2 - 4m 2 years after impoundment and this is mainly due to the decomposition of
organic matter (Nyanti 2012)
223 pH
pH that is suitable for optimal production for inland waters should be about 65 to
85 (Ibrahim 2009) However changes in pH can affect the transfer of nutrients and affect
the condition ofwater quality (Li amp Xu 1995)
Fluctuations in pH can be caused by the photosynthesis process of phytoplanktons
as was reported in Batang Ai reservoir where all pH value was above 7 (Ling 2012)
Carbon dioxide produced by photosynthesis process will alter the pH of water as carbonic
acid will be formed when carbon dioxide reacts with water (Sangpal 2011)
5
Acidic effects in reservoirs can be caused by the transfer of cooler water from other
tributaries where the water is denser and lower in pH Nyanti (2012) reported the pH value
at Bakundam were all acidic ranging from 517-592 and the overall trend of pH in Bakun
dam decreases from upstream towards the dam (Nyanti et aI 2012)
224 Nutrients
Reservoirs are often have higher chances of getting higher element loading
compared to natural lakes as they have greater catchment area and high inflow rates
(Pawar amp Shembekar 2012) The concentration of nutrients varies from reservoir to
reservoir due to the differences in soil and vegetation in the catchment area (Li amp Xu
1995) Nutrients such as nitrates phosphates silicates and iron are important nutrients
required for aquatic growth but may also cause eutrophication and water quality problems
(Li amp Xu 1995) Eutrophication can occur easily in reservoir due to high input of nutrients
into the water and water quality of reservoir will be affected giving rise to unpleasant taste
and odour and affects the dissolution of other gases especially dissolved oxygen
(Mustapha 2008) According to Nyanti (2012) strong rotten egg smell discovered in
Bakun dam indicates high volume of hydrogen sulfide This observation is also supported
by Lourantou (2007) where an irritating odour smell occurs at a reservoir in Belgium
Nutrients input can also be affected by weather and season where nitrate was recorded at
higher values in Ujjani reservoir during post-monsoon season This may be caused by the
oxidation of nitrifying bacteria and biological nitrification Sulphate concentrations in the
dam were very high in both pre and post-monsoon which were probably caused by the
mineral rocks anthropogenically added and also by rain (Sangpal 2011) The phosphate
levels were found to be lower during the pre-monsoon and higher during the postshy
6
monsoon Phosphate leads to eutrophication that can cause unpleasant taste and odour to
the water (Sangpal 2011)
23 Impacts of hydroelectric dams on water quality
Hydroelectric dam has a direct impact to the water quality as it uses the flow rate of
a water course to produce electricity The building of hydroelectric dams has direct impact
towards the chemical thermal and physical parameters of the water body (Bunea 2012)
According to a study done by Bunea (2012) hydroelectric dams have relatively low DO
concentration mostly lower than 50 mglL because of the organic sediments that are left at
the bottom of the reservoir bottom during the initial filing Organic substances left at the
bottom of the reservoir bottom floor will absorb oxygen from the water in order to
decompose producing hydrogen sulphide carbon dioxide and methane (Bunea 2012)
Due to damming for hydroelectric generation water in a reservoir will undergo
stagnation which will lead to thermal stratification (Bunea 2012) According to a study
done by Elci (2008) thermal stratification of the reservoir involves the higher temperature
at the surface and lower temperatures at the bottom which suggests that thermal energy is
very slowly transferred to the bottom layers of the water body Thermal stratification act as
a barrier to re train mixing of the water column This causes an uneven concentration of
nutrients lack of light for photosynthesis at the hypolimnion and the water column may
become anoxic (Elci 2008)
Hydroelectric dams also greatly reduces the water self-purification capacity
According to Wei et al (2009) water self-purification mechanisms are affected by the
physical chemical and biotic processes in a reservoir However dam construction affects
all of the processes as the flow regime water quality and biotic community in the river In
other words dams slow down the river flow capacity block the river continuum and raise
7
water temperature which decreases the water self-purification capacity (Wei et aI 2009)
In a study done in China by Wei et al (2009) it is recorded that the Manwan-Dachaosan
dam has higher ammonia-nitrogen concentration due to the decreased water selfshy
purification capacity as compared to the pre-dam period This suggests that damming has
severely decreased the water self-purification capacity as it blocked the river continuum
8
30 Materials and Methods
31 Study Site
Bakun Hydroelectric Reservoir is a man-made reservoir which is located 60 km
west of Belaga Sarawak Malaysia (Figure 1) The dam was formed after the
impoundment of Balui River The reservoir has a catchment area of 14750 km2 and a total
capacity 43800000 m3 with a surface area of 695 km2 The dam is the second tallest
concrete-faced rockfill dam in the world
Three sampling stations namely stations 1 2 and 3 was selected in the reservoir
Station 1 is at the inundated estuary of the Linau River Station 2 is at the inundated Balui
River and Station 3 is located in the inundated Balui River as well but nearer to the dam
At each station sampling was conducted at 6 levels namely the subsurface 10m 20m
30m 4Om and 50m depths The coordinates of Bakun dam is at longitude 02deg45 23N and
latitude 114deg0347E The coordinates of every sampling station were recorded by the
Global Positioning System (GARMIN GPSMAP 62S) (Table 1) Sampling was carried
out twice the first sampling was from 21 SI August to 27th August 2015 and the second
sampling was 5th November to 11 th November 2015
9
i
EAST MALAYSIA
o
I
-I River I
-I Flooded Area
Station
0 Dam
kill I
Figure 1 Location of the three sampling stations at Bakun Reservoir
Table 1 Coordinates and locations of sampling stations
Station Coordinates Location
N 02deg 39 322 E 114deg 03 295 Estuary of Linau River
2 N 02deg 43 344 E 114deg 01 442 Balui River
3 N 02deg 43 4135 E 114deg 03 340 Further downstream of Balui River
10
32 Water samples
The water samples were taken using Van Dorn water sampler at all three stations
and were taken at 6 different depths which are the subsurface (02m) 10m 20m 30m 40m
and 5Om At each station three replicates of water samples were taken back for laboratory
analysis Water samples were kept in 2 L polyethylene water bottles that has been acid
washed and were stored in cooler box filled with ice All samples were taken to the
laboratory for further analysis
33 Water quality parameters measured in-situ
Temperature dissolved oxygen (DO) pH electrical conductivity total dissolved
solids (TDS) and turbidity were taken using YSI Multiparameter Water Quality 6920 V2
The depths of each station were measured using depth finder Water transparency was also
measured using secchi disc at each station
34 Water quality parameters analysed ex-situ
341 Biochemical oxygen demand in five days (BODs)
BODs were determined by filling water samples into 300 ml BOD bottles DO
readings of the water samples were measured from the bottles All BOD bottles were
wrapped with aluminum foil to prevent light penetration and were kept in a cooler box for
5 days The initial DO value was recorded as DJ and on the 5th day the DO reading was
recorded as Ds The formula that was used for measuring BODs follows the protocol
outlined by APHA (1998)
11
BOD5 (mglL) = DJ - D5
Where DJ = Initial DO of sample immediately after preparation (mglL)
D5 = DO value after 5 days incubation at 25degC (mglL)
342 Total suspended solids (TSS)
Total suspended solids were analyzed using standard method APHA (1998) For
TSS analysis there was pre-fieldtrip sampling method and post-fieldtrip method For preshy
fieldtrip method glass fibre filter paper (GFIC 47 nun diameter 045 Ilm membrane) were
soaked in distilled water Each filter paper is placed on a piece of aluminum foil and was
dried in the oven at 103degC - 105degC overnight Filter paper then was allowed to cool for 10
minutes before weighing it using an analytical balance (ACCULAB ALC - 210) The
initial weight was recorded For post-fieldtrip method the glass fibre paper was placed on
the inter-plate of the filter funnel using a pair of forceps A known volume of water
samples was filtered using a vacuum pump After that filter paper was removed from the
filtration funnel and was placed back into the aluminum foil Filter paper was dried in the
oven at 103degC - 105degC overnight (APHA 1998) Filter paper was then taken out of the
oven and allowed to cool until room temperature before weighing The final reading of the
filtered glass fibre paper was recorded and TSS was calculated using the formula
w -wTSS (mglL) = J I
V
Where W = Initial weight of filter paper
WJ = Final weight of filter paper
V = Volume of water samples filtered (L)
12
4 Chlorophyll-a
The concentration of chlorophyll-a In the water samples were analyzed using
staDdard method APHA (1998) For chlorophyll-a analysis water samples were filtered
using vacuum pump Filter paper containing chlorophyll-a was taken from the vacuum
pump for analysis The samples were grinded by using a grinder and 5 - 6 mL of 90
acetone was added into the mortar Samples were grinded for about 5 minutes and all
materials in the mortar were placed into a capped test tube Ninety percent acetone was
added into the test tube to make up the volume to 10mL Test tube was folded with
aluminum foil and was placed in the refrigerator for 4 - 18 hours to facilitate complete
extraction of the pigments The liquid extracted was transferred into the centrifuge tube
The samples were placed into a centrifuge for about 10 minutes under 3000 rpm Optical
density was determined using spectrophotometer at wavelength of 750 nm 664 run 647
am and 630 nm Each extinctions for small turbidity blank was corrected by subtracting
750 nm from 664 nm and 630 run absorptions
The concentration of chlorophyll-a in the extract of the pigment after correction was
calculated using
Where E = the absorption in the respective wavelength
After determining the concentration of the chlorophyll-a in the extract the amount of
cblorophyll-a in the pigment per unit volume of water filtered was calculated as follows
13
Ca(v)Chlorophyll-a (Jg IL) = - shyv
Where Co = Chlorophyll-a pigment concentration in JgmL
v = Volume ofacetone in mL
v = Volume of samples in L
344 Ammonia-nitrogen (NH3-N)
For ammonia-nitrogen (NH3-N) the concentration was determined using standard
method 8038 Nessler Method (HACH 2000) A 25 mL prepared sample and 25 mL of
deionized water were filled into a separate 25 mL mixing graduated cylinder Three drops
of Mineral Stabilizer were added to both of the cylinders The cylinders were inverted
several times to mix the content After that 1 mL of Nessler reagent was pipetted into both
of the cylinders and the cylinders were inverted several times to mix the content A one-
minute reaction was started Both the solutions were poured into a square sample cell A
yellow colour formation will indicate the presence of ammonia When the timer expired
the blank was inserted into the square sample cell with the fill line facing the right The
reading at 425 run was zeroed The prepared sample was inserted into the cell holder of
Spectrophotometer DR 2800 (HACH 2000) with the fill line facing right and the reading
displayed was recorded
345 Nitrate (NO)-)
For nitrate analysis the concentration was determined using standard method 8192
Cadmium Reduction Method (HACH 2000) The sample was filled until the 15 mL mark
of a 25 mL graduated measuring cylinder The content of one Nitra Ver6 Nitrate Reagent
Pillow Powder was added into the cylinder and capped with a stopper The cylinder was
14
10 Introduction
Hydroelectric dams have been constructed worldwide to provide an alternative
energy source as petroleum in the world is depleting and is not renewable Hence
impoundment started around the world to collect water bodies to act as a reservoir
Reservoirs formed by impoundment they will undergo great changes in water
quality (Chapman 1996) This was observed in tropical reservoirs such as Feitsui
Reservoir in Taiwan (Chang and Wen 1997) and Lake Brokopondo in Surinam (Van der
Heide 1978) and also temperate reservoirs such as Butgenbuch Reservoir in Belgium
(Lourantou et aI 2007) and Bureye Reservoir in Russia (Shesterkin 2008) This happens
because of the impact of inundated soil and vegetation including the standing forest on the
water quality such as pH level and dissolved oxygen concentration (Van der Heide 1978
Shesterkin 2008) which is essential for aquatic life
In Malaysia hydroelectric dams have been constructed to meet the energy needs
and security Among the hydroelectric dams that have been built in Sarawak is the Bakun
Hydroelectric Dam Construction of the dam started in 2002 It is located about sixty
kilometers from the town of Belaga and is situated on the Balui River Bakun
Hydroelectric Dam is the largest hydropower project in Malaysia that can produce up to
2400 MW of electricity (httpwwwsarawakenergycomrny)Itis the second highest
concrete faced rockfill dam in the world with an area of 695 square kilometers and a height
of 207 meters (httpwwwsarawakenergycomrny) Research on the characteristics of
physico-chemical water quality at Bakun Dam has been conducted by Nyanti (2012)
However it was conducted during the filling phase of the hydroelectric dam which is
fifteen months after impoundment has started Since then there has been no publishing
literature on the characteristics of the water quality
1
Hence the goal of this study is to obtain detailed information on the physicoshy
chemical water properties of the Bakun Hydroelectric Dam 3 years and 7 months after it
has reached its full supply level Therefore the objectives of this study were
(i) To determine the water quality at six depths at three stations in the
reservOIr
(ii) Compare the characteristics of the water quality among the depths and
stations and
(iii) Determine the changes in water quality characteristics 5 years 6 months
after the dam was impounded
2
jl - - I
20 Literature Review
21 Reservoir
According to Pawar amp Shembekar (2012) water is important and it is the most
abundant resource in the world which man has used for decades Water covers about 70
of the earths surface but only 27 of the total amount is freshwater of which 1 is iceshy
free water in the rivers lakes and atmosphere as biological water It is believed that only
0001 92 of the total water on earth is available for human use (Pawar amp Shembekar
2012) Hence reservoirs are created in order to provide domestic water supply generation
of electricity and aquaculture In Malaysia 63 large reservoirs with a total storage of 25
billion m3 have been constructed (Makhlough 2008)
Water quality in reservoirs is greatly affected by the composition of plant materials
that were submerged during the inundation process In a study done by Ling (2012) water
in the Batang Ai reservoir contains high sulfide concentrations especially at inundated
areas Besides that Nyanti (2012) also reported that the anoxic condition and the acidic
condition in Bakun Dam is due to the decomposition of submerged carbonaceous
materials
Additionally human activities in and around reservoirs and the physical and
chemical properties of water will be affected (Mustapha 2008) Precipitation evaporation
and ground movement can also affect water quality In Batang Ai reservoir the dissolved
oxygen was reported to be lower due to nearby cage aquaculture as it is consumed by
microorganisms in the decomposition of organic matter (Ling 2012)
22 Water quality
Water quality in a reservoir is the physical and chemical limnology of a reservoir
(Sidnei 1992) and includes all physical chemical and biological aspects of water that
3
influence the beneficial usage of water (Mustapha 2008) In reservoirs water quality
deterioration usually comes from excessive nutrient inputs eutrophication acidification
heavy metal contamination organic pollution and obnoxious fishing practices (Mustapha
2008)
Therefore water quality is an important indicator of the ecological status of a
reservoir It is reported that the significant lower dissolved oxygen is recorded due to
higher turbidity and increased suspended solids which affect the dissolution of oxygen
which is brought in by the flood that occurred in Oyun Reservoir (Mustapha 2008)
Additionally in a study done at Bakun Dam turbidity is affected by the suspended solids
from eroded soils from the logging activities in the watershed upstream from the north of
the reservoir (Nyanti 2012)
221 Temperature
Temperature is very important to a reservoir as it affects chemical and biological
activities of aquatic organisms (Sangpal 2011) In a reservoir when the upper layer and
the lower layer have great variation in temperature thermocline will occur Thermal
stratification in deep reservoir is an important natural process which gives significant
effects on water quality The production of ammonia sulphide and algal nutrients are
dependent on the changes in water temperature which subsequently affects the water
quality (Baharim 2011) Besides that vertical distribution and change in water
temperature can affect productivity of the natural organisms in the reservoirs However
the effect varies from reservoir to reservoir According to Li amp Xu (1995) thermocline is
common in reservoirs and usually occurs at the depth of 8m to 23m In a study done by
Nyanti (2012) water temperature in Bakun reservoir was reported to undergo thermocline
as depth increased from subsurface to 18m
4
l I
Pusat Khidmat Maldumat Akadfmil UN nsmMALAYSIA SARAWAI~
222 Dissolved Oxygen (DO)
DO is a very essential environmental factor that affects the entire production of a
reservoir and it is also an important indicator of water quality health of reservoir and also
ecological status as it is used for respiration and in biological and chemical reactions
(Mustapha 2008)
DO fluctuate from reservOIr to reservOIr and it is usually affected by
photosynthesis respiration and diel fluctuation In a study done by Ling (2012) it was
reported that the DO is higher at 05m depth at a11 stations in Batang Ai reservoir ranging
from 47 to 87 mgL due to the high phytoplankton photosynthesis rate An example of
