Study and Assessment of an Eutrophied Inland Water body

8/10/2019 Study and Assessment of an Eutrophied Inland Water body

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CHAPTER 1

INTRODUCTION

1.1 GENERAL

As we plunge into a new century and a new millennium, the environment is being

called on to supply the growing needs of an expanding human population in the

developing countries and increasing affluence in the developed countries. In many areas

we are already taking more from the earths systems than they can provide in a

sustainable fashion. Environmental pollution means the presence in the environment of

any environmental pollutant. Environmental pollutant means any solid, liquid or gaseous

substance present in such concentration as may be, or tend to be, inurious to

environment.

!ater is a maor constituent of all living organisms. "ver #$% of the Earths

surface is covered by water. !ithout water, life on Earth would be impossible. It is

essential for everything on our planet to grow and prosper. Although we as humans

recogni&e this fact, we disregard it by polluting our rivers, lakes, and oceans.

'ubsequently, we are slowly but surely harming our planet to the point where organisms

are dying at a very alarming rate. As per the !ater ()revention and *ontrol of )ollution+

Act, -#, pollution means such concentration of water or such alteration of the physical,

chemical and biological properties of water or such discharge of any sewage or trade

effluent or any other liquid, gaseous or solid substance into water (whether directly or

indirectly+ as may, or likely to, create or nuisance or render such water harmful or

inurious to public health safety or to domestic, commercial, industrial, agricultural or

other legitimate uses, or to the life and health of animals or plants or of aquatic

organisms.

1.2 WATER POLLUTION

!ater typically referred to as polluted when it is impaired by anthropogenic

contaminants and either support a human use or undergoes a marked shift in its ability to


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support its constituent biotic communities. It is being polluted due to over population in

terms of sewage and garbage, agricultural development in terms of pesticide and fertili&er

application and rapid industriali&ation in terms of effluent and ha&ardous waste. In India,

the main culprits for the degradation of water bodies are sewage and garbage generated

especially in the urban areas. Absence of sewage treatment plant and garbage treatment

leads to discharge of untreated sewage and garbage into water bodies. In /erala, water

bodies are polluted due to sewage and garbage. !astes generated within households are

often disposed of in nearby drains. 0ubbish like plastic, glass is dumped into canals and

rivers. Industries discharge wastes directly into water bodies leading to death of aquatic

organisms due to the decrease in oxygen in water and due to reduction in p1. 'ome

stretch of rivers and lakes namely )eriyar are affected due to industrial effluent.

'ewage, manure and chemical fertili&ers contain nutrients such as nitrate and

phosphate and when it enters water body in excess levels, nutrients over stimulate the

growth of aquatic plants and algae. Excessive growth of these organisms clogs our water

ways and blocks light to deeper waters. !hen the organisms die, they use up dissolved

oxygen as they decompose causing depletion of oxygen in water. 'ewage contains

pathogens which cause diseases such as cholera, diarrhoea, typhoid and skin diseases.

)athogens include such organisms as bacteria, virus and proto&oan. 'tagnated water

bodies are breeding grounds for mosquitoes causing dreadful diseases like chikunguinea,

malaria. )olluted water kills fish, vegetation and other aquatic organisms. !eeds make

waterways impassable. !hen a lot of soil is washed into rivers and drains, this causes

aquatic life to perish and floods especially with heavy rainfall.

1.3 LAKE POLLUTION

2he lakes are vital ecosystems deserving utmost care. Increasing population

pressure and the resultant socio3economic development around this water bodies result in

the deterioration of water quality. 2he problems faced by the lake systems can be

generali&ed as + eutrophication 4+ siltation 5+ shrinkage in water spread + reclamation

6+ encroachments 7+ pollution resulting from natural as well as anthropogenic activities

#+ excessive tourism load 8+ over fishing98:. Eutrophication means excessive plant growth

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in lakes, estuaries and slow moving streams due to excess nutrients mainly from sewage

and agricultural runoff. Excessive weed growth leads to high rate of siltation and results

in shoaling of the lake. 2he shrinkage in lake water spread is mainly due to reclamation

and rooted weed growth. !hen sediments enter water bodies, fish respiration becomes

impaired, plant productivity and water depth become reduced and aquatic organisms and

their environment become suffocated98:.

1.4 WATER QUALITY INDEX

!ater quality monitoring data consists of routine measurements of physical, chemical

and biological variables that are intended to give insight into the aquatic environment.

2he !;I serves as a tool, to examine the trends, to highlight specific water quality

conditions, and help governmental organi&ations to evaluate the effectiveness or

regulatory programs. In essence, !;I has following important purposes.

. 2rend Analysis< Index may be applied to water quality data at different points in

time to determine the changes in water quality (degradation or improvement+

which have occurred over the period.

4. )ublic Information< Index may be used to inform the public about environmental

conditions.

5. 0anking and 0ationali&ation of locations< Index may be applied to assist in

comparing environmental conditions at different locations of geographic areas.

. 'cientific 0esearch< Index may be applied as a means of reducing a large quantity

of data to form that give insights to the researcher conducting a study of some

water quality processes.

1.5 EUTROPHICATION

Eutrophication is a process whereby water bodies, such as lakes, estuaries, or

slow3moving streams receive excess nutrients that stimulate excessive plant growth

(algae, periphyton attached algae, and nuisance plants weeds+. 2his enhanced plant

growth, often called an algal bloom, reduces dissolved oxygen in the water when dead

plant material decomposes and can cause other organisms to die. =utrients can come

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from many sources, such as discharge of untreated sewage, fertili&ers applied to

agricultural fields, golf courses and suburban lawns> deposition of nitrogen from the

atmosphere and erosion of soil containing nutrients. !ater with a low concentration of

dissolved oxygen is called hypoxic. Eutrophication is caused by the increase of an

ecosystem with chemical nutrients, typically compounds containing nitrogen or

phosphorus. It may occur on land or in the water97:. Eutrophication is frequently a result

of nutrient pollution such as the release of sewage effluent into natural waters (rivers or

coasts+ although it may occur naturally in situations where nutrients accumulate (e.g.

depositional environments+ or where they flow into systems on an ephemeral basis (e.g.

intermittent upwelling in coastal systems+. Estuaries tend to be naturally Eutrophic

because land3derived nutrients are concentrated where run3off enters the marine

environment in a confined channel and mixing of relatively high nutrient fresh water with

low nutrient marine water occurs.

2he names of the four trophic states, from the lowest level of biological

productivity to the highest, are listed below ('ource< http


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2otal nitrogen is less than $$C g?D

!ater clarity is greater than 5 feet

4. $%&oto!"i#

@esotrophic water bodies have a moderate level of biological productivity.

@esomeans mid3range.B

*riteria< 2otal chlorophyll is between 5 and # C g?D

2otal phosphorus is between 6 and 46 C g?D

2otal nitrogen is between $$ and 7$$ C g?D

!ater clarity is between 8 and 5 feet

5. E'to!"i#

Eutrophicwater bodies have a high level of biological productivity.

Eumeans good or sufficient.B

*riteria< 2otal chlorophyll is between # and $ C g?D

2otal phosphorus is between 46 and $$ C g?D

2otal nitrogen is between 7$$ and 6$$ C g?D

!ater clarity is between 5 and 8 feet

.H(!%%'to!"i#

1ypereutrophic water bodies have the highest level of biological productivity.

1yper means over abundant.B

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*riteria< 2otal chlorophyll is greater than $ C g?D

2otal phosphorus is greater than $$ C g?D

2otal nitrogen is greater than 6$$ C g?D

!ater clarity is less than 5 feet

!ater hyacinth 9Eichhornia crassipes:, a native of Ama&on riverbasin in 'outh

America is a troublesomeaquatic weed all over the world. It was introduced into India in8-7 as an ornamentalpond plant. =ow this weed isseen infesting more than 4$$,$$$ ha

ofwater surface, causing concern in -8 out of 47 districts in India. 2his fast multiplying

weed can produce 5$$$ offspringin 6$ days and can double its biomass in$4 days.

2he disadvantages of this weed outweigh its merits. It interferes with production of

hydroelectricity, blocks water flow in irrigation and drainage canals, channels and

streams leading to flooding and seepage into adoining areas, hinders anti3mosquito

operations and forms a breeding ground for obnoxious insects like mosquitoes which

transmit infectious diseases such as malaria and encephalomyelitis. It also affects the

aquatic fauna through elimination of habitat and depletion of oxygen level caused by

respiration and decomposition of vegetative parts. 2he excessive weed population is

strong enough to stop boats or slow down navigation. It also makes recreational water

activity difficult and unsafe inlakes.

Algae play an important role in the limnology and ecology. Algae are the

predominant photo synthesi&ers of fresh water and all aquatic environments. 2he density

and distribution of phytoplanktons are determined by the variability and distribution of

nutrients in an aquatic system. *ertain selected types of algae also are used as indicators

of pollution96:.