diel fluctuation is shown in Kontagora reservoir where the DO is higher during the dry
season than the rainy season (Ibrahim 2009) This shows that the fluctuation also depends
on temperature depth wind and amount of biological activities such as decomposition In
Bakon Dam DO is high at the subsurface but dropped drastically until anoxic level at
depth 2 - 4m 2 years after impoundment and this is mainly due to the decomposition of
organic matter (Nyanti 2012)
223 pH
pH that is suitable for optimal production for inland waters should be about 65 to
85 (Ibrahim 2009) However changes in pH can affect the transfer of nutrients and affect
the condition ofwater quality (Li amp Xu 1995)
Fluctuations in pH can be caused by the photosynthesis process of phytoplanktons
as was reported in Batang Ai reservoir where all pH value was above 7 (Ling 2012)
Carbon dioxide produced by photosynthesis process will alter the pH of water as carbonic
acid will be formed when carbon dioxide reacts with water (Sangpal 2011)
5
Acidic effects in reservoirs can be caused by the transfer of cooler water from other
tributaries where the water is denser and lower in pH Nyanti (2012) reported the pH value
at Bakundam were all acidic ranging from 517-592 and the overall trend of pH in Bakun
dam decreases from upstream towards the dam (Nyanti et aI 2012)
224 Nutrients
Reservoirs are often have higher chances of getting higher element loading
compared to natural lakes as they have greater catchment area and high inflow rates
(Pawar amp Shembekar 2012) The concentration of nutrients varies from reservoir to
reservoir due to the differences in soil and vegetation in the catchment area (Li amp Xu
1995) Nutrients such as nitrates phosphates silicates and iron are important nutrients
required for aquatic growth but may also cause eutrophication and water quality problems
(Li amp Xu 1995) Eutrophication can occur easily in reservoir due to high input of nutrients
into the water and water quality of reservoir will be affected giving rise to unpleasant taste
and odour and affects the dissolution of other gases especially dissolved oxygen
(Mustapha 2008) According to Nyanti (2012) strong rotten egg smell discovered in
Bakun dam indicates high volume of hydrogen sulfide This observation is also supported
by Lourantou (2007) where an irritating odour smell occurs at a reservoir in Belgium
Nutrients input can also be affected by weather and season where nitrate was recorded at
higher values in Ujjani reservoir during post-monsoon season This may be caused by the
oxidation of nitrifying bacteria and biological nitrification Sulphate concentrations in the
dam were very high in both pre and post-monsoon which were probably caused by the
mineral rocks anthropogenically added and also by rain (Sangpal 2011) The phosphate
levels were found to be lower during the pre-monsoon and higher during the postshy
6
monsoon Phosphate leads to eutrophication that can cause unpleasant taste and odour to
the water (Sangpal 2011)
23 Impacts of hydroelectric dams on water quality
Hydroelectric dam has a direct impact to the water quality as it uses the flow rate of
a water course to produce electricity The building of hydroelectric dams has direct impact
towards the chemical thermal and physical parameters of the water body (Bunea 2012)
According to a study done by Bunea (2012) hydroelectric dams have relatively low DO
concentration mostly lower than 50 mglL because of the organic sediments that are left at
the bottom of the reservoir bottom during the initial filing Organic substances left at the
bottom of the reservoir bottom floor will absorb oxygen from the water in order to
decompose producing hydrogen sulphide carbon dioxide and methane (Bunea 2012)
Due to damming for hydroelectric generation water in a reservoir will undergo
stagnation which will lead to thermal stratification (Bunea 2012) According to a study
done by Elci (2008) thermal stratification of the reservoir involves the higher temperature
at the surface and lower temperatures at the bottom which suggests that thermal energy is
very slowly transferred to the bottom layers of the water body Thermal stratification act as
a barrier to re train mixing of the water column This causes an uneven concentration of
nutrients lack of light for photosynthesis at the hypolimnion and the water column may
become anoxic (Elci 2008)
Hydroelectric dams also greatly reduces the water self-purification capacity
According to Wei et al (2009) water self-purification mechanisms are affected by the
physical chemical and biotic processes in a reservoir However dam construction affects
all of the processes as the flow regime water quality and biotic community in the river In
other words dams slow down the river flow capacity block the river continuum and raise
7
water temperature which decreases the water self-purification capacity (Wei et aI 2009)
In a study done in China by Wei et al (2009) it is recorded that the Manwan-Dachaosan
dam has higher ammonia-nitrogen concentration due to the decreased water selfshy
purification capacity as compared to the pre-dam period This suggests that damming has
severely decreased the water self-purification capacity as it blocked the river continuum
8
30 Materials and Methods
31 Study Site
Bakun Hydroelectric Reservoir is a man-made reservoir which is located 60 km
west of Belaga Sarawak Malaysia (Figure 1) The dam was formed after the
impoundment of Balui River The reservoir has a catchment area of 14750 km2 and a total
capacity 43800000 m3 with a surface area of 695 km2 The dam is the second tallest
concrete-faced rockfill dam in the world
Three sampling stations namely stations 1 2 and 3 was selected in the reservoir
Station 1 is at the inundated estuary of the Linau River Station 2 is at the inundated Balui
River and Station 3 is located in the inundated Balui River as well but nearer to the dam
At each station sampling was conducted at 6 levels namely the subsurface 10m 20m
30m 4Om and 50m depths The coordinates of Bakun dam is at longitude 02deg45 23N and
latitude 114deg0347E The coordinates of every sampling station were recorded by the
Global Positioning System (GARMIN GPSMAP 62S) (Table 1) Sampling was carried
out twice the first sampling was from 21 SI August to 27th August 2015 and the second
sampling was 5th November to 11 th November 2015
9
i
EAST MALAYSIA
o
I
-I River I
-I Flooded Area
Station
0 Dam
kill I
Figure 1 Location of the three sampling stations at Bakun Reservoir
Table 1 Coordinates and locations of sampling stations
Station Coordinates Location
N 02deg 39 322 E 114deg 03 295 Estuary of Linau River
2 N 02deg 43 344 E 114deg 01 442 Balui River
3 N 02deg 43 4135 E 114deg 03 340 Further downstream of Balui River
10
32 Water samples
The water samples were taken using Van Dorn water sampler at all three stations
and were taken at 6 different depths which are the subsurface (02m) 10m 20m 30m 40m
and 5Om At each station three replicates of water samples were taken back for laboratory
analysis Water samples were kept in 2 L polyethylene water bottles that has been acid
washed and were stored in cooler box filled with ice All samples were taken to the
laboratory for further analysis
33 Water quality parameters measured in-situ
Temperature dissolved oxygen (DO) pH electrical conductivity total dissolved
solids (TDS) and turbidity were taken using YSI Multiparameter Water Quality 6920 V2
The depths of each station were measured using depth finder Water transparency was also
measured using secchi disc at each station
34 Water quality parameters analysed ex-situ
341 Biochemical oxygen demand in five days (BODs)
BODs were determined by filling water samples into 300 ml BOD bottles DO
readings of the water samples were measured from the bottles All BOD bottles were
wrapped with aluminum foil to prevent light penetration and were kept in a cooler box for
5 days The initial DO value was recorded as DJ and on the 5th day the DO reading was
recorded as Ds The formula that was used for measuring BODs follows the protocol
outlined by APHA (1998)
11
BOD5 (mglL) = DJ - D5
Where DJ = Initial DO of sample immediately after preparation (mglL)
D5 = DO value after 5 days incubation at 25degC (mglL)
342 Total suspended solids (TSS)
Total suspended solids were analyzed using standard method APHA (1998) For
TSS analysis there was pre-fieldtrip sampling method and post-fieldtrip method For preshy
fieldtrip method glass fibre filter paper (GFIC 47 nun diameter 045 Ilm membrane) were
soaked in distilled water Each filter paper is placed on a piece of aluminum foil and was
dried in the oven at 103degC - 105degC overnight Filter paper then was allowed to cool for 10
minutes before weighing it using an analytical balance (ACCULAB ALC - 210) The
initial weight was recorded For post-fieldtrip method the glass fibre paper was placed on
the inter-plate of the filter funnel using a pair of forceps A known volume of water
samples was filtered using a vacuum pump After that filter paper was removed from the
filtration funnel and was placed back into the aluminum foil Filter paper was dried in the
oven at 103degC - 105degC overnight (APHA 1998) Filter paper was then taken out of the
oven and allowed to cool until room temperature before weighing The final reading of the
filtered glass fibre paper was recorded and TSS was calculated using the formula
w -wTSS (mglL) = J I
V
Where W = Initial weight of filter paper
WJ = Final weight of filter paper
V = Volume of water samples filtered (L)
12
4 Chlorophyll-a
The concentration of chlorophyll-a In the water samples were analyzed using
staDdard method APHA (1998) For chlorophyll-a analysis water samples were filtered
using vacuum pump Filter paper containing chlorophyll-a was taken from the vacuum
pump for analysis The samples were grinded by using a grinder and 5 - 6 mL of 90
acetone was added into the mortar Samples were grinded for about 5 minutes and all
materials in the mortar were placed into a capped test tube Ninety percent acetone was
added into the test tube to make up the volume to 10mL Test tube was folded with
aluminum foil and was placed in the refrigerator for 4 - 18 hours to facilitate complete
extraction of the pigments The liquid extracted was transferred into the centrifuge tube
The samples were placed into a centrifuge for about 10 minutes under 3000 rpm Optical
density was determined using spectrophotometer at wavelength of 750 nm 664 run 647
am and 630 nm Each extinctions for small turbidity blank was corrected by subtracting
750 nm from 664 nm and 630 run absorptions
The concentration of chlorophyll-a in the extract of the pigment after correction was
calculated using
Where E = the absorption in the respective wavelength
After determining the concentration of the chlorophyll-a in the extract the amount of
cblorophyll-a in the pigment per unit volume of water filtered was calculated as follows
13
Ca(v)Chlorophyll-a (Jg IL) = - shyv
Where Co = Chlorophyll-a pigment concentration in JgmL
v = Volume ofacetone in mL
v = Volume of samples in L
344 Ammonia-nitrogen (NH3-N)
For ammonia-nitrogen (NH3-N) the concentration was determined using standard
method 8038 Nessler Method (HACH 2000) A 25 mL prepared sample and 25 mL of
deionized water were filled into a separate 25 mL mixing graduated cylinder Three drops
of Mineral Stabilizer were added to both of the cylinders The cylinders were inverted
several times to mix the content After that 1 mL of Nessler reagent was pipetted into both
of the cylinders and the cylinders were inverted several times to mix the content A one-
minute reaction was started Both the solutions were poured into a square sample cell A
yellow colour formation will indicate the presence of ammonia When the timer expired
the blank was inserted into the square sample cell with the fill line facing the right The
reading at 425 run was zeroed The prepared sample was inserted into the cell holder of
Spectrophotometer DR 2800 (HACH 2000) with the fill line facing right and the reading
displayed was recorded
345 Nitrate (NO)-)
For nitrate analysis the concentration was determined using standard method 8192
Cadmium Reduction Method (HACH 2000) The sample was filled until the 15 mL mark
of a 25 mL graduated measuring cylinder The content of one Nitra Ver6 Nitrate Reagent
Pillow Powder was added into the cylinder and capped with a stopper The cylinder was
14
Hence the goal of this study is to obtain detailed information on the physicoshy
chemical water properties of the Bakun Hydroelectric Dam 3 years and 7 months after it
has reached its full supply level Therefore the objectives of this study were
(i) To determine the water quality at six depths at three stations in the
reservOIr
(ii) Compare the characteristics of the water quality among the depths and
stations and
(iii) Determine the changes in water quality characteristics 5 years 6 months
after the dam was impounded
2
jl - - I
20 Literature Review
21 Reservoir
According to Pawar amp Shembekar (2012) water is important and it is the most
abundant resource in the world which man has used for decades Water covers about 70
of the earths surface but only 27 of the total amount is freshwater of which 1 is iceshy
free water in the rivers lakes and atmosphere as biological water It is believed that only
0001 92 of the total water on earth is available for human use (Pawar amp Shembekar
2012) Hence reservoirs are created in order to provide domestic water supply generation
of electricity and aquaculture In Malaysia 63 large reservoirs with a total storage of 25
billion m3 have been constructed (Makhlough 2008)
Water quality in reservoirs is greatly affected by the composition of plant materials
that were submerged during the inundation process In a study done by Ling (2012) water
in the Batang Ai reservoir contains high sulfide concentrations especially at inundated
areas Besides that Nyanti (2012) also reported that the anoxic condition and the acidic
condition in Bakun Dam is due to the decomposition of submerged carbonaceous
materials
Additionally human activities in and around reservoirs and the physical and
chemical properties of water will be affected (Mustapha 2008) Precipitation evaporation
and ground movement can also affect water quality In Batang Ai reservoir the dissolved
oxygen was reported to be lower due to nearby cage aquaculture as it is consumed by
microorganisms in the decomposition of organic matter (Ling 2012)
22 Water quality
Water quality in a reservoir is the physical and chemical limnology of a reservoir
(Sidnei 1992) and includes all physical chemical and biological aspects of water that
3
influence the beneficial usage of water (Mustapha 2008) In reservoirs water quality
deterioration usually comes from excessive nutrient inputs eutrophication acidification
heavy metal contamination organic pollution and obnoxious fishing practices (Mustapha
2008)
Therefore water quality is an important indicator of the ecological status of a
reservoir It is reported that the significant lower dissolved oxygen is recorded due to
higher turbidity and increased suspended solids which affect the dissolution of oxygen
which is brought in by the flood that occurred in Oyun Reservoir (Mustapha 2008)
Additionally in a study done at Bakun Dam turbidity is affected by the suspended solids
from eroded soils from the logging activities in the watershed upstream from the north of
the reservoir (Nyanti 2012)
221 Temperature
Temperature is very important to a reservoir as it affects chemical and biological
activities of aquatic organisms (Sangpal 2011) In a reservoir when the upper layer and
the lower layer have great variation in temperature thermocline will occur Thermal
stratification in deep reservoir is an important natural process which gives significant
effects on water quality The production of ammonia sulphide and algal nutrients are
dependent on the changes in water temperature which subsequently affects the water
quality (Baharim 2011) Besides that vertical distribution and change in water
temperature can affect productivity of the natural organisms in the reservoirs However
the effect varies from reservoir to reservoir According to Li amp Xu (1995) thermocline is
common in reservoirs and usually occurs at the depth of 8m to 23m In a study done by
Nyanti (2012) water temperature in Bakun reservoir was reported to undergo thermocline
as depth increased from subsurface to 18m
4
l I
Pusat Khidmat Maldumat Akadfmil UN nsmMALAYSIA SARAWAI~
222 Dissolved Oxygen (DO)
DO is a very essential environmental factor that affects the entire production of a
reservoir and it is also an important indicator of water quality health of reservoir and also
ecological status as it is used for respiration and in biological and chemical reactions
(Mustapha 2008)
DO fluctuate from reservOIr to reservOIr and it is usually affected by
photosynthesis respiration and diel fluctuation In a study done by Ling (2012) it was
reported that the DO is higher at 05m depth at a11 stations in Batang Ai reservoir ranging
from 47 to 87 mgL due to the high phytoplankton photosynthesis rate An example of
diel fluctuation is shown in Kontagora reservoir where the DO is higher during the dry
season than the rainy season (Ibrahim 2009) This shows that the fluctuation also depends
on temperature depth wind and amount of biological activities such as decomposition In
Bakon Dam DO is high at the subsurface but dropped drastically until anoxic level at
depth 2 - 4m 2 years after impoundment and this is mainly due to the decomposition of
organic matter (Nyanti 2012)
223 pH
pH that is suitable for optimal production for inland waters should be about 65 to
85 (Ibrahim 2009) However changes in pH can affect the transfer of nutrients and affect
the condition ofwater quality (Li amp Xu 1995)
Fluctuations in pH can be caused by the photosynthesis process of phytoplanktons
as was reported in Batang Ai reservoir where all pH value was above 7 (Ling 2012)
Carbon dioxide produced by photosynthesis process will alter the pH of water as carbonic
acid will be formed when carbon dioxide reacts with water (Sangpal 2011)
5
Acidic effects in reservoirs can be caused by the transfer of cooler water from other
tributaries where the water is denser and lower in pH Nyanti (2012) reported the pH value
at Bakundam were all acidic ranging from 517-592 and the overall trend of pH in Bakun
dam decreases from upstream towards the dam (Nyanti et aI 2012)
224 Nutrients
Reservoirs are often have higher chances of getting higher element loading