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1.) CARL*ON+* TROPHIC *TATE INDEX

2he cloudiness of lake water is often related to the amount of nutrients in the

water. =utrients promote growth of microscopic plant cells (phytoplankton+ that are fed

upon by microscopic animals (&ooplankton+. 2he more the nutrients, the more the plants

and animals and the cloudier the water is. 2his is a common, but indirect, way to roughly

estimate the condition of the lake. 2his condition, called eutrophication, is a natural aging

process of lakes, but which is unnaturally accelerated by too many nutrients. 2rophic

state is defined as the total weight of living biological material (biomass+ in a waterbody

at a specific location and time. Algal biomass is used as the basis for trophic state

classification. *hlorphyll pigments, secchi depth and total phosphorous independently

examines algal biomass.

A 'ecchi disk is commonly used to measure the depth to which you can easily see

through the water, also called its transparency. 'ecchi disk transparency, chlorophyll a

(an indirect measure of phytoplankton+, and total phosphorus (an important nutrient and

potential pollutant+ are often used to define the degree of eutrophication, or trophic status

of a lake. 2he concept of trophic status is based on the fact that changes in nutrient levels

(measured by total phosphorus+ causes changes in algal biomass (measured by

chlorophyll a+ which in turn causes changes in lake clarity (measured by 'ecchi disk

transparency+. A trophic state index is a convenient way to quantify this relationship.

*arlsons index is a popular index and was developed by Fr. 0obert *arlsonof /ent

'tate Gniversity.

1., WATER QUALITY $ONITORING

!ater quality monitoring gives an idea about the status of water quality and extent

of deterioration caused. !ater quality results comprise of concentration of various water

quality parameters at different stations and hence it is very complex. Analysis of water

quality data is essential for arriving at a useful conclusion. Analysis of water quality data

is indeed a necessary extension to monitoring of water quality. 'tatistical analysis

converts the water quality data into something deductive by providing useful implications

#
http://bioweb.biology.kent.edu/FacultyandStaff/carlson.htmlhttp://bioweb.biology.kent.edu/FacultyandStaff/carlson.html


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not so obvious from the raw data. *orrelation, regression and factor analysis help in

developing and interpreting relationship between water quality parameters and

rationali&ing monitoring network. Fetection of trend and violations provide a useful

insight into the spatial temporal behaviors or water quality data so as to plan appropriate

pollution control measures. 2he water quality parameters analy&ed in the laboratory are

given below9$:.

!H

p1 is negative logarithm of hydrogen ion concentration. Hresh sewage is

generally alkaline in nature. As time passes, p1 tends to fall due to production of acids by

bacterial action in anaerobic or nitrification processes.

T'-iit(

'uspension of particles in water interfering with passage of light is called turbidity.

2urbidity is caused by a wide variety of suspended materials, which range in si&e from

colloidal to coarse dispersions.

El%#ti#/l Co0'#tiit(

Electrical conductivity is the capacity of water to carry an electrical current. It

depends on the presence of ions and its concentration. 'olutions of most inorganic acids,

bases and salts are relatively good conductors of electricity. @olecules of organic

compounds that do not dissociate in aqueous solution is a poor conductor of electricity.

@ost dissolved inorganic substance contributes to conductance.

Tot/l Di&&ol% *oli&

'olids present in water as suspended solids, colloidal solids, settleable solids and

dissolved solids. 2otal dissolved solids are those solids which remain dissolved in water.

enerally carbonates, bicarbonates, chlorides, nitrates and sulphate of sodium, potassium,

calcium and magnesium contribute total solids in water.

*'&!%0% *oli&

'uspended solids are those which remain floating in water.

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Di&&ol% O(g%0

2he oxygen dissolved in surface water is largely derived from the atmosphere and

from the photosynthetic activity of algae and higher aquatic plants. *oncentration of

dissolved oxygen will vary daily and seasonally and depend on the species of

phytoplankton present, light penetration, nutrient availability, temperature, salinity, water

movement, partial pressure of atmospheric oxygen in contact with the water, thickness of

the surface film and biodepletion rates. !hen oxygen depleting substances from sewage

enter water, the self purification capacity of water is affected and the dissolved oxygen

concentration decreases to the point of complete disappearance of oxygen from water.