compared to natural lakes as they have greater catchment area and high inflow rates
(Pawar amp Shembekar 2012) The concentration of nutrients varies from reservoir to
reservoir due to the differences in soil and vegetation in the catchment area (Li amp Xu
1995) Nutrients such as nitrates phosphates silicates and iron are important nutrients
required for aquatic growth but may also cause eutrophication and water quality problems
(Li amp Xu 1995) Eutrophication can occur easily in reservoir due to high input of nutrients
into the water and water quality of reservoir will be affected giving rise to unpleasant taste
and odour and affects the dissolution of other gases especially dissolved oxygen
(Mustapha 2008) According to Nyanti (2012) strong rotten egg smell discovered in
Bakun dam indicates high volume of hydrogen sulfide This observation is also supported
by Lourantou (2007) where an irritating odour smell occurs at a reservoir in Belgium
Nutrients input can also be affected by weather and season where nitrate was recorded at
higher values in Ujjani reservoir during post-monsoon season This may be caused by the
oxidation of nitrifying bacteria and biological nitrification Sulphate concentrations in the
dam were very high in both pre and post-monsoon which were probably caused by the
mineral rocks anthropogenically added and also by rain (Sangpal 2011) The phosphate
levels were found to be lower during the pre-monsoon and higher during the postshy
6
monsoon Phosphate leads to eutrophication that can cause unpleasant taste and odour to
the water (Sangpal 2011)
23 Impacts of hydroelectric dams on water quality
Hydroelectric dam has a direct impact to the water quality as it uses the flow rate of
a water course to produce electricity The building of hydroelectric dams has direct impact
towards the chemical thermal and physical parameters of the water body (Bunea 2012)
According to a study done by Bunea (2012) hydroelectric dams have relatively low DO
concentration mostly lower than 50 mglL because of the organic sediments that are left at
the bottom of the reservoir bottom during the initial filing Organic substances left at the
bottom of the reservoir bottom floor will absorb oxygen from the water in order to
decompose producing hydrogen sulphide carbon dioxide and methane (Bunea 2012)
Due to damming for hydroelectric generation water in a reservoir will undergo
stagnation which will lead to thermal stratification (Bunea 2012) According to a study
done by Elci (2008) thermal stratification of the reservoir involves the higher temperature
at the surface and lower temperatures at the bottom which suggests that thermal energy is
very slowly transferred to the bottom layers of the water body Thermal stratification act as
a barrier to re train mixing of the water column This causes an uneven concentration of
nutrients lack of light for photosynthesis at the hypolimnion and the water column may
become anoxic (Elci 2008)
Hydroelectric dams also greatly reduces the water self-purification capacity
According to Wei et al (2009) water self-purification mechanisms are affected by the
physical chemical and biotic processes in a reservoir However dam construction affects
all of the processes as the flow regime water quality and biotic community in the river In
other words dams slow down the river flow capacity block the river continuum and raise
7
water temperature which decreases the water self-purification capacity (Wei et aI 2009)
In a study done in China by Wei et al (2009) it is recorded that the Manwan-Dachaosan
dam has higher ammonia-nitrogen concentration due to the decreased water selfshy
purification capacity as compared to the pre-dam period This suggests that damming has
severely decreased the water self-purification capacity as it blocked the river continuum
8
30 Materials and Methods
31 Study Site
Bakun Hydroelectric Reservoir is a man-made reservoir which is located 60 km
west of Belaga Sarawak Malaysia (Figure 1) The dam was formed after the
impoundment of Balui River The reservoir has a catchment area of 14750 km2 and a total
capacity 43800000 m3 with a surface area of 695 km2 The dam is the second tallest
concrete-faced rockfill dam in the world
Three sampling stations namely stations 1 2 and 3 was selected in the reservoir
Station 1 is at the inundated estuary of the Linau River Station 2 is at the inundated Balui
River and Station 3 is located in the inundated Balui River as well but nearer to the dam
At each station sampling was conducted at 6 levels namely the subsurface 10m 20m
30m 4Om and 50m depths The coordinates of Bakun dam is at longitude 02deg45 23N and
latitude 114deg0347E The coordinates of every sampling station were recorded by the
Global Positioning System (GARMIN GPSMAP 62S) (Table 1) Sampling was carried
out twice the first sampling was from 21 SI August to 27th August 2015 and the second
sampling was 5th November to 11 th November 2015
9
i
EAST MALAYSIA
o
I
-I River I
-I Flooded Area
Station
0 Dam
kill I
Figure 1 Location of the three sampling stations at Bakun Reservoir
Table 1 Coordinates and locations of sampling stations
Station Coordinates Location
N 02deg 39 322 E 114deg 03 295 Estuary of Linau River
2 N 02deg 43 344 E 114deg 01 442 Balui River
3 N 02deg 43 4135 E 114deg 03 340 Further downstream of Balui River
10
32 Water samples
The water samples were taken using Van Dorn water sampler at all three stations
and were taken at 6 different depths which are the subsurface (02m) 10m 20m 30m 40m
and 5Om At each station three replicates of water samples were taken back for laboratory
analysis Water samples were kept in 2 L polyethylene water bottles that has been acid
washed and were stored in cooler box filled with ice All samples were taken to the
laboratory for further analysis
33 Water quality parameters measured in-situ
Temperature dissolved oxygen (DO) pH electrical conductivity total dissolved
solids (TDS) and turbidity were taken using YSI Multiparameter Water Quality 6920 V2
The depths of each station were measured using depth finder Water transparency was also
measured using secchi disc at each station
34 Water quality parameters analysed ex-situ
341 Biochemical oxygen demand in five days (BODs)
BODs were determined by filling water samples into 300 ml BOD bottles DO
readings of the water samples were measured from the bottles All BOD bottles were
wrapped with aluminum foil to prevent light penetration and were kept in a cooler box for
5 days The initial DO value was recorded as DJ and on the 5th day the DO reading was
recorded as Ds The formula that was used for measuring BODs follows the protocol
outlined by APHA (1998)
11
BOD5 (mglL) = DJ - D5
Where DJ = Initial DO of sample immediately after preparation (mglL)
D5 = DO value after 5 days incubation at 25degC (mglL)
342 Total suspended solids (TSS)
Total suspended solids were analyzed using standard method APHA (1998) For
TSS analysis there was pre-fieldtrip sampling method and post-fieldtrip method For preshy
fieldtrip method glass fibre filter paper (GFIC 47 nun diameter 045 Ilm membrane) were
soaked in distilled water Each filter paper is placed on a piece of aluminum foil and was
dried in the oven at 103degC - 105degC overnight Filter paper then was allowed to cool for 10
minutes before weighing it using an analytical balance (ACCULAB ALC - 210) The
initial weight was recorded For post-fieldtrip method the glass fibre paper was placed on
the inter-plate of the filter funnel using a pair of forceps A known volume of water
samples was filtered using a vacuum pump After that filter paper was removed from the
filtration funnel and was placed back into the aluminum foil Filter paper was dried in the
oven at 103degC - 105degC overnight (APHA 1998) Filter paper was then taken out of the
oven and allowed to cool until room temperature before weighing The final reading of the
filtered glass fibre paper was recorded and TSS was calculated using the formula
w -wTSS (mglL) = J I
V
Where W = Initial weight of filter paper
WJ = Final weight of filter paper
V = Volume of water samples filtered (L)
12
4 Chlorophyll-a
The concentration of chlorophyll-a In the water samples were analyzed using
staDdard method APHA (1998) For chlorophyll-a analysis water samples were filtered
using vacuum pump Filter paper containing chlorophyll-a was taken from the vacuum
pump for analysis The samples were grinded by using a grinder and 5 - 6 mL of 90
acetone was added into the mortar Samples were grinded for about 5 minutes and all
materials in the mortar were placed into a capped test tube Ninety percent acetone was
added into the test tube to make up the volume to 10mL Test tube was folded with
aluminum foil and was placed in the refrigerator for 4 - 18 hours to facilitate complete
extraction of the pigments The liquid extracted was transferred into the centrifuge tube
The samples were placed into a centrifuge for about 10 minutes under 3000 rpm Optical
density was determined using spectrophotometer at wavelength of 750 nm 664 run 647
am and 630 nm Each extinctions for small turbidity blank was corrected by subtracting
750 nm from 664 nm and 630 run absorptions
The concentration of chlorophyll-a in the extract of the pigment after correction was
calculated using
Where E = the absorption in the respective wavelength
After determining the concentration of the chlorophyll-a in the extract the amount of
cblorophyll-a in the pigment per unit volume of water filtered was calculated as follows
13
Ca(v)Chlorophyll-a (Jg IL) = - shyv
Where Co = Chlorophyll-a pigment concentration in JgmL
v = Volume ofacetone in mL
v = Volume of samples in L
344 Ammonia-nitrogen (NH3-N)
For ammonia-nitrogen (NH3-N) the concentration was determined using standard
method 8038 Nessler Method (HACH 2000) A 25 mL prepared sample and 25 mL of
deionized water were filled into a separate 25 mL mixing graduated cylinder Three drops
of Mineral Stabilizer were added to both of the cylinders The cylinders were inverted
several times to mix the content After that 1 mL of Nessler reagent was pipetted into both
of the cylinders and the cylinders were inverted several times to mix the content A one-
minute reaction was started Both the solutions were poured into a square sample cell A
yellow colour formation will indicate the presence of ammonia When the timer expired
the blank was inserted into the square sample cell with the fill line facing the right The
reading at 425 run was zeroed The prepared sample was inserted into the cell holder of
Spectrophotometer DR 2800 (HACH 2000) with the fill line facing right and the reading
displayed was recorded
345 Nitrate (NO)-)
For nitrate analysis the concentration was determined using standard method 8192
Cadmium Reduction Method (HACH 2000) The sample was filled until the 15 mL mark
of a 25 mL graduated measuring cylinder The content of one Nitra Ver6 Nitrate Reagent
Pillow Powder was added into the cylinder and capped with a stopper The cylinder was
14
20 Literature Review
21 Reservoir
According to Pawar amp Shembekar (2012) water is important and it is the most
abundant resource in the world which man has used for decades Water covers about 70
of the earths surface but only 27 of the total amount is freshwater of which 1 is iceshy
free water in the rivers lakes and atmosphere as biological water It is believed that only
0001 92 of the total water on earth is available for human use (Pawar amp Shembekar
2012) Hence reservoirs are created in order to provide domestic water supply generation
of electricity and aquaculture In Malaysia 63 large reservoirs with a total storage of 25
billion m3 have been constructed (Makhlough 2008)
Water quality in reservoirs is greatly affected by the composition of plant materials
that were submerged during the inundation process In a study done by Ling (2012) water
in the Batang Ai reservoir contains high sulfide concentrations especially at inundated
areas Besides that Nyanti (2012) also reported that the anoxic condition and the acidic
condition in Bakun Dam is due to the decomposition of submerged carbonaceous
materials
Additionally human activities in and around reservoirs and the physical and
chemical properties of water will be affected (Mustapha 2008) Precipitation evaporation
and ground movement can also affect water quality In Batang Ai reservoir the dissolved
oxygen was reported to be lower due to nearby cage aquaculture as it is consumed by
microorganisms in the decomposition of organic matter (Ling 2012)
22 Water quality
Water quality in a reservoir is the physical and chemical limnology of a reservoir
(Sidnei 1992) and includes all physical chemical and biological aspects of water that
3
influence the beneficial usage of water (Mustapha 2008) In reservoirs water quality
deterioration usually comes from excessive nutrient inputs eutrophication acidification
heavy metal contamination organic pollution and obnoxious fishing practices (Mustapha
2008)
Therefore water quality is an important indicator of the ecological status of a
reservoir It is reported that the significant lower dissolved oxygen is recorded due to
higher turbidity and increased suspended solids which affect the dissolution of oxygen
which is brought in by the flood that occurred in Oyun Reservoir (Mustapha 2008)
Additionally in a study done at Bakun Dam turbidity is affected by the suspended solids
from eroded soils from the logging activities in the watershed upstream from the north of
the reservoir (Nyanti 2012)
221 Temperature
Temperature is very important to a reservoir as it affects chemical and biological
activities of aquatic organisms (Sangpal 2011) In a reservoir when the upper layer and
the lower layer have great variation in temperature thermocline will occur Thermal
stratification in deep reservoir is an important natural process which gives significant
effects on water quality The production of ammonia sulphide and algal nutrients are
dependent on the changes in water temperature which subsequently affects the water
quality (Baharim 2011) Besides that vertical distribution and change in water
temperature can affect productivity of the natural organisms in the reservoirs However
the effect varies from reservoir to reservoir According to Li amp Xu (1995) thermocline is
common in reservoirs and usually occurs at the depth of 8m to 23m In a study done by
Nyanti (2012) water temperature in Bakun reservoir was reported to undergo thermocline
as depth increased from subsurface to 18m
4
l I
Pusat Khidmat Maldumat Akadfmil UN nsmMALAYSIA SARAWAI~
222 Dissolved Oxygen (DO)
DO is a very essential environmental factor that affects the entire production of a
reservoir and it is also an important indicator of water quality health of reservoir and also
ecological status as it is used for respiration and in biological and chemical reactions
(Mustapha 2008)
DO fluctuate from reservOIr to reservOIr and it is usually affected by
photosynthesis respiration and diel fluctuation In a study done by Ling (2012) it was
reported that the DO is higher at 05m depth at a11 stations in Batang Ai reservoir ranging
from 47 to 87 mgL due to the high phytoplankton photosynthesis rate An example of
diel fluctuation is shown in Kontagora reservoir where the DO is higher during the dry
season than the rainy season (Ibrahim 2009) This shows that the fluctuation also depends
on temperature depth wind and amount of biological activities such as decomposition In
Bakon Dam DO is high at the subsurface but dropped drastically until anoxic level at
depth 2 - 4m 2 years after impoundment and this is mainly due to the decomposition of
organic matter (Nyanti 2012)
223 pH
pH that is suitable for optimal production for inland waters should be about 65 to
85 (Ibrahim 2009) However changes in pH can affect the transfer of nutrients and affect
the condition ofwater quality (Li amp Xu 1995)
Fluctuations in pH can be caused by the photosynthesis process of phytoplanktons
as was reported in Batang Ai reservoir where all pH value was above 7 (Ling 2012)
Carbon dioxide produced by photosynthesis process will alter the pH of water as carbonic
acid will be formed when carbon dioxide reacts with water (Sangpal 2011)
5
Acidic effects in reservoirs can be caused by the transfer of cooler water from other
tributaries where the water is denser and lower in pH Nyanti (2012) reported the pH value
at Bakundam were all acidic ranging from 517-592 and the overall trend of pH in Bakun
dam decreases from upstream towards the dam (Nyanti et aI 2012)
224 Nutrients
Reservoirs are often have higher chances of getting higher element loading
compared to natural lakes as they have greater catchment area and high inflow rates
(Pawar amp Shembekar 2012) The concentration of nutrients varies from reservoir to
reservoir due to the differences in soil and vegetation in the catchment area (Li amp Xu
1995) Nutrients such as nitrates phosphates silicates and iron are important nutrients
required for aquatic growth but may also cause eutrophication and water quality problems
(Li amp Xu 1995) Eutrophication can occur easily in reservoir due to high input of nutrients
into the water and water quality of reservoir will be affected giving rise to unpleasant taste
and odour and affects the dissolution of other gases especially dissolved oxygen
(Mustapha 2008) According to Nyanti (2012) strong rotten egg smell discovered in
Bakun dam indicates high volume of hydrogen sulfide This observation is also supported
by Lourantou (2007) where an irritating odour smell occurs at a reservoir in Belgium
Nutrients input can also be affected by weather and season where nitrate was recorded at
higher values in Ujjani reservoir during post-monsoon season This may be caused by the
oxidation of nitrifying bacteria and biological nitrification Sulphate concentrations in the
dam were very high in both pre and post-monsoon which were probably caused by the
mineral rocks anthropogenically added and also by rain (Sangpal 2011) The phosphate
levels were found to be lower during the pre-monsoon and higher during the postshy
6
monsoon Phosphate leads to eutrophication that can cause unpleasant taste and odour to
the water (Sangpal 2011)
23 Impacts of hydroelectric dams on water quality
Hydroelectric dam has a direct impact to the water quality as it uses the flow rate of
a water course to produce electricity The building of hydroelectric dams has direct impact
towards the chemical thermal and physical parameters of the water body (Bunea 2012)
According to a study done by Bunea (2012) hydroelectric dams have relatively low DO
concentration mostly lower than 50 mglL because of the organic sediments that are left at
the bottom of the reservoir bottom during the initial filing Organic substances left at the
bottom of the reservoir bottom floor will absorb oxygen from the water in order to
decompose producing hydrogen sulphide carbon dioxide and methane (Bunea 2012)
Due to damming for hydroelectric generation water in a reservoir will undergo
stagnation which will lead to thermal stratification (Bunea 2012) According to a study
done by Elci (2008) thermal stratification of the reservoir involves the higher temperature
at the surface and lower temperatures at the bottom which suggests that thermal energy is
very slowly transferred to the bottom layers of the water body Thermal stratification act as
a barrier to re train mixing of the water column This causes an uneven concentration of
nutrients lack of light for photosynthesis at the hypolimnion and the water column may
become anoxic (Elci 2008)
Hydroelectric dams also greatly reduces the water self-purification capacity
According to Wei et al (2009) water self-purification mechanisms are affected by the
physical chemical and biotic processes in a reservoir However dam construction affects
all of the processes as the flow regime water quality and biotic community in the river In
other words dams slow down the river flow capacity block the river continuum and raise
7
water temperature which decreases the water self-purification capacity (Wei et aI 2009)
In a study done in China by Wei et al (2009) it is recorded that the Manwan-Dachaosan
dam has higher ammonia-nitrogen concentration due to the decreased water selfshy
purification capacity as compared to the pre-dam period This suggests that damming has
severely decreased the water self-purification capacity as it blocked the river continuum
8
30 Materials and Methods
31 Study Site
Bakun Hydroelectric Reservoir is a man-made reservoir which is located 60 km
west of Belaga Sarawak Malaysia (Figure 1) The dam was formed after the
impoundment of Balui River The reservoir has a catchment area of 14750 km2 and a total
capacity 43800000 m3 with a surface area of 695 km2 The dam is the second tallest
concrete-faced rockfill dam in the world
Three sampling stations namely stations 1 2 and 3 was selected in the reservoir
Station 1 is at the inundated estuary of the Linau River Station 2 is at the inundated Balui
River and Station 3 is located in the inundated Balui River as well but nearer to the dam
At each station sampling was conducted at 6 levels namely the subsurface 10m 20m
30m 4Om and 50m depths The coordinates of Bakun dam is at longitude 02deg45 23N and
latitude 114deg0347E The coordinates of every sampling station were recorded by the
Global Positioning System (GARMIN GPSMAP 62S) (Table 1) Sampling was carried
out twice the first sampling was from 21 SI August to 27th August 2015 and the second
sampling was 5th November to 11 th November 2015
9
i
EAST MALAYSIA
o
I
-I River I
-I Flooded Area
Station
0 Dam
kill I
Figure 1 Location of the three sampling stations at Bakun Reservoir
Table 1 Coordinates and locations of sampling stations
Station Coordinates Location
N 02deg 39 322 E 114deg 03 295 Estuary of Linau River
2 N 02deg 43 344 E 114deg 01 442 Balui River
3 N 02deg 43 4135 E 114deg 03 340 Further downstream of Balui River
10
32 Water samples
The water samples were taken using Van Dorn water sampler at all three stations
and were taken at 6 different depths which are the subsurface (02m) 10m 20m 30m 40m
and 5Om At each station three replicates of water samples were taken back for laboratory
analysis Water samples were kept in 2 L polyethylene water bottles that has been acid
washed and were stored in cooler box filled with ice All samples were taken to the
laboratory for further analysis
33 Water quality parameters measured in-situ
Temperature dissolved oxygen (DO) pH electrical conductivity total dissolved
solids (TDS) and turbidity were taken using YSI Multiparameter Water Quality 6920 V2
The depths of each station were measured using depth finder Water transparency was also
measured using secchi disc at each station
34 Water quality parameters analysed ex-situ
341 Biochemical oxygen demand in five days (BODs)
BODs were determined by filling water samples into 300 ml BOD bottles DO
readings of the water samples were measured from the bottles All BOD bottles were
wrapped with aluminum foil to prevent light penetration and were kept in a cooler box for
5 days The initial DO value was recorded as DJ and on the 5th day the DO reading was
recorded as Ds The formula that was used for measuring BODs follows the protocol
outlined by APHA (1998)
11
BOD5 (mglL) = DJ - D5
Where DJ = Initial DO of sample immediately after preparation (mglL)
D5 = DO value after 5 days incubation at 25degC (mglL)
342 Total suspended solids (TSS)
Total suspended solids were analyzed using standard method APHA (1998) For
TSS analysis there was pre-fieldtrip sampling method and post-fieldtrip method For preshy
fieldtrip method glass fibre filter paper (GFIC 47 nun diameter 045 Ilm membrane) were
soaked in distilled water Each filter paper is placed on a piece of aluminum foil and was
dried in the oven at 103degC - 105degC overnight Filter paper then was allowed to cool for 10
minutes before weighing it using an analytical balance (ACCULAB ALC - 210) The
initial weight was recorded For post-fieldtrip method the glass fibre paper was placed on
the inter-plate of the filter funnel using a pair of forceps A known volume of water
samples was filtered using a vacuum pump After that filter paper was removed from the
filtration funnel and was placed back into the aluminum foil Filter paper was dried in the
oven at 103degC - 105degC overnight (APHA 1998) Filter paper was then taken out of the
oven and allowed to cool until room temperature before weighing The final reading of the
filtered glass fibre paper was recorded and TSS was calculated using the formula
w -wTSS (mglL) = J I
V
Where W = Initial weight of filter paper
WJ = Final weight of filter paper
V = Volume of water samples filtered (L)
12
4 Chlorophyll-a
The concentration of chlorophyll-a In the water samples were analyzed using
staDdard method APHA (1998) For chlorophyll-a analysis water samples were filtered
using vacuum pump Filter paper containing chlorophyll-a was taken from the vacuum
pump for analysis The samples were grinded by using a grinder and 5 - 6 mL of 90
acetone was added into the mortar Samples were grinded for about 5 minutes and all
materials in the mortar were placed into a capped test tube Ninety percent acetone was
added into the test tube to make up the volume to 10mL Test tube was folded with
aluminum foil and was placed in the refrigerator for 4 - 18 hours to facilitate complete
extraction of the pigments The liquid extracted was transferred into the centrifuge tube
The samples were placed into a centrifuge for about 10 minutes under 3000 rpm Optical
density was determined using spectrophotometer at wavelength of 750 nm 664 run 647
am and 630 nm Each extinctions for small turbidity blank was corrected by subtracting
750 nm from 664 nm and 630 run absorptions
The concentration of chlorophyll-a in the extract of the pigment after correction was
calculated using
Where E = the absorption in the respective wavelength
After determining the concentration of the chlorophyll-a in the extract the amount of
cblorophyll-a in the pigment per unit volume of water filtered was calculated as follows
13
Ca(v)Chlorophyll-a (Jg IL) = - shyv
Where Co = Chlorophyll-a pigment concentration in JgmL
v = Volume ofacetone in mL
v = Volume of samples in L
344 Ammonia-nitrogen (NH3-N)
For ammonia-nitrogen (NH3-N) the concentration was determined using standard
method 8038 Nessler Method (HACH 2000) A 25 mL prepared sample and 25 mL of
deionized water were filled into a separate 25 mL mixing graduated cylinder Three drops
of Mineral Stabilizer were added to both of the cylinders The cylinders were inverted
several times to mix the content After that 1 mL of Nessler reagent was pipetted into both
of the cylinders and the cylinders were inverted several times to mix the content A one-
minute reaction was started Both the solutions were poured into a square sample cell A
yellow colour formation will indicate the presence of ammonia When the timer expired
the blank was inserted into the square sample cell with the fill line facing the right The
reading at 425 run was zeroed The prepared sample was inserted into the cell holder of
Spectrophotometer DR 2800 (HACH 2000) with the fill line facing right and the reading
displayed was recorded
345 Nitrate (NO)-)
For nitrate analysis the concentration was determined using standard method 8192
Cadmium Reduction Method (HACH 2000) The sample was filled until the 15 mL mark
of a 25 mL graduated measuring cylinder The content of one Nitra Ver6 Nitrate Reagent
Pillow Powder was added into the cylinder and capped with a stopper The cylinder was
14
influence the beneficial usage of water (Mustapha 2008) In reservoirs water quality
deterioration usually comes from excessive nutrient inputs eutrophication acidification
heavy metal contamination organic pollution and obnoxious fishing practices (Mustapha
2008)
Therefore water quality is an important indicator of the ecological status of a
reservoir It is reported that the significant lower dissolved oxygen is recorded due to
higher turbidity and increased suspended solids which affect the dissolution of oxygen
which is brought in by the flood that occurred in Oyun Reservoir (Mustapha 2008)
Additionally in a study done at Bakun Dam turbidity is affected by the suspended solids
from eroded soils from the logging activities in the watershed upstream from the north of
the reservoir (Nyanti 2012)
221 Temperature
Temperature is very important to a reservoir as it affects chemical and biological
activities of aquatic organisms (Sangpal 2011) In a reservoir when the upper layer and
the lower layer have great variation in temperature thermocline will occur Thermal
stratification in deep reservoir is an important natural process which gives significant
effects on water quality The production of ammonia sulphide and algal nutrients are
dependent on the changes in water temperature which subsequently affects the water
quality (Baharim 2011) Besides that vertical distribution and change in water
temperature can affect productivity of the natural organisms in the reservoirs However
the effect varies from reservoir to reservoir According to Li amp Xu (1995) thermocline is
common in reservoirs and usually occurs at the depth of 8m to 23m In a study done by
Nyanti (2012) water temperature in Bakun reservoir was reported to undergo thermocline
as depth increased from subsurface to 18m
4
l I
Pusat Khidmat Maldumat Akadfmil UN nsmMALAYSIA SARAWAI~
222 Dissolved Oxygen (DO)
DO is a very essential environmental factor that affects the entire production of a
reservoir and it is also an important indicator of water quality health of reservoir and also
ecological status as it is used for respiration and in biological and chemical reactions
(Mustapha 2008)
DO fluctuate from reservOIr to reservOIr and it is usually affected by
photosynthesis respiration and diel fluctuation In a study done by Ling (2012) it was
reported that the DO is higher at 05m depth at a11 stations in Batang Ai reservoir ranging
from 47 to 87 mgL due to the high phytoplankton photosynthesis rate An example of
diel fluctuation is shown in Kontagora reservoir where the DO is higher during the dry
season than the rainy season (Ibrahim 2009) This shows that the fluctuation also depends
on temperature depth wind and amount of biological activities such as decomposition In
Bakon Dam DO is high at the subsurface but dropped drastically until anoxic level at
depth 2 - 4m 2 years after impoundment and this is mainly due to the decomposition of
organic matter (Nyanti 2012)
223 pH
pH that is suitable for optimal production for inland waters should be about 65 to
85 (Ibrahim 2009) However changes in pH can affect the transfer of nutrients and affect
the condition ofwater quality (Li amp Xu 1995)
Fluctuations in pH can be caused by the photosynthesis process of phytoplanktons
as was reported in Batang Ai reservoir where all pH value was above 7 (Ling 2012)
Carbon dioxide produced by photosynthesis process will alter the pH of water as carbonic
acid will be formed when carbon dioxide reacts with water (Sangpal 2011)
5
Acidic effects in reservoirs can be caused by the transfer of cooler water from other
tributaries where the water is denser and lower in pH Nyanti (2012) reported the pH value
at Bakundam were all acidic ranging from 517-592 and the overall trend of pH in Bakun
dam decreases from upstream towards the dam (Nyanti et aI 2012)
224 Nutrients
Reservoirs are often have higher chances of getting higher element loading
compared to natural lakes as they have greater catchment area and high inflow rates
(Pawar amp Shembekar 2012) The concentration of nutrients varies from reservoir to
reservoir due to the differences in soil and vegetation in the catchment area (Li amp Xu
1995) Nutrients such as nitrates phosphates silicates and iron are important nutrients
required for aquatic growth but may also cause eutrophication and water quality problems
(Li amp Xu 1995) Eutrophication can occur easily in reservoir due to high input of nutrients
into the water and water quality of reservoir will be affected giving rise to unpleasant taste
and odour and affects the dissolution of other gases especially dissolved oxygen
(Mustapha 2008) According to Nyanti (2012) strong rotten egg smell discovered in
Bakun dam indicates high volume of hydrogen sulfide This observation is also supported
by Lourantou (2007) where an irritating odour smell occurs at a reservoir in Belgium
Nutrients input can also be affected by weather and season where nitrate was recorded at
higher values in Ujjani reservoir during post-monsoon season This may be caused by the
oxidation of nitrifying bacteria and biological nitrification Sulphate concentrations in the
dam were very high in both pre and post-monsoon which were probably caused by the
mineral rocks anthropogenically added and also by rain (Sangpal 2011) The phosphate
levels were found to be lower during the pre-monsoon and higher during the postshy
6
monsoon Phosphate leads to eutrophication that can cause unpleasant taste and odour to
the water (Sangpal 2011)
23 Impacts of hydroelectric dams on water quality
Hydroelectric dam has a direct impact to the water quality as it uses the flow rate of
a water course to produce electricity The building of hydroelectric dams has direct impact
towards the chemical thermal and physical parameters of the water body (Bunea 2012)
According to a study done by Bunea (2012) hydroelectric dams have relatively low DO
concentration mostly lower than 50 mglL because of the organic sediments that are left at
the bottom of the reservoir bottom during the initial filing Organic substances left at the
bottom of the reservoir bottom floor will absorb oxygen from the water in order to
decompose producing hydrogen sulphide carbon dioxide and methane (Bunea 2012)
Due to damming for hydroelectric generation water in a reservoir will undergo
stagnation which will lead to thermal stratification (Bunea 2012) According to a study
done by Elci (2008) thermal stratification of the reservoir involves the higher temperature
at the surface and lower temperatures at the bottom which suggests that thermal energy is
very slowly transferred to the bottom layers of the water body Thermal stratification act as
a barrier to re train mixing of the water column This causes an uneven concentration of
nutrients lack of light for photosynthesis at the hypolimnion and the water column may
become anoxic (Elci 2008)
Hydroelectric dams also greatly reduces the water self-purification capacity
According to Wei et al (2009) water self-purification mechanisms are affected by the
physical chemical and biotic processes in a reservoir However dam construction affects
all of the processes as the flow regime water quality and biotic community in the river In
other words dams slow down the river flow capacity block the river continuum and raise
7
water temperature which decreases the water self-purification capacity (Wei et aI 2009)
In a study done in China by Wei et al (2009) it is recorded that the Manwan-Dachaosan
dam has higher ammonia-nitrogen concentration due to the decreased water selfshy
purification capacity as compared to the pre-dam period This suggests that damming has
severely decreased the water self-purification capacity as it blocked the river continuum
8
30 Materials and Methods
31 Study Site
Bakun Hydroelectric Reservoir is a man-made reservoir which is located 60 km
west of Belaga Sarawak Malaysia (Figure 1) The dam was formed after the
impoundment of Balui River The reservoir has a catchment area of 14750 km2 and a total
capacity 43800000 m3 with a surface area of 695 km2 The dam is the second tallest
concrete-faced rockfill dam in the world
Three sampling stations namely stations 1 2 and 3 was selected in the reservoir
Station 1 is at the inundated estuary of the Linau River Station 2 is at the inundated Balui
River and Station 3 is located in the inundated Balui River as well but nearer to the dam
At each station sampling was conducted at 6 levels namely the subsurface 10m 20m
30m 4Om and 50m depths The coordinates of Bakun dam is at longitude 02deg45 23N and
latitude 114deg0347E The coordinates of every sampling station were recorded by the
Global Positioning System (GARMIN GPSMAP 62S) (Table 1) Sampling was carried
out twice the first sampling was from 21 SI August to 27th August 2015 and the second
sampling was 5th November to 11 th November 2015
9
i
EAST MALAYSIA
o
I
-I River I
-I Flooded Area
Station
0 Dam
kill I
Figure 1 Location of the three sampling stations at Bakun Reservoir
Table 1 Coordinates and locations of sampling stations
Station Coordinates Location
N 02deg 39 322 E 114deg 03 295 Estuary of Linau River
2 N 02deg 43 344 E 114deg 01 442 Balui River
3 N 02deg 43 4135 E 114deg 03 340 Further downstream of Balui River
10
32 Water samples
The water samples were taken using Van Dorn water sampler at all three stations
and were taken at 6 different depths which are the subsurface (02m) 10m 20m 30m 40m
and 5Om At each station three replicates of water samples were taken back for laboratory
analysis Water samples were kept in 2 L polyethylene water bottles that has been acid
washed and were stored in cooler box filled with ice All samples were taken to the