2his condition results in sign of eutrophication with the growth of algal blooms.

io#"%i#/l O(g%0 D%/0 OD6

2here are two types of organic matter.

a. biologically oxidi&ed (oxidi&ed by bacteria+

b. can not be biologically oxidi&ed (biologically inactive+

Jiochemical "xygen Femand gives the biologically active organic matter present in

water. @icro3organisms utili&e the atmospheric oxygen dissolved in the water for

biochemical oxidation of polluting matter, which is their source of carbon. It is a

measure of organic matter present in a water sample and can be defined as the amount of

oxygen required by the micro3organism in stabili&ing the biologically degradable organic

matter under aerobic condition.

Ao0i/#/l Nitog%0

Ammoniacal nitrogen indicates the very first stage of decomposition of organic

matter. Ammonia is formed by the deamination of organic nitrogen containing

compounds and by the hydrolysis of urea. Ammonia is readily available as a nutrient for

plant uptake and this may contribute greatly to increased biological productivity. It is

easily oxidi&ed to nitrite and nitrate in the presence of sufficient oxygen (nitrification+.

Gnder anaerobic condition, organic nitrogen is converted into ioni&ed (=1K+ and

unioni&ed (1=5+ ammonia.

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Nitit% Nitog%0

=itrite is formed in water by oxidation of ammonium compounds or by reduction

of nitrate. As an intermediate stage in the nitrogen cycle, it is unstable. =itrite indicates

the presence of partly decomposed organic matter in water. It is the intermediate stage of

conversion of organic matter into stable forms.

Nit/t% Nitog%0

=itrate is the most highly oxidi&ed form of nitrogen compounds. It is the end

product of the aerobic decomposition of organic nitrogenous matter. 2he sources of

nitrate are chemical fertili&ers from cultivated land> drainage from livestock feed lots as

well as domestic and some industrial water. =itrates indicate the presence of fully

oxidi&ed organic matter.

*'l!"/t%

'ulphates are formed due to the decomposition of sulphur containing compounds.

!hen oxygen level falls to &ero (anaerobic &one+, some bacteria derive oxygen through

reduction of nitrates. "n complete exhaustion of nitrate, oxygen may be obtained by

reduction of sulphate yielding hydrogen sulphide causing foul smell and putrefied taste

for water.

P"o&!"/t%

)hosphorous compounds are carried into natural waters with waste waters and

storm runoff. 2hey may produce a secondary pollution, being essential nutrients. Algal

blooms occur where both nitrogen and phosphorous are plentiful. 'ewage is relatively

rich in phosphorous compounds. @ost of the inorganic phosphorous was contributed by

human wastes as a result of the metabolic breakdown of proteins and elimination of the

liberated phosphates in the urine. 2he use of polyphosphate in detergents increases the

phosphorous content of domestic sewage. 2he amount of phosphorous released is a

function of protein intake.

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C"loi%

*hloride ion is generally present in natural waters. A high concentration occurs in

waters from chloride containing geological formations. "therwise, high chloride content

may indicate pollution by sewage or some industrial wastes or an intrusion of sea water

or other saline water. 1uman excreta, particularly the urine, contain chloride in an

amount equal to chloride consumed with food and water.

Tot/l H/0%&&

1ardness is caused by divalent metallic cations. 2he principal hardness causing

cations are calcium, magnesium, strontium, ferrous iron and manganous ions. 2he anions

responsible for hardness are mainly bicarbonates, carbonates, sulphate, chloride, nitrate,

silicates etc.

Tot/l Coli7o

2otal *oliform is an indicator of pollution due to sewage.

8/%#/l Coli7o

Haecal coliform indicates the presence of faecal pollution. It is an indicator of

faecal contamination.

1.9 GEOGRAPHICAL IN8OR$ATION *Y*TE$

2he technology of eographic Information system (I'+ facilitates the

organi&ation and management of data with a geographic component. eographic

Information 'ystem is an organi&ed collection of hardware, software, geographic data and

personnel designed to efficiently capture, store, update, manipulate and display all forms

of geographically referenced information. A geographic information system (I'+ is a

computer system for capturing, storing, querying, analy&ing and displaying

geographically referenced data. 2he ability of a I' to handle and process geographically

referenced data distinguishes I' from other information system.


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I' packages differ according to the data structure they use to store the data. 2he

way in which the spatial data are structured for storing the data will determine how the

user can retrieve, analy&e and do modeling. 2he often used data models for spatial data

are raster and vector. A raster model divides the entire study area into regular grid of

cells, organi&ed into rows and columns. 2he vector model is that all geographic features

in a real world (or on a map+ can be represented as points, lines (arcs+ or areas(polygon+.