laboratory for further analysis
33 Water quality parameters measured in-situ
Temperature dissolved oxygen (DO) pH electrical conductivity total dissolved
solids (TDS) and turbidity were taken using YSI Multiparameter Water Quality 6920 V2
The depths of each station were measured using depth finder Water transparency was also
measured using secchi disc at each station
34 Water quality parameters analysed ex-situ
341 Biochemical oxygen demand in five days (BODs)
BODs were determined by filling water samples into 300 ml BOD bottles DO
readings of the water samples were measured from the bottles All BOD bottles were
wrapped with aluminum foil to prevent light penetration and were kept in a cooler box for
5 days The initial DO value was recorded as DJ and on the 5th day the DO reading was
recorded as Ds The formula that was used for measuring BODs follows the protocol
outlined by APHA (1998)
11
BOD5 (mglL) = DJ - D5
Where DJ = Initial DO of sample immediately after preparation (mglL)
D5 = DO value after 5 days incubation at 25degC (mglL)
342 Total suspended solids (TSS)
Total suspended solids were analyzed using standard method APHA (1998) For
TSS analysis there was pre-fieldtrip sampling method and post-fieldtrip method For preshy
fieldtrip method glass fibre filter paper (GFIC 47 nun diameter 045 Ilm membrane) were
soaked in distilled water Each filter paper is placed on a piece of aluminum foil and was
dried in the oven at 103degC - 105degC overnight Filter paper then was allowed to cool for 10
minutes before weighing it using an analytical balance (ACCULAB ALC - 210) The
initial weight was recorded For post-fieldtrip method the glass fibre paper was placed on
the inter-plate of the filter funnel using a pair of forceps A known volume of water
samples was filtered using a vacuum pump After that filter paper was removed from the
filtration funnel and was placed back into the aluminum foil Filter paper was dried in the
oven at 103degC - 105degC overnight (APHA 1998) Filter paper was then taken out of the
oven and allowed to cool until room temperature before weighing The final reading of the
filtered glass fibre paper was recorded and TSS was calculated using the formula
w -wTSS (mglL) = J I
V
Where W = Initial weight of filter paper
WJ = Final weight of filter paper
V = Volume of water samples filtered (L)
12
4 Chlorophyll-a
The concentration of chlorophyll-a In the water samples were analyzed using
staDdard method APHA (1998) For chlorophyll-a analysis water samples were filtered
using vacuum pump Filter paper containing chlorophyll-a was taken from the vacuum
pump for analysis The samples were grinded by using a grinder and 5 - 6 mL of 90
acetone was added into the mortar Samples were grinded for about 5 minutes and all
materials in the mortar were placed into a capped test tube Ninety percent acetone was
added into the test tube to make up the volume to 10mL Test tube was folded with
aluminum foil and was placed in the refrigerator for 4 - 18 hours to facilitate complete
extraction of the pigments The liquid extracted was transferred into the centrifuge tube
The samples were placed into a centrifuge for about 10 minutes under 3000 rpm Optical
density was determined using spectrophotometer at wavelength of 750 nm 664 run 647
am and 630 nm Each extinctions for small turbidity blank was corrected by subtracting
750 nm from 664 nm and 630 run absorptions
The concentration of chlorophyll-a in the extract of the pigment after correction was
calculated using
Where E = the absorption in the respective wavelength
After determining the concentration of the chlorophyll-a in the extract the amount of
cblorophyll-a in the pigment per unit volume of water filtered was calculated as follows
13
Ca(v)Chlorophyll-a (Jg IL) = - shyv
Where Co = Chlorophyll-a pigment concentration in JgmL
v = Volume ofacetone in mL
v = Volume of samples in L
344 Ammonia-nitrogen (NH3-N)
For ammonia-nitrogen (NH3-N) the concentration was determined using standard
method 8038 Nessler Method (HACH 2000) A 25 mL prepared sample and 25 mL of
deionized water were filled into a separate 25 mL mixing graduated cylinder Three drops
of Mineral Stabilizer were added to both of the cylinders The cylinders were inverted
several times to mix the content After that 1 mL of Nessler reagent was pipetted into both
of the cylinders and the cylinders were inverted several times to mix the content A one-
minute reaction was started Both the solutions were poured into a square sample cell A
yellow colour formation will indicate the presence of ammonia When the timer expired
the blank was inserted into the square sample cell with the fill line facing the right The
reading at 425 run was zeroed The prepared sample was inserted into the cell holder of
Spectrophotometer DR 2800 (HACH 2000) with the fill line facing right and the reading
displayed was recorded
345 Nitrate (NO)-)
For nitrate analysis the concentration was determined using standard method 8192
Cadmium Reduction Method (HACH 2000) The sample was filled until the 15 mL mark
of a 25 mL graduated measuring cylinder The content of one Nitra Ver6 Nitrate Reagent
Pillow Powder was added into the cylinder and capped with a stopper The cylinder was
14
Pusat Khidmat Maldumat Akadfmil UN nsmMALAYSIA SARAWAI~
222 Dissolved Oxygen (DO)
DO is a very essential environmental factor that affects the entire production of a
reservoir and it is also an important indicator of water quality health of reservoir and also
ecological status as it is used for respiration and in biological and chemical reactions
(Mustapha 2008)
DO fluctuate from reservOIr to reservOIr and it is usually affected by
photosynthesis respiration and diel fluctuation In a study done by Ling (2012) it was
reported that the DO is higher at 05m depth at a11 stations in Batang Ai reservoir ranging
from 47 to 87 mgL due to the high phytoplankton photosynthesis rate An example of
diel fluctuation is shown in Kontagora reservoir where the DO is higher during the dry
season than the rainy season (Ibrahim 2009) This shows that the fluctuation also depends
on temperature depth wind and amount of biological activities such as decomposition In
Bakon Dam DO is high at the subsurface but dropped drastically until anoxic level at
depth 2 - 4m 2 years after impoundment and this is mainly due to the decomposition of
organic matter (Nyanti 2012)
223 pH
pH that is suitable for optimal production for inland waters should be about 65 to
85 (Ibrahim 2009) However changes in pH can affect the transfer of nutrients and affect
the condition ofwater quality (Li amp Xu 1995)
Fluctuations in pH can be caused by the photosynthesis process of phytoplanktons
as was reported in Batang Ai reservoir where all pH value was above 7 (Ling 2012)
Carbon dioxide produced by photosynthesis process will alter the pH of water as carbonic
acid will be formed when carbon dioxide reacts with water (Sangpal 2011)
5
Acidic effects in reservoirs can be caused by the transfer of cooler water from other
tributaries where the water is denser and lower in pH Nyanti (2012) reported the pH value
at Bakundam were all acidic ranging from 517-592 and the overall trend of pH in Bakun
dam decreases from upstream towards the dam (Nyanti et aI 2012)
224 Nutrients
Reservoirs are often have higher chances of getting higher element loading
compared to natural lakes as they have greater catchment area and high inflow rates
(Pawar amp Shembekar 2012) The concentration of nutrients varies from reservoir to
reservoir due to the differences in soil and vegetation in the catchment area (Li amp Xu
1995) Nutrients such as nitrates phosphates silicates and iron are important nutrients
required for aquatic growth but may also cause eutrophication and water quality problems
(Li amp Xu 1995) Eutrophication can occur easily in reservoir due to high input of nutrients
into the water and water quality of reservoir will be affected giving rise to unpleasant taste
and odour and affects the dissolution of other gases especially dissolved oxygen
(Mustapha 2008) According to Nyanti (2012) strong rotten egg smell discovered in
Bakun dam indicates high volume of hydrogen sulfide This observation is also supported
by Lourantou (2007) where an irritating odour smell occurs at a reservoir in Belgium
Nutrients input can also be affected by weather and season where nitrate was recorded at
higher values in Ujjani reservoir during post-monsoon season This may be caused by the
oxidation of nitrifying bacteria and biological nitrification Sulphate concentrations in the
dam were very high in both pre and post-monsoon which were probably caused by the
mineral rocks anthropogenically added and also by rain (Sangpal 2011) The phosphate
levels were found to be lower during the pre-monsoon and higher during the postshy
6
monsoon Phosphate leads to eutrophication that can cause unpleasant taste and odour to
the water (Sangpal 2011)
23 Impacts of hydroelectric dams on water quality
Hydroelectric dam has a direct impact to the water quality as it uses the flow rate of
a water course to produce electricity The building of hydroelectric dams has direct impact
towards the chemical thermal and physical parameters of the water body (Bunea 2012)
According to a study done by Bunea (2012) hydroelectric dams have relatively low DO
concentration mostly lower than 50 mglL because of the organic sediments that are left at
the bottom of the reservoir bottom during the initial filing Organic substances left at the
bottom of the reservoir bottom floor will absorb oxygen from the water in order to
decompose producing hydrogen sulphide carbon dioxide and methane (Bunea 2012)
Due to damming for hydroelectric generation water in a reservoir will undergo
stagnation which will lead to thermal stratification (Bunea 2012) According to a study
done by Elci (2008) thermal stratification of the reservoir involves the higher temperature
at the surface and lower temperatures at the bottom which suggests that thermal energy is
very slowly transferred to the bottom layers of the water body Thermal stratification act as
a barrier to re train mixing of the water column This causes an uneven concentration of
nutrients lack of light for photosynthesis at the hypolimnion and the water column may
become anoxic (Elci 2008)
Hydroelectric dams also greatly reduces the water self-purification capacity
According to Wei et al (2009) water self-purification mechanisms are affected by the
physical chemical and biotic processes in a reservoir However dam construction affects
all of the processes as the flow regime water quality and biotic community in the river In
other words dams slow down the river flow capacity block the river continuum and raise
7
water temperature which decreases the water self-purification capacity (Wei et aI 2009)
In a study done in China by Wei et al (2009) it is recorded that the Manwan-Dachaosan
dam has higher ammonia-nitrogen concentration due to the decreased water selfshy
purification capacity as compared to the pre-dam period This suggests that damming has
severely decreased the water self-purification capacity as it blocked the river continuum
8
30 Materials and Methods
31 Study Site
Bakun Hydroelectric Reservoir is a man-made reservoir which is located 60 km
west of Belaga Sarawak Malaysia (Figure 1) The dam was formed after the
impoundment of Balui River The reservoir has a catchment area of 14750 km2 and a total
capacity 43800000 m3 with a surface area of 695 km2 The dam is the second tallest
concrete-faced rockfill dam in the world
Three sampling stations namely stations 1 2 and 3 was selected in the reservoir
Station 1 is at the inundated estuary of the Linau River Station 2 is at the inundated Balui
River and Station 3 is located in the inundated Balui River as well but nearer to the dam
At each station sampling was conducted at 6 levels namely the subsurface 10m 20m
30m 4Om and 50m depths The coordinates of Bakun dam is at longitude 02deg45 23N and
latitude 114deg0347E The coordinates of every sampling station were recorded by the
Global Positioning System (GARMIN GPSMAP 62S) (Table 1) Sampling was carried
out twice the first sampling was from 21 SI August to 27th August 2015 and the second
sampling was 5th November to 11 th November 2015
9
i
EAST MALAYSIA
o
I
-I River I
-I Flooded Area
Station
0 Dam
kill I
Figure 1 Location of the three sampling stations at Bakun Reservoir
Table 1 Coordinates and locations of sampling stations
Station Coordinates Location
N 02deg 39 322 E 114deg 03 295 Estuary of Linau River
2 N 02deg 43 344 E 114deg 01 442 Balui River
3 N 02deg 43 4135 E 114deg 03 340 Further downstream of Balui River
10
32 Water samples
The water samples were taken using Van Dorn water sampler at all three stations
and were taken at 6 different depths which are the subsurface (02m) 10m 20m 30m 40m
and 5Om At each station three replicates of water samples were taken back for laboratory
analysis Water samples were kept in 2 L polyethylene water bottles that has been acid
washed and were stored in cooler box filled with ice All samples were taken to the
laboratory for further analysis
33 Water quality parameters measured in-situ
Temperature dissolved oxygen (DO) pH electrical conductivity total dissolved
solids (TDS) and turbidity were taken using YSI Multiparameter Water Quality 6920 V2
The depths of each station were measured using depth finder Water transparency was also
measured using secchi disc at each station
34 Water quality parameters analysed ex-situ
341 Biochemical oxygen demand in five days (BODs)
BODs were determined by filling water samples into 300 ml BOD bottles DO
readings of the water samples were measured from the bottles All BOD bottles were
wrapped with aluminum foil to prevent light penetration and were kept in a cooler box for
5 days The initial DO value was recorded as DJ and on the 5th day the DO reading was
recorded as Ds The formula that was used for measuring BODs follows the protocol
outlined by APHA (1998)
11
BOD5 (mglL) = DJ - D5
Where DJ = Initial DO of sample immediately after preparation (mglL)
D5 = DO value after 5 days incubation at 25degC (mglL)
342 Total suspended solids (TSS)
Total suspended solids were analyzed using standard method APHA (1998) For
TSS analysis there was pre-fieldtrip sampling method and post-fieldtrip method For preshy
fieldtrip method glass fibre filter paper (GFIC 47 nun diameter 045 Ilm membrane) were
soaked in distilled water Each filter paper is placed on a piece of aluminum foil and was
dried in the oven at 103degC - 105degC overnight Filter paper then was allowed to cool for 10
minutes before weighing it using an analytical balance (ACCULAB ALC - 210) The
initial weight was recorded For post-fieldtrip method the glass fibre paper was placed on
the inter-plate of the filter funnel using a pair of forceps A known volume of water
samples was filtered using a vacuum pump After that filter paper was removed from the
filtration funnel and was placed back into the aluminum foil Filter paper was dried in the
oven at 103degC - 105degC overnight (APHA 1998) Filter paper was then taken out of the
oven and allowed to cool until room temperature before weighing The final reading of the
filtered glass fibre paper was recorded and TSS was calculated using the formula
w -wTSS (mglL) = J I
V
Where W = Initial weight of filter paper
WJ = Final weight of filter paper
V = Volume of water samples filtered (L)
12
4 Chlorophyll-a
The concentration of chlorophyll-a In the water samples were analyzed using
staDdard method APHA (1998) For chlorophyll-a analysis water samples were filtered
using vacuum pump Filter paper containing chlorophyll-a was taken from the vacuum
pump for analysis The samples were grinded by using a grinder and 5 - 6 mL of 90
acetone was added into the mortar Samples were grinded for about 5 minutes and all
materials in the mortar were placed into a capped test tube Ninety percent acetone was
added into the test tube to make up the volume to 10mL Test tube was folded with
aluminum foil and was placed in the refrigerator for 4 - 18 hours to facilitate complete
extraction of the pigments The liquid extracted was transferred into the centrifuge tube
The samples were placed into a centrifuge for about 10 minutes under 3000 rpm Optical
density was determined using spectrophotometer at wavelength of 750 nm 664 run 647
am and 630 nm Each extinctions for small turbidity blank was corrected by subtracting
750 nm from 664 nm and 630 run absorptions
The concentration of chlorophyll-a in the extract of the pigment after correction was
calculated using
Where E = the absorption in the respective wavelength
After determining the concentration of the chlorophyll-a in the extract the amount of
cblorophyll-a in the pigment per unit volume of water filtered was calculated as follows
13
Ca(v)Chlorophyll-a (Jg IL) = - shyv
Where Co = Chlorophyll-a pigment concentration in JgmL
v = Volume ofacetone in mL
v = Volume of samples in L
344 Ammonia-nitrogen (NH3-N)
For ammonia-nitrogen (NH3-N) the concentration was determined using standard
method 8038 Nessler Method (HACH 2000) A 25 mL prepared sample and 25 mL of
deionized water were filled into a separate 25 mL mixing graduated cylinder Three drops
of Mineral Stabilizer were added to both of the cylinders The cylinders were inverted
several times to mix the content After that 1 mL of Nessler reagent was pipetted into both
of the cylinders and the cylinders were inverted several times to mix the content A one-
minute reaction was started Both the solutions were poured into a square sample cell A
yellow colour formation will indicate the presence of ammonia When the timer expired
the blank was inserted into the square sample cell with the fill line facing the right The
reading at 425 run was zeroed The prepared sample was inserted into the cell holder of
Spectrophotometer DR 2800 (HACH 2000) with the fill line facing right and the reading
displayed was recorded
345 Nitrate (NO)-)
For nitrate analysis the concentration was determined using standard method 8192
Cadmium Reduction Method (HACH 2000) The sample was filled until the 15 mL mark
of a 25 mL graduated measuring cylinder The content of one Nitra Ver6 Nitrate Reagent
Pillow Powder was added into the cylinder and capped with a stopper The cylinder was
14
Acidic effects in reservoirs can be caused by the transfer of cooler water from other
tributaries where the water is denser and lower in pH Nyanti (2012) reported the pH value
at Bakundam were all acidic ranging from 517-592 and the overall trend of pH in Bakun
dam decreases from upstream towards the dam (Nyanti et aI 2012)
224 Nutrients
Reservoirs are often have higher chances of getting higher element loading
compared to natural lakes as they have greater catchment area and high inflow rates
(Pawar amp Shembekar 2012) The concentration of nutrients varies from reservoir to
reservoir due to the differences in soil and vegetation in the catchment area (Li amp Xu
1995) Nutrients such as nitrates phosphates silicates and iron are important nutrients
required for aquatic growth but may also cause eutrophication and water quality problems
(Li amp Xu 1995) Eutrophication can occur easily in reservoir due to high input of nutrients
into the water and water quality of reservoir will be affected giving rise to unpleasant taste
and odour and affects the dissolution of other gases especially dissolved oxygen
(Mustapha 2008) According to Nyanti (2012) strong rotten egg smell discovered in
Bakun dam indicates high volume of hydrogen sulfide This observation is also supported
by Lourantou (2007) where an irritating odour smell occurs at a reservoir in Belgium
Nutrients input can also be affected by weather and season where nitrate was recorded at
higher values in Ujjani reservoir during post-monsoon season This may be caused by the
oxidation of nitrifying bacteria and biological nitrification Sulphate concentrations in the
dam were very high in both pre and post-monsoon which were probably caused by the
mineral rocks anthropogenically added and also by rain (Sangpal 2011) The phosphate
levels were found to be lower during the pre-monsoon and higher during the postshy
6
monsoon Phosphate leads to eutrophication that can cause unpleasant taste and odour to
the water (Sangpal 2011)
23 Impacts of hydroelectric dams on water quality
Hydroelectric dam has a direct impact to the water quality as it uses the flow rate of
a water course to produce electricity The building of hydroelectric dams has direct impact
towards the chemical thermal and physical parameters of the water body (Bunea 2012)
According to a study done by Bunea (2012) hydroelectric dams have relatively low DO
concentration mostly lower than 50 mglL because of the organic sediments that are left at
the bottom of the reservoir bottom during the initial filing Organic substances left at the
bottom of the reservoir bottom floor will absorb oxygen from the water in order to
decompose producing hydrogen sulphide carbon dioxide and methane (Bunea 2012)
Due to damming for hydroelectric generation water in a reservoir will undergo
stagnation which will lead to thermal stratification (Bunea 2012) According to a study
done by Elci (2008) thermal stratification of the reservoir involves the higher temperature
at the surface and lower temperatures at the bottom which suggests that thermal energy is
very slowly transferred to the bottom layers of the water body Thermal stratification act as
a barrier to re train mixing of the water column This causes an uneven concentration of
nutrients lack of light for photosynthesis at the hypolimnion and the water column may
become anoxic (Elci 2008)
Hydroelectric dams also greatly reduces the water self-purification capacity
According to Wei et al (2009) water self-purification mechanisms are affected by the
physical chemical and biotic processes in a reservoir However dam construction affects
all of the processes as the flow regime water quality and biotic community in the river In
other words dams slow down the river flow capacity block the river continuum and raise
7
water temperature which decreases the water self-purification capacity (Wei et aI 2009)
In a study done in China by Wei et al (2009) it is recorded that the Manwan-Dachaosan
dam has higher ammonia-nitrogen concentration due to the decreased water selfshy
purification capacity as compared to the pre-dam period This suggests that damming has
severely decreased the water self-purification capacity as it blocked the river continuum
8
30 Materials and Methods
31 Study Site
Bakun Hydroelectric Reservoir is a man-made reservoir which is located 60 km
west of Belaga Sarawak Malaysia (Figure 1) The dam was formed after the
impoundment of Balui River The reservoir has a catchment area of 14750 km2 and a total
capacity 43800000 m3 with a surface area of 695 km2 The dam is the second tallest
concrete-faced rockfill dam in the world
Three sampling stations namely stations 1 2 and 3 was selected in the reservoir
Station 1 is at the inundated estuary of the Linau River Station 2 is at the inundated Balui
River and Station 3 is located in the inundated Balui River as well but nearer to the dam
At each station sampling was conducted at 6 levels namely the subsurface 10m 20m
30m 4Om and 50m depths The coordinates of Bakun dam is at longitude 02deg45 23N and
latitude 114deg0347E The coordinates of every sampling station were recorded by the
Global Positioning System (GARMIN GPSMAP 62S) (Table 1) Sampling was carried
out twice the first sampling was from 21 SI August to 27th August 2015 and the second
sampling was 5th November to 11 th November 2015
9
i
EAST MALAYSIA
o
I
-I River I
-I Flooded Area
Station
0 Dam
kill I
Figure 1 Location of the three sampling stations at Bakun Reservoir
Table 1 Coordinates and locations of sampling stations
Station Coordinates Location
N 02deg 39 322 E 114deg 03 295 Estuary of Linau River
2 N 02deg 43 344 E 114deg 01 442 Balui River
3 N 02deg 43 4135 E 114deg 03 340 Further downstream of Balui River
10
32 Water samples
The water samples were taken using Van Dorn water sampler at all three stations
and were taken at 6 different depths which are the subsurface (02m) 10m 20m 30m 40m
and 5Om At each station three replicates of water samples were taken back for laboratory
analysis Water samples were kept in 2 L polyethylene water bottles that has been acid
washed and were stored in cooler box filled with ice All samples were taken to the
laboratory for further analysis
33 Water quality parameters measured in-situ
Temperature dissolved oxygen (DO) pH electrical conductivity total dissolved
solids (TDS) and turbidity were taken using YSI Multiparameter Water Quality 6920 V2
The depths of each station were measured using depth finder Water transparency was also
measured using secchi disc at each station
34 Water quality parameters analysed ex-situ
341 Biochemical oxygen demand in five days (BODs)
BODs were determined by filling water samples into 300 ml BOD bottles DO
readings of the water samples were measured from the bottles All BOD bottles were
wrapped with aluminum foil to prevent light penetration and were kept in a cooler box for
5 days The initial DO value was recorded as DJ and on the 5th day the DO reading was
recorded as Ds The formula that was used for measuring BODs follows the protocol
outlined by APHA (1998)
11
BOD5 (mglL) = DJ - D5
Where DJ = Initial DO of sample immediately after preparation (mglL)
D5 = DO value after 5 days incubation at 25degC (mglL)
342 Total suspended solids (TSS)
Total suspended solids were analyzed using standard method APHA (1998) For
TSS analysis there was pre-fieldtrip sampling method and post-fieldtrip method For preshy
fieldtrip method glass fibre filter paper (GFIC 47 nun diameter 045 Ilm membrane) were
soaked in distilled water Each filter paper is placed on a piece of aluminum foil and was
dried in the oven at 103degC - 105degC overnight Filter paper then was allowed to cool for 10
minutes before weighing it using an analytical balance (ACCULAB ALC - 210) The
initial weight was recorded For post-fieldtrip method the glass fibre paper was placed on
the inter-plate of the filter funnel using a pair of forceps A known volume of water
samples was filtered using a vacuum pump After that filter paper was removed from the
filtration funnel and was placed back into the aluminum foil Filter paper was dried in the
oven at 103degC - 105degC overnight (APHA 1998) Filter paper was then taken out of the
oven and allowed to cool until room temperature before weighing The final reading of the
filtered glass fibre paper was recorded and TSS was calculated using the formula
w -wTSS (mglL) = J I
V
Where W = Initial weight of filter paper
WJ = Final weight of filter paper
V = Volume of water samples filtered (L)
12
4 Chlorophyll-a
The concentration of chlorophyll-a In the water samples were analyzed using
staDdard method APHA (1998) For chlorophyll-a analysis water samples were filtered
using vacuum pump Filter paper containing chlorophyll-a was taken from the vacuum
pump for analysis The samples were grinded by using a grinder and 5 - 6 mL of 90
acetone was added into the mortar Samples were grinded for about 5 minutes and all
materials in the mortar were placed into a capped test tube Ninety percent acetone was
added into the test tube to make up the volume to 10mL Test tube was folded with
aluminum foil and was placed in the refrigerator for 4 - 18 hours to facilitate complete
extraction of the pigments The liquid extracted was transferred into the centrifuge tube
The samples were placed into a centrifuge for about 10 minutes under 3000 rpm Optical
density was determined using spectrophotometer at wavelength of 750 nm 664 run 647
am and 630 nm Each extinctions for small turbidity blank was corrected by subtracting
750 nm from 664 nm and 630 run absorptions
The concentration of chlorophyll-a in the extract of the pigment after correction was
calculated using
Where E = the absorption in the respective wavelength
After determining the concentration of the chlorophyll-a in the extract the amount of
cblorophyll-a in the pigment per unit volume of water filtered was calculated as follows
13
Ca(v)Chlorophyll-a (Jg IL) = - shyv
Where Co = Chlorophyll-a pigment concentration in JgmL
v = Volume ofacetone in mL
v = Volume of samples in L
344 Ammonia-nitrogen (NH3-N)
For ammonia-nitrogen (NH3-N) the concentration was determined using standard
method 8038 Nessler Method (HACH 2000) A 25 mL prepared sample and 25 mL of
deionized water were filled into a separate 25 mL mixing graduated cylinder Three drops
of Mineral Stabilizer were added to both of the cylinders The cylinders were inverted
several times to mix the content After that 1 mL of Nessler reagent was pipetted into both
of the cylinders and the cylinders were inverted several times to mix the content A one-
minute reaction was started Both the solutions were poured into a square sample cell A
yellow colour formation will indicate the presence of ammonia When the timer expired
the blank was inserted into the square sample cell with the fill line facing the right The
reading at 425 run was zeroed The prepared sample was inserted into the cell holder of
Spectrophotometer DR 2800 (HACH 2000) with the fill line facing right and the reading
displayed was recorded
345 Nitrate (NO)-)
For nitrate analysis the concentration was determined using standard method 8192
Cadmium Reduction Method (HACH 2000) The sample was filled until the 15 mL mark
of a 25 mL graduated measuring cylinder The content of one Nitra Ver6 Nitrate Reagent
Pillow Powder was added into the cylinder and capped with a stopper The cylinder was
14
monsoon Phosphate leads to eutrophication that can cause unpleasant taste and odour to
the water (Sangpal 2011)
23 Impacts of hydroelectric dams on water quality
Hydroelectric dam has a direct impact to the water quality as it uses the flow rate of
a water course to produce electricity The building of hydroelectric dams has direct impact
towards the chemical thermal and physical parameters of the water body (Bunea 2012)
According to a study done by Bunea (2012) hydroelectric dams have relatively low DO
concentration mostly lower than 50 mglL because of the organic sediments that are left at
the bottom of the reservoir bottom during the initial filing Organic substances left at the
bottom of the reservoir bottom floor will absorb oxygen from the water in order to
decompose producing hydrogen sulphide carbon dioxide and methane (Bunea 2012)
Due to damming for hydroelectric generation water in a reservoir will undergo
stagnation which will lead to thermal stratification (Bunea 2012) According to a study
done by Elci (2008) thermal stratification of the reservoir involves the higher temperature
at the surface and lower temperatures at the bottom which suggests that thermal energy is
very slowly transferred to the bottom layers of the water body Thermal stratification act as
a barrier to re train mixing of the water column This causes an uneven concentration of
nutrients lack of light for photosynthesis at the hypolimnion and the water column may
become anoxic (Elci 2008)
Hydroelectric dams also greatly reduces the water self-purification capacity
According to Wei et al (2009) water self-purification mechanisms are affected by the
physical chemical and biotic processes in a reservoir However dam construction affects
all of the processes as the flow regime water quality and biotic community in the river In
other words dams slow down the river flow capacity block the river continuum and raise
7
water temperature which decreases the water self-purification capacity (Wei et aI 2009)
In a study done in China by Wei et al (2009) it is recorded that the Manwan-Dachaosan
dam has higher ammonia-nitrogen concentration due to the decreased water selfshy
purification capacity as compared to the pre-dam period This suggests that damming has
severely decreased the water self-purification capacity as it blocked the river continuum
8
30 Materials and Methods
31 Study Site
Bakun Hydroelectric Reservoir is a man-made reservoir which is located 60 km
west of Belaga Sarawak Malaysia (Figure 1) The dam was formed after the
impoundment of Balui River The reservoir has a catchment area of 14750 km2 and a total
capacity 43800000 m3 with a surface area of 695 km2 The dam is the second tallest
concrete-faced rockfill dam in the world
Three sampling stations namely stations 1 2 and 3 was selected in the reservoir
Station 1 is at the inundated estuary of the Linau River Station 2 is at the inundated Balui
River and Station 3 is located in the inundated Balui River as well but nearer to the dam
At each station sampling was conducted at 6 levels namely the subsurface 10m 20m
30m 4Om and 50m depths The coordinates of Bakun dam is at longitude 02deg45 23N and
latitude 114deg0347E The coordinates of every sampling station were recorded by the
Global Positioning System (GARMIN GPSMAP 62S) (Table 1) Sampling was carried
out twice the first sampling was from 21 SI August to 27th August 2015 and the second
sampling was 5th November to 11 th November 2015
9
i
EAST MALAYSIA
o
I
-I River I
-I Flooded Area
Station
0 Dam
kill I
Figure 1 Location of the three sampling stations at Bakun Reservoir
Table 1 Coordinates and locations of sampling stations
Station Coordinates Location
N 02deg 39 322 E 114deg 03 295 Estuary of Linau River
2 N 02deg 43 344 E 114deg 01 442 Balui River
3 N 02deg 43 4135 E 114deg 03 340 Further downstream of Balui River
10
32 Water samples
The water samples were taken using Van Dorn water sampler at all three stations
and were taken at 6 different depths which are the subsurface (02m) 10m 20m 30m 40m
and 5Om At each station three replicates of water samples were taken back for laboratory
analysis Water samples were kept in 2 L polyethylene water bottles that has been acid
washed and were stored in cooler box filled with ice All samples were taken to the
laboratory for further analysis
33 Water quality parameters measured in-situ
Temperature dissolved oxygen (DO) pH electrical conductivity total dissolved
solids (TDS) and turbidity were taken using YSI Multiparameter Water Quality 6920 V2
The depths of each station were measured using depth finder Water transparency was also
measured using secchi disc at each station
34 Water quality parameters analysed ex-situ
341 Biochemical oxygen demand in five days (BODs)
BODs were determined by filling water samples into 300 ml BOD bottles DO
readings of the water samples were measured from the bottles All BOD bottles were
wrapped with aluminum foil to prevent light penetration and were kept in a cooler box for
5 days The initial DO value was recorded as DJ and on the 5th day the DO reading was
recorded as Ds The formula that was used for measuring BODs follows the protocol
outlined by APHA (1998)
11
BOD5 (mglL) = DJ - D5
Where DJ = Initial DO of sample immediately after preparation (mglL)
D5 = DO value after 5 days incubation at 25degC (mglL)
342 Total suspended solids (TSS)
Total suspended solids were analyzed using standard method APHA (1998) For
TSS analysis there was pre-fieldtrip sampling method and post-fieldtrip method For preshy
fieldtrip method glass fibre filter paper (GFIC 47 nun diameter 045 Ilm membrane) were
soaked in distilled water Each filter paper is placed on a piece of aluminum foil and was
dried in the oven at 103degC - 105degC overnight Filter paper then was allowed to cool for 10
minutes before weighing it using an analytical balance (ACCULAB ALC - 210) The
initial weight was recorded For post-fieldtrip method the glass fibre paper was placed on
the inter-plate of the filter funnel using a pair of forceps A known volume of water
samples was filtered using a vacuum pump After that filter paper was removed from the
filtration funnel and was placed back into the aluminum foil Filter paper was dried in the
oven at 103degC - 105degC overnight (APHA 1998) Filter paper was then taken out of the
oven and allowed to cool until room temperature before weighing The final reading of the
filtered glass fibre paper was recorded and TSS was calculated using the formula
w -wTSS (mglL) = J I
V
Where W = Initial weight of filter paper
WJ = Final weight of filter paper
V = Volume of water samples filtered (L)
12
4 Chlorophyll-a
The concentration of chlorophyll-a In the water samples were analyzed using
staDdard method APHA (1998) For chlorophyll-a analysis water samples were filtered
using vacuum pump Filter paper containing chlorophyll-a was taken from the vacuum
pump for analysis The samples were grinded by using a grinder and 5 - 6 mL of 90
acetone was added into the mortar Samples were grinded for about 5 minutes and all
materials in the mortar were placed into a capped test tube Ninety percent acetone was
added into the test tube to make up the volume to 10mL Test tube was folded with
aluminum foil and was placed in the refrigerator for 4 - 18 hours to facilitate complete
extraction of the pigments The liquid extracted was transferred into the centrifuge tube
The samples were placed into a centrifuge for about 10 minutes under 3000 rpm Optical