In this model, the spatial locations of features are defined on the basis of coordinate pairs.

A vector model represents more accurately, then features without any blocky appearance

and allows complex data to be stored in a minimum space. A point has no dimension.

Jesides the (x, y+ coordinates, other data must be stored to indicate what kind of point it

is and other information if any associated with it. Dines requires a minimum of two (x, y+

coordinates (straight line+ to define a line. )olygons are represented by listing coordinates

of points around the boundary of the polygon. 2he beginning and end are the same point

thus making a closed area9-:.

A I' typically made up of a variety of information systems like Artographic

Fisplay 'ystem, @ap Figiti&ing 'ystem, database @anagement 'ystem, eographic

Analysis 'ystem, Image )rocessing 'ystem, 'tatistical Analysis 'ystem and Fecision

'upport system.

8ig 1.1 GI* /0 R%l/t% Dii!li0%

2he most common method of structuring the geography of the real world in the

computer is to use a layered approach. Each layer is thematic and reflects either a

particular use or the characteristic of the landscape. In I', there are two types of data to

be managed< spatial data and attribute data. An entity (point, line or area+ has both spatial

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(where things are+ and attribute (what things are+ data to describe it. Fatabase offer more

than ust a method of handling the attributes of spatial entities> they can help to convert

into information with value9-:.

I' carries out the integrated analysis, so as to spatially combine multiple

features to generate a composite theme. Fata collection and digiti&ing?editing (to be

compatible for computer storage+ are the most time3consuming activity. Lisually

interpreted thematic maps and topographical maps need to be digiti&ed96:.

I' links spatial data with the geographical information about a particular feature

on a map. 2he information is stored as attributes of the geographically represented

feature. I' technology integrates common database operations such as query and

statistical analysis with the unique visuali&ation and benefits of geographic analysis that

is offered by the maps 95:. 2he visual presentation of results of water quality monitoring

helps us to give a clear picture of quality of surface water at a glance using I'. 2he

complex relationship between various parameters can be easily studied if the water

quality results are presented in a visually appealing manner as a map rather than a set of

rows and columns of figures. 2he spatial distribution of water contaminants and other

water quality parameters can be displayed in an effective manner. 2his helps authorities

in taking effective measures to check water pollution and thereby to restore water quality.

1.: *TUDY AREA

2he Akkulam3 Leli Dake and their surrounding areas have become a region of

tourist attraction in recent years. It is situated approximately 6 km north3west of

2hiruvananthapuram between latitudes 846 and 856 = and longitudes #76$ and

#768 E and the lake is having an area of less than km 4 surrounded by lateritic hillocks.

'erious environmental degradation is being experienced by this system due to sewage

and the municipal solid waste generated in the *ity, eutrophication problem,

developmental activities, etc. Dack of flushing results in the piling up of the pollutants.

2he lake is partially separated into two by the existence of a bund across the lake. 2he

western part of the lake having a length of .46 km with an average width of $$ m is the

Leli /ayal. 2he =orth Eastern part starting from the bund forms the Akkulam part of the

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lake. Hor most part of the year these lakes remain separated from the sea by a sand bar

which is approximately 6$ m and having a width of 4$3$ m. 2he )o&hi remains open

usually for a period of $3 days depending upon the influx of land drainage to the lake.

Gsually this episode repeats 738 times a year. 2he weeds which had a prolific growth

while the lake had a near fresh water condition are seen dying as they are intolerant to

saline water98:.

2wo canals, vi&. the /ulathur *anal and )arvathy )uthen Ar (*hannankara *anal+

oin the Leli Dake in the northern side. 2he *hakka *anal, also called as the )arvathy

)uthen Ar connects Leli kayal with the )oonthura kayal in the south. 'eepage of sewage

from @uttathara 'ewage Harm makes the canal water extremely polluted. /annammoola

2hodu oins the eastern part of the Akkulam Dake. 'ewage from the 2hiruvananthapuram

*ity and drainage from the suburbs are brought into the lake through the /annammoola

2hodu. 2he /ulathur canal brings in substantial quantities of fresh water to lake during

the southwest and northeast monsoon. 2he Leli lake is connected to the Akkulam lake by

a narrow channel. English India *lay Dtd is situated in southern bank of the Leli lake.

2here is chance of entry of effluent from 2ravancore 2itanium )roducts through sea

during the period of connection of lake with the sea. 2he lake is an excellent inland water

navigational tract and /erala 2ourism Fevelopment *orporation has developed Akkulam

and Leli boat club on its banks as maor tourist attraction. 2his is also responsible for

man3made changes in the quality of water in the lake94:.

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2he obectives of the study are the eventual consequence of that enrichment is the growth of primary

production to nuisance proportions. As per Mana et. al. (--6+, the main cause of

eutrophication is excessive loading into the system of phosphorous and nitrogen,

resulting in high algal biomass, dominance by cyanobacteria and loss of macrophyte.

According to Lollenweider (-#7+, the concept of nutrient overloading has a great impact

on all subsequent eutrophication research and lake management. Eutrophication is

accelerated as a result of human activities near or in a body of water that generate

residential wastes, untreated or partially treated sewage, agricultural runoff, urban

pollutants and so forth. 'ewage or residential waste, consisting largely of phosphate

containing detergents, is a maor source of nutrients in water bodies. 2he G. '.

Environmental )rotection Agency (-#7+ suggested that for phosphate, $.$8 ppm was the

critical level for the occurrence of eutrophication in lakes and reservoirs. 2he flow of

nutrients in the water may over stimulate the growth of algae. 2his creates conditions

that interfere with the recreational use of lakes and adversely affect the diversity of

indigenous fish, plant and animal populations.

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Dathrop (-88+ studied present trends in the summer levels of phosphorous,

chlorophyll and water clarity in the Nahare lake from -#73-88. 2hese three interrelated

parameters are indices of lake trophic state (degree to fertility+. )hosphorous is generally

the nutrient causing lake eutrophication. *hlorophyll3a, the primary photosynthetic

pigment, is a direct measure of algal biomass, 'ecchi disk transparency readings

represent an easily understood measure of the water quality of the lake of how Ogreen the

lakes are perceived.

'avita et. al. (4$$6+ conducted study on nutrient overloading of 'hahpura lake, a

fresh water lake of Jhopal. 1igh phosphate content in the lake water revealed that

nutrient load in the lake was very high and hyper eutrophic conditions were prevailing.

2he phosphate concentration in the water is very high as compared to the standard

guidelines. 2his condition was accompanied by a gradual filling up of the water body,

which became shallower from the accumulation of plants and sediments on the bottom

and also became smaller due to the invasion of shore vegetation. 2he extinction of the

lake can result because of enrichment, productivity, decay and sedimentation.

Nateesh /andi.et.al reports that water quality in inland lakes is often described in

terms of tropic state (nutritional state+. A lake with increased growth of phytoplankton is

called a Eutrophic DakeB. 2he main reason for eutrophication in most lakes is

phosphorus loading. Jecause the different broad classes of algae have somewhat different

spectral response patterns, aerial and space imaging can distinguish them. Jy spectral

response, we mean the response of an obect to the incident wavelength upon it. Each

obect responds differently to the different wavelengths. 2his is described by its unique

response called 'pectral 'ignature. 2he data collected from various sources (Aerial

)hotographs, 'atellite Images, Hield 'urveys and stored databases+ will be integrated and

analy&ed in a I' to provide useful spatial information and temporal changes over large

geographic areas affecting the structure and function of lakes.

'heela (4$$7+ conducted study on the downstream stretch of the river /aramana.

samples from this stretch starting from 2hiruvallom were collected and analy&ed. 2he

variation in water quality with respect to each 8 water quality parameters was shown on

a map using the monitoring results with the help of /irging method in the geostatistical

tool. Lariation in water quality index in the stretch was also presented using I'. 2his

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will assist the concerned authority in analy&ing the spatial distribution of OEutrophication

level in a lake. 2his will help them in taking decisions regarding Ousage of lake for

different purposes and also take countermeasures to Ocontrol pollution level of the water

bodies.

0obert E. *arlson developed a numerical trophic state index for lakes that

incorporates most lakes in a scale of $ to $$. Each maor division ($, 4$, 5$, etc.+

represents a doubling in algal biomass. 2he index number can be calculated from any of

several parameters, including 'ecchi disk transparency, chlorophyll, and total

phosphorus.

/. @uni&, A. studied a dataset comprising 4 oceanographic cruises (from -#-

to -85+, covering two regions inthe =orthwestern @editerranean 'ea (ulf of Dyon and

*atalan 'ea+, was statistically analy&ed for nitrate and phosphate