density was determined using spectrophotometer at wavelength of 750 nm 664 run 647
am and 630 nm Each extinctions for small turbidity blank was corrected by subtracting
750 nm from 664 nm and 630 run absorptions
The concentration of chlorophyll-a in the extract of the pigment after correction was
calculated using
Where E = the absorption in the respective wavelength
After determining the concentration of the chlorophyll-a in the extract the amount of
cblorophyll-a in the pigment per unit volume of water filtered was calculated as follows
13
Ca(v)Chlorophyll-a (Jg IL) = - shyv
Where Co = Chlorophyll-a pigment concentration in JgmL
v = Volume ofacetone in mL
v = Volume of samples in L
344 Ammonia-nitrogen (NH3-N)
For ammonia-nitrogen (NH3-N) the concentration was determined using standard
method 8038 Nessler Method (HACH 2000) A 25 mL prepared sample and 25 mL of
deionized water were filled into a separate 25 mL mixing graduated cylinder Three drops
of Mineral Stabilizer were added to both of the cylinders The cylinders were inverted
several times to mix the content After that 1 mL of Nessler reagent was pipetted into both
of the cylinders and the cylinders were inverted several times to mix the content A one-
minute reaction was started Both the solutions were poured into a square sample cell A
yellow colour formation will indicate the presence of ammonia When the timer expired
the blank was inserted into the square sample cell with the fill line facing the right The
reading at 425 run was zeroed The prepared sample was inserted into the cell holder of
Spectrophotometer DR 2800 (HACH 2000) with the fill line facing right and the reading
displayed was recorded
345 Nitrate (NO)-)
For nitrate analysis the concentration was determined using standard method 8192
Cadmium Reduction Method (HACH 2000) The sample was filled until the 15 mL mark
of a 25 mL graduated measuring cylinder The content of one Nitra Ver6 Nitrate Reagent
Pillow Powder was added into the cylinder and capped with a stopper The cylinder was
14
water temperature which decreases the water self-purification capacity (Wei et aI 2009)
In a study done in China by Wei et al (2009) it is recorded that the Manwan-Dachaosan
dam has higher ammonia-nitrogen concentration due to the decreased water selfshy
purification capacity as compared to the pre-dam period This suggests that damming has
severely decreased the water self-purification capacity as it blocked the river continuum
8
30 Materials and Methods
31 Study Site
Bakun Hydroelectric Reservoir is a man-made reservoir which is located 60 km
west of Belaga Sarawak Malaysia (Figure 1) The dam was formed after the
impoundment of Balui River The reservoir has a catchment area of 14750 km2 and a total
capacity 43800000 m3 with a surface area of 695 km2 The dam is the second tallest
concrete-faced rockfill dam in the world
Three sampling stations namely stations 1 2 and 3 was selected in the reservoir
Station 1 is at the inundated estuary of the Linau River Station 2 is at the inundated Balui
River and Station 3 is located in the inundated Balui River as well but nearer to the dam
At each station sampling was conducted at 6 levels namely the subsurface 10m 20m
30m 4Om and 50m depths The coordinates of Bakun dam is at longitude 02deg45 23N and
latitude 114deg0347E The coordinates of every sampling station were recorded by the
Global Positioning System (GARMIN GPSMAP 62S) (Table 1) Sampling was carried
out twice the first sampling was from 21 SI August to 27th August 2015 and the second
sampling was 5th November to 11 th November 2015
9
i
EAST MALAYSIA
o
I
-I River I
-I Flooded Area
Station
0 Dam
kill I
Figure 1 Location of the three sampling stations at Bakun Reservoir
Table 1 Coordinates and locations of sampling stations
Station Coordinates Location
N 02deg 39 322 E 114deg 03 295 Estuary of Linau River
2 N 02deg 43 344 E 114deg 01 442 Balui River
3 N 02deg 43 4135 E 114deg 03 340 Further downstream of Balui River
10
32 Water samples
The water samples were taken using Van Dorn water sampler at all three stations
and were taken at 6 different depths which are the subsurface (02m) 10m 20m 30m 40m
and 5Om At each station three replicates of water samples were taken back for laboratory
analysis Water samples were kept in 2 L polyethylene water bottles that has been acid
washed and were stored in cooler box filled with ice All samples were taken to the
laboratory for further analysis
33 Water quality parameters measured in-situ
Temperature dissolved oxygen (DO) pH electrical conductivity total dissolved
solids (TDS) and turbidity were taken using YSI Multiparameter Water Quality 6920 V2
The depths of each station were measured using depth finder Water transparency was also
measured using secchi disc at each station
34 Water quality parameters analysed ex-situ
341 Biochemical oxygen demand in five days (BODs)
BODs were determined by filling water samples into 300 ml BOD bottles DO
readings of the water samples were measured from the bottles All BOD bottles were
wrapped with aluminum foil to prevent light penetration and were kept in a cooler box for
5 days The initial DO value was recorded as DJ and on the 5th day the DO reading was
recorded as Ds The formula that was used for measuring BODs follows the protocol
outlined by APHA (1998)
11
BOD5 (mglL) = DJ - D5
Where DJ = Initial DO of sample immediately after preparation (mglL)
D5 = DO value after 5 days incubation at 25degC (mglL)
342 Total suspended solids (TSS)
Total suspended solids were analyzed using standard method APHA (1998) For
TSS analysis there was pre-fieldtrip sampling method and post-fieldtrip method For preshy
fieldtrip method glass fibre filter paper (GFIC 47 nun diameter 045 Ilm membrane) were
soaked in distilled water Each filter paper is placed on a piece of aluminum foil and was
dried in the oven at 103degC - 105degC overnight Filter paper then was allowed to cool for 10
minutes before weighing it using an analytical balance (ACCULAB ALC - 210) The
initial weight was recorded For post-fieldtrip method the glass fibre paper was placed on
the inter-plate of the filter funnel using a pair of forceps A known volume of water
samples was filtered using a vacuum pump After that filter paper was removed from the
filtration funnel and was placed back into the aluminum foil Filter paper was dried in the
oven at 103degC - 105degC overnight (APHA 1998) Filter paper was then taken out of the
oven and allowed to cool until room temperature before weighing The final reading of the
filtered glass fibre paper was recorded and TSS was calculated using the formula
w -wTSS (mglL) = J I
V
Where W = Initial weight of filter paper
WJ = Final weight of filter paper
V = Volume of water samples filtered (L)
12
4 Chlorophyll-a
The concentration of chlorophyll-a In the water samples were analyzed using
staDdard method APHA (1998) For chlorophyll-a analysis water samples were filtered
using vacuum pump Filter paper containing chlorophyll-a was taken from the vacuum
pump for analysis The samples were grinded by using a grinder and 5 - 6 mL of 90
acetone was added into the mortar Samples were grinded for about 5 minutes and all
materials in the mortar were placed into a capped test tube Ninety percent acetone was
added into the test tube to make up the volume to 10mL Test tube was folded with
aluminum foil and was placed in the refrigerator for 4 - 18 hours to facilitate complete
extraction of the pigments The liquid extracted was transferred into the centrifuge tube
The samples were placed into a centrifuge for about 10 minutes under 3000 rpm Optical
density was determined using spectrophotometer at wavelength of 750 nm 664 run 647
am and 630 nm Each extinctions for small turbidity blank was corrected by subtracting
750 nm from 664 nm and 630 run absorptions
The concentration of chlorophyll-a in the extract of the pigment after correction was
calculated using
Where E = the absorption in the respective wavelength
After determining the concentration of the chlorophyll-a in the extract the amount of
cblorophyll-a in the pigment per unit volume of water filtered was calculated as follows
13
Ca(v)Chlorophyll-a (Jg IL) = - shyv
Where Co = Chlorophyll-a pigment concentration in JgmL
v = Volume ofacetone in mL
v = Volume of samples in L
344 Ammonia-nitrogen (NH3-N)
For ammonia-nitrogen (NH3-N) the concentration was determined using standard
method 8038 Nessler Method (HACH 2000) A 25 mL prepared sample and 25 mL of
deionized water were filled into a separate 25 mL mixing graduated cylinder Three drops
of Mineral Stabilizer were added to both of the cylinders The cylinders were inverted
several times to mix the content After that 1 mL of Nessler reagent was pipetted into both
of the cylinders and the cylinders were inverted several times to mix the content A one-
minute reaction was started Both the solutions were poured into a square sample cell A
yellow colour formation will indicate the presence of ammonia When the timer expired
the blank was inserted into the square sample cell with the fill line facing the right The
reading at 425 run was zeroed The prepared sample was inserted into the cell holder of
Spectrophotometer DR 2800 (HACH 2000) with the fill line facing right and the reading
displayed was recorded
345 Nitrate (NO)-)
For nitrate analysis the concentration was determined using standard method 8192
Cadmium Reduction Method (HACH 2000) The sample was filled until the 15 mL mark
of a 25 mL graduated measuring cylinder The content of one Nitra Ver6 Nitrate Reagent
Pillow Powder was added into the cylinder and capped with a stopper The cylinder was
14
30 Materials and Methods
31 Study Site
Bakun Hydroelectric Reservoir is a man-made reservoir which is located 60 km
west of Belaga Sarawak Malaysia (Figure 1) The dam was formed after the
impoundment of Balui River The reservoir has a catchment area of 14750 km2 and a total
capacity 43800000 m3 with a surface area of 695 km2 The dam is the second tallest
concrete-faced rockfill dam in the world
Three sampling stations namely stations 1 2 and 3 was selected in the reservoir
Station 1 is at the inundated estuary of the Linau River Station 2 is at the inundated Balui
River and Station 3 is located in the inundated Balui River as well but nearer to the dam
At each station sampling was conducted at 6 levels namely the subsurface 10m 20m
30m 4Om and 50m depths The coordinates of Bakun dam is at longitude 02deg45 23N and
latitude 114deg0347E The coordinates of every sampling station were recorded by the
Global Positioning System (GARMIN GPSMAP 62S) (Table 1) Sampling was carried
out twice the first sampling was from 21 SI August to 27th August 2015 and the second
sampling was 5th November to 11 th November 2015
9
i
EAST MALAYSIA
o
I
-I River I
-I Flooded Area
Station
0 Dam
kill I
Figure 1 Location of the three sampling stations at Bakun Reservoir
Table 1 Coordinates and locations of sampling stations
Station Coordinates Location
N 02deg 39 322 E 114deg 03 295 Estuary of Linau River
2 N 02deg 43 344 E 114deg 01 442 Balui River
3 N 02deg 43 4135 E 114deg 03 340 Further downstream of Balui River
10
32 Water samples
The water samples were taken using Van Dorn water sampler at all three stations
and were taken at 6 different depths which are the subsurface (02m) 10m 20m 30m 40m
and 5Om At each station three replicates of water samples were taken back for laboratory
analysis Water samples were kept in 2 L polyethylene water bottles that has been acid
washed and were stored in cooler box filled with ice All samples were taken to the
laboratory for further analysis
33 Water quality parameters measured in-situ
Temperature dissolved oxygen (DO) pH electrical conductivity total dissolved
solids (TDS) and turbidity were taken using YSI Multiparameter Water Quality 6920 V2
The depths of each station were measured using depth finder Water transparency was also
measured using secchi disc at each station
34 Water quality parameters analysed ex-situ
341 Biochemical oxygen demand in five days (BODs)
BODs were determined by filling water samples into 300 ml BOD bottles DO
readings of the water samples were measured from the bottles All BOD bottles were
wrapped with aluminum foil to prevent light penetration and were kept in a cooler box for
5 days The initial DO value was recorded as DJ and on the 5th day the DO reading was
recorded as Ds The formula that was used for measuring BODs follows the protocol
outlined by APHA (1998)
11
BOD5 (mglL) = DJ - D5
Where DJ = Initial DO of sample immediately after preparation (mglL)
D5 = DO value after 5 days incubation at 25degC (mglL)
342 Total suspended solids (TSS)
Total suspended solids were analyzed using standard method APHA (1998) For
TSS analysis there was pre-fieldtrip sampling method and post-fieldtrip method For preshy
fieldtrip method glass fibre filter paper (GFIC 47 nun diameter 045 Ilm membrane) were
soaked in distilled water Each filter paper is placed on a piece of aluminum foil and was
dried in the oven at 103degC - 105degC overnight Filter paper then was allowed to cool for 10
minutes before weighing it using an analytical balance (ACCULAB ALC - 210) The
initial weight was recorded For post-fieldtrip method the glass fibre paper was placed on
the inter-plate of the filter funnel using a pair of forceps A known volume of water
samples was filtered using a vacuum pump After that filter paper was removed from the
filtration funnel and was placed back into the aluminum foil Filter paper was dried in the
oven at 103degC - 105degC overnight (APHA 1998) Filter paper was then taken out of the
oven and allowed to cool until room temperature before weighing The final reading of the
filtered glass fibre paper was recorded and TSS was calculated using the formula
w -wTSS (mglL) = J I
V
Where W = Initial weight of filter paper
WJ = Final weight of filter paper
V = Volume of water samples filtered (L)
12
4 Chlorophyll-a
The concentration of chlorophyll-a In the water samples were analyzed using
staDdard method APHA (1998) For chlorophyll-a analysis water samples were filtered
using vacuum pump Filter paper containing chlorophyll-a was taken from the vacuum
pump for analysis The samples were grinded by using a grinder and 5 - 6 mL of 90
acetone was added into the mortar Samples were grinded for about 5 minutes and all
materials in the mortar were placed into a capped test tube Ninety percent acetone was
added into the test tube to make up the volume to 10mL Test tube was folded with
aluminum foil and was placed in the refrigerator for 4 - 18 hours to facilitate complete
extraction of the pigments The liquid extracted was transferred into the centrifuge tube
The samples were placed into a centrifuge for about 10 minutes under 3000 rpm Optical
density was determined using spectrophotometer at wavelength of 750 nm 664 run 647
am and 630 nm Each extinctions for small turbidity blank was corrected by subtracting
750 nm from 664 nm and 630 run absorptions
The concentration of chlorophyll-a in the extract of the pigment after correction was
calculated using
Where E = the absorption in the respective wavelength
After determining the concentration of the chlorophyll-a in the extract the amount of
cblorophyll-a in the pigment per unit volume of water filtered was calculated as follows
13
Ca(v)Chlorophyll-a (Jg IL) = - shyv
Where Co = Chlorophyll-a pigment concentration in JgmL
v = Volume ofacetone in mL
v = Volume of samples in L
344 Ammonia-nitrogen (NH3-N)
For ammonia-nitrogen (NH3-N) the concentration was determined using standard
method 8038 Nessler Method (HACH 2000) A 25 mL prepared sample and 25 mL of
deionized water were filled into a separate 25 mL mixing graduated cylinder Three drops
of Mineral Stabilizer were added to both of the cylinders The cylinders were inverted
several times to mix the content After that 1 mL of Nessler reagent was pipetted into both
of the cylinders and the cylinders were inverted several times to mix the content A one-
minute reaction was started Both the solutions were poured into a square sample cell A
yellow colour formation will indicate the presence of ammonia When the timer expired
the blank was inserted into the square sample cell with the fill line facing the right The
reading at 425 run was zeroed The prepared sample was inserted into the cell holder of
Spectrophotometer DR 2800 (HACH 2000) with the fill line facing right and the reading
displayed was recorded
345 Nitrate (NO)-)
For nitrate analysis the concentration was determined using standard method 8192
Cadmium Reduction Method (HACH 2000) The sample was filled until the 15 mL mark
of a 25 mL graduated measuring cylinder The content of one Nitra Ver6 Nitrate Reagent
Pillow Powder was added into the cylinder and capped with a stopper The cylinder was
14
EAST MALAYSIA
o
I
-I River I
-I Flooded Area
Station
0 Dam
kill I
Figure 1 Location of the three sampling stations at Bakun Reservoir
Table 1 Coordinates and locations of sampling stations
Station Coordinates Location
N 02deg 39 322 E 114deg 03 295 Estuary of Linau River
2 N 02deg 43 344 E 114deg 01 442 Balui River
3 N 02deg 43 4135 E 114deg 03 340 Further downstream of Balui River
10
32 Water samples
The water samples were taken using Van Dorn water sampler at all three stations
and were taken at 6 different depths which are the subsurface (02m) 10m 20m 30m 40m
and 5Om At each station three replicates of water samples were taken back for laboratory
analysis Water samples were kept in 2 L polyethylene water bottles that has been acid
washed and were stored in cooler box filled with ice All samples were taken to the
laboratory for further analysis
33 Water quality parameters measured in-situ
Temperature dissolved oxygen (DO) pH electrical conductivity total dissolved
solids (TDS) and turbidity were taken using YSI Multiparameter Water Quality 6920 V2
The depths of each station were measured using depth finder Water transparency was also
measured using secchi disc at each station
34 Water quality parameters analysed ex-situ
341 Biochemical oxygen demand in five days (BODs)
BODs were determined by filling water samples into 300 ml BOD bottles DO
readings of the water samples were measured from the bottles All BOD bottles were
wrapped with aluminum foil to prevent light penetration and were kept in a cooler box for
5 days The initial DO value was recorded as DJ and on the 5th day the DO reading was
recorded as Ds The formula that was used for measuring BODs follows the protocol
outlined by APHA (1998)
11
BOD5 (mglL) = DJ - D5
Where DJ = Initial DO of sample immediately after preparation (mglL)
D5 = DO value after 5 days incubation at 25degC (mglL)
342 Total suspended solids (TSS)
Total suspended solids were analyzed using standard method APHA (1998) For
TSS analysis there was pre-fieldtrip sampling method and post-fieldtrip method For preshy
fieldtrip method glass fibre filter paper (GFIC 47 nun diameter 045 Ilm membrane) were
soaked in distilled water Each filter paper is placed on a piece of aluminum foil and was
dried in the oven at 103degC - 105degC overnight Filter paper then was allowed to cool for 10
minutes before weighing it using an analytical balance (ACCULAB ALC - 210) The
initial weight was recorded For post-fieldtrip method the glass fibre paper was placed on
the inter-plate of the filter funnel using a pair of forceps A known volume of water
samples was filtered using a vacuum pump After that filter paper was removed from the
filtration funnel and was placed back into the aluminum foil Filter paper was dried in the
oven at 103degC - 105degC overnight (APHA 1998) Filter paper was then taken out of the
oven and allowed to cool until room temperature before weighing The final reading of the
filtered glass fibre paper was recorded and TSS was calculated using the formula
w -wTSS (mglL) = J I
V
Where W = Initial weight of filter paper
WJ = Final weight of filter paper
V = Volume of water samples filtered (L)
12
4 Chlorophyll-a
The concentration of chlorophyll-a In the water samples were analyzed using
staDdard method APHA (1998) For chlorophyll-a analysis water samples were filtered
using vacuum pump Filter paper containing chlorophyll-a was taken from the vacuum
pump for analysis The samples were grinded by using a grinder and 5 - 6 mL of 90
acetone was added into the mortar Samples were grinded for about 5 minutes and all
materials in the mortar were placed into a capped test tube Ninety percent acetone was
added into the test tube to make up the volume to 10mL Test tube was folded with
aluminum foil and was placed in the refrigerator for 4 - 18 hours to facilitate complete
extraction of the pigments The liquid extracted was transferred into the centrifuge tube
The samples were placed into a centrifuge for about 10 minutes under 3000 rpm Optical
density was determined using spectrophotometer at wavelength of 750 nm 664 run 647
am and 630 nm Each extinctions for small turbidity blank was corrected by subtracting
750 nm from 664 nm and 630 run absorptions
The concentration of chlorophyll-a in the extract of the pigment after correction was
calculated using
Where E = the absorption in the respective wavelength
After determining the concentration of the chlorophyll-a in the extract the amount of
cblorophyll-a in the pigment per unit volume of water filtered was calculated as follows
13
Ca(v)Chlorophyll-a (Jg IL) = - shyv
Where Co = Chlorophyll-a pigment concentration in JgmL
v = Volume ofacetone in mL
v = Volume of samples in L
344 Ammonia-nitrogen (NH3-N)
For ammonia-nitrogen (NH3-N) the concentration was determined using standard
method 8038 Nessler Method (HACH 2000) A 25 mL prepared sample and 25 mL of
deionized water were filled into a separate 25 mL mixing graduated cylinder Three drops
of Mineral Stabilizer were added to both of the cylinders The cylinders were inverted
several times to mix the content After that 1 mL of Nessler reagent was pipetted into both
of the cylinders and the cylinders were inverted several times to mix the content A one-
minute reaction was started Both the solutions were poured into a square sample cell A
yellow colour formation will indicate the presence of ammonia When the timer expired
the blank was inserted into the square sample cell with the fill line facing the right The
reading at 425 run was zeroed The prepared sample was inserted into the cell holder of
Spectrophotometer DR 2800 (HACH 2000) with the fill line facing right and the reading
displayed was recorded
345 Nitrate (NO)-)
For nitrate analysis the concentration was determined using standard method 8192
Cadmium Reduction Method (HACH 2000) The sample was filled until the 15 mL mark
of a 25 mL graduated measuring cylinder The content of one Nitra Ver6 Nitrate Reagent
Pillow Powder was added into the cylinder and capped with a stopper The cylinder was
14
32 Water samples
The water samples were taken using Van Dorn water sampler at all three stations
and were taken at 6 different depths which are the subsurface (02m) 10m 20m 30m 40m
and 5Om At each station three replicates of water samples were taken back for laboratory
analysis Water samples were kept in 2 L polyethylene water bottles that has been acid
washed and were stored in cooler box filled with ice All samples were taken to the
laboratory for further analysis
33 Water quality parameters measured in-situ
Temperature dissolved oxygen (DO) pH electrical conductivity total dissolved
solids (TDS) and turbidity were taken using YSI Multiparameter Water Quality 6920 V2
The depths of each station were measured using depth finder Water transparency was also
measured using secchi disc at each station
34 Water quality parameters analysed ex-situ
341 Biochemical oxygen demand in five days (BODs)
BODs were determined by filling water samples into 300 ml BOD bottles DO
readings of the water samples were measured from the bottles All BOD bottles were
wrapped with aluminum foil to prevent light penetration and were kept in a cooler box for
5 days The initial DO value was recorded as DJ and on the 5th day the DO reading was
recorded as Ds The formula that was used for measuring BODs follows the protocol
outlined by APHA (1998)
11
BOD5 (mglL) = DJ - D5
Where DJ = Initial DO of sample immediately after preparation (mglL)
D5 = DO value after 5 days incubation at 25degC (mglL)
342 Total suspended solids (TSS)
Total suspended solids were analyzed using standard method APHA (1998) For
TSS analysis there was pre-fieldtrip sampling method and post-fieldtrip method For preshy
fieldtrip method glass fibre filter paper (GFIC 47 nun diameter 045 Ilm membrane) were
soaked in distilled water Each filter paper is placed on a piece of aluminum foil and was
dried in the oven at 103degC - 105degC overnight Filter paper then was allowed to cool for 10
minutes before weighing it using an analytical balance (ACCULAB ALC - 210) The
initial weight was recorded For post-fieldtrip method the glass fibre paper was placed on
the inter-plate of the filter funnel using a pair of forceps A known volume of water
samples was filtered using a vacuum pump After that filter paper was removed from the
filtration funnel and was placed back into the aluminum foil Filter paper was dried in the
oven at 103degC - 105degC overnight (APHA 1998) Filter paper was then taken out of the
oven and allowed to cool until room temperature before weighing The final reading of the
filtered glass fibre paper was recorded and TSS was calculated using the formula
w -wTSS (mglL) = J I
V
Where W = Initial weight of filter paper
WJ = Final weight of filter paper
V = Volume of water samples filtered (L)
12
4 Chlorophyll-a
The concentration of chlorophyll-a In the water samples were analyzed using
staDdard method APHA (1998) For chlorophyll-a analysis water samples were filtered
using vacuum pump Filter paper containing chlorophyll-a was taken from the vacuum
pump for analysis The samples were grinded by using a grinder and 5 - 6 mL of 90
acetone was added into the mortar Samples were grinded for about 5 minutes and all
materials in the mortar were placed into a capped test tube Ninety percent acetone was
added into the test tube to make up the volume to 10mL Test tube was folded with
aluminum foil and was placed in the refrigerator for 4 - 18 hours to facilitate complete
extraction of the pigments The liquid extracted was transferred into the centrifuge tube
The samples were placed into a centrifuge for about 10 minutes under 3000 rpm Optical
density was determined using spectrophotometer at wavelength of 750 nm 664 run 647
am and 630 nm Each extinctions for small turbidity blank was corrected by subtracting
750 nm from 664 nm and 630 run absorptions
The concentration of chlorophyll-a in the extract of the pigment after correction was
calculated using
Where E = the absorption in the respective wavelength
After determining the concentration of the chlorophyll-a in the extract the amount of
cblorophyll-a in the pigment per unit volume of water filtered was calculated as follows
13
Ca(v)Chlorophyll-a (Jg IL) = - shyv
Where Co = Chlorophyll-a pigment concentration in JgmL
v = Volume ofacetone in mL
v = Volume of samples in L
344 Ammonia-nitrogen (NH3-N)
For ammonia-nitrogen (NH3-N) the concentration was determined using standard
method 8038 Nessler Method (HACH 2000) A 25 mL prepared sample and 25 mL of
deionized water were filled into a separate 25 mL mixing graduated cylinder Three drops
of Mineral Stabilizer were added to both of the cylinders The cylinders were inverted
several times to mix the content After that 1 mL of Nessler reagent was pipetted into both
of the cylinders and the cylinders were inverted several times to mix the content A one-
minute reaction was started Both the solutions were poured into a square sample cell A
yellow colour formation will indicate the presence of ammonia When the timer expired
the blank was inserted into the square sample cell with the fill line facing the right The
reading at 425 run was zeroed The prepared sample was inserted into the cell holder of
Spectrophotometer DR 2800 (HACH 2000) with the fill line facing right and the reading
displayed was recorded
345 Nitrate (NO)-)
For nitrate analysis the concentration was determined using standard method 8192
Cadmium Reduction Method (HACH 2000) The sample was filled until the 15 mL mark
of a 25 mL graduated measuring cylinder The content of one Nitra Ver6 Nitrate Reagent
Pillow Powder was added into the cylinder and capped with a stopper The cylinder was
14
BOD5 (mglL) = DJ - D5
Where DJ = Initial DO of sample immediately after preparation (mglL)
D5 = DO value after 5 days incubation at 25degC (mglL)
342 Total suspended solids (TSS)
Total suspended solids were analyzed using standard method APHA (1998) For
TSS analysis there was pre-fieldtrip sampling method and post-fieldtrip method For preshy
fieldtrip method glass fibre filter paper (GFIC 47 nun diameter 045 Ilm membrane) were
soaked in distilled water Each filter paper is placed on a piece of aluminum foil and was
dried in the oven at 103degC - 105degC overnight Filter paper then was allowed to cool for 10
minutes before weighing it using an analytical balance (ACCULAB ALC - 210) The
initial weight was recorded For post-fieldtrip method the glass fibre paper was placed on
the inter-plate of the filter funnel using a pair of forceps A known volume of water
samples was filtered using a vacuum pump After that filter paper was removed from the
filtration funnel and was placed back into the aluminum foil Filter paper was dried in the
oven at 103degC - 105degC overnight (APHA 1998) Filter paper was then taken out of the
oven and allowed to cool until room temperature before weighing The final reading of the
filtered glass fibre paper was recorded and TSS was calculated using the formula
w -wTSS (mglL) = J I
V
Where W = Initial weight of filter paper
WJ = Final weight of filter paper
V = Volume of water samples filtered (L)
12
4 Chlorophyll-a
The concentration of chlorophyll-a In the water samples were analyzed using
staDdard method APHA (1998) For chlorophyll-a analysis water samples were filtered
using vacuum pump Filter paper containing chlorophyll-a was taken from the vacuum
pump for analysis The samples were grinded by using a grinder and 5 - 6 mL of 90
acetone was added into the mortar Samples were grinded for about 5 minutes and all
materials in the mortar were placed into a capped test tube Ninety percent acetone was
added into the test tube to make up the volume to 10mL Test tube was folded with
aluminum foil and was placed in the refrigerator for 4 - 18 hours to facilitate complete
extraction of the pigments The liquid extracted was transferred into the centrifuge tube
The samples were placed into a centrifuge for about 10 minutes under 3000 rpm Optical
density was determined using spectrophotometer at wavelength of 750 nm 664 run 647
am and 630 nm Each extinctions for small turbidity blank was corrected by subtracting
750 nm from 664 nm and 630 run absorptions
The concentration of chlorophyll-a in the extract of the pigment after correction was
calculated using
Where E = the absorption in the respective wavelength
After determining the concentration of the chlorophyll-a in the extract the amount of
cblorophyll-a in the pigment per unit volume of water filtered was calculated as follows
13
Ca(v)Chlorophyll-a (Jg IL) = - shyv
Where Co = Chlorophyll-a pigment concentration in JgmL
v = Volume ofacetone in mL
v = Volume of samples in L
344 Ammonia-nitrogen (NH3-N)
For ammonia-nitrogen (NH3-N) the concentration was determined using standard
method 8038 Nessler Method (HACH 2000) A 25 mL prepared sample and 25 mL of
deionized water were filled into a separate 25 mL mixing graduated cylinder Three drops
of Mineral Stabilizer were added to both of the cylinders The cylinders were inverted
several times to mix the content After that 1 mL of Nessler reagent was pipetted into both
of the cylinders and the cylinders were inverted several times to mix the content A one-
minute reaction was started Both the solutions were poured into a square sample cell A
yellow colour formation will indicate the presence of ammonia When the timer expired
the blank was inserted into the square sample cell with the fill line facing the right The
reading at 425 run was zeroed The prepared sample was inserted into the cell holder of
Spectrophotometer DR 2800 (HACH 2000) with the fill line facing right and the reading
displayed was recorded
345 Nitrate (NO)-)
For nitrate analysis the concentration was determined using standard method 8192
Cadmium Reduction Method (HACH 2000) The sample was filled until the 15 mL mark
of a 25 mL graduated measuring cylinder The content of one Nitra Ver6 Nitrate Reagent
Pillow Powder was added into the cylinder and capped with a stopper The cylinder was
14
4 Chlorophyll-a
The concentration of chlorophyll-a In the water samples were analyzed using
staDdard method APHA (1998) For chlorophyll-a analysis water samples were filtered
using vacuum pump Filter paper containing chlorophyll-a was taken from the vacuum
pump for analysis The samples were grinded by using a grinder and 5 - 6 mL of 90
acetone was added into the mortar Samples were grinded for about 5 minutes and all
materials in the mortar were placed into a capped test tube Ninety percent acetone was
added into the test tube to make up the volume to 10mL Test tube was folded with
aluminum foil and was placed in the refrigerator for 4 - 18 hours to facilitate complete
extraction of the pigments The liquid extracted was transferred into the centrifuge tube
The samples were placed into a centrifuge for about 10 minutes under 3000 rpm Optical
density was determined using spectrophotometer at wavelength of 750 nm 664 run 647
am and 630 nm Each extinctions for small turbidity blank was corrected by subtracting
750 nm from 664 nm and 630 run absorptions
The concentration of chlorophyll-a in the extract of the pigment after correction was
calculated using
Where E = the absorption in the respective wavelength
After determining the concentration of the chlorophyll-a in the extract the amount of
cblorophyll-a in the pigment per unit volume of water filtered was calculated as follows
13
Ca(v)Chlorophyll-a (Jg IL) = - shyv
Where Co = Chlorophyll-a pigment concentration in JgmL
v = Volume ofacetone in mL
v = Volume of samples in L
344 Ammonia-nitrogen (NH3-N)
For ammonia-nitrogen (NH3-N) the concentration was determined using standard
method 8038 Nessler Method (HACH 2000) A 25 mL prepared sample and 25 mL of
deionized water were filled into a separate 25 mL mixing graduated cylinder Three drops
of Mineral Stabilizer were added to both of the cylinders The cylinders were inverted
several times to mix the content After that 1 mL of Nessler reagent was pipetted into both
of the cylinders and the cylinders were inverted several times to mix the content A one-
minute reaction was started Both the solutions were poured into a square sample cell A
yellow colour formation will indicate the presence of ammonia When the timer expired
the blank was inserted into the square sample cell with the fill line facing the right The
reading at 425 run was zeroed The prepared sample was inserted into the cell holder of
Spectrophotometer DR 2800 (HACH 2000) with the fill line facing right and the reading
displayed was recorded
345 Nitrate (NO)-)
For nitrate analysis the concentration was determined using standard method 8192
Cadmium Reduction Method (HACH 2000) The sample was filled until the 15 mL mark
of a 25 mL graduated measuring cylinder The content of one Nitra Ver6 Nitrate Reagent
Pillow Powder was added into the cylinder and capped with a stopper The cylinder was
14
Ca(v)Chlorophyll-a (Jg IL) = - shyv
Where Co = Chlorophyll-a pigment concentration in JgmL
v = Volume ofacetone in mL
v = Volume of samples in L
344 Ammonia-nitrogen (NH3-N)
For ammonia-nitrogen (NH3-N) the concentration was determined using standard
method 8038 Nessler Method (HACH 2000) A 25 mL prepared sample and 25 mL of
deionized water were filled into a separate 25 mL mixing graduated cylinder Three drops
of Mineral Stabilizer were added to both of the cylinders The cylinders were inverted
several times to mix the content After that 1 mL of Nessler reagent was pipetted into both
of the cylinders and the cylinders were inverted several times to mix the content A one-
minute reaction was started Both the solutions were poured into a square sample cell A
yellow colour formation will indicate the presence of ammonia When the timer expired
the blank was inserted into the square sample cell with the fill line facing the right The
reading at 425 run was zeroed The prepared sample was inserted into the cell holder of
Spectrophotometer DR 2800 (HACH 2000) with the fill line facing right and the reading
displayed was recorded
345 Nitrate (NO)-)
For nitrate analysis the concentration was determined using standard method 8192
Cadmium Reduction Method (HACH 2000) The sample was filled until the 15 mL mark
of a 25 mL graduated measuring cylinder The content of one Nitra Ver6 Nitrate Reagent
Pillow Powder was added into the cylinder and capped with a stopper The cylinder was
14
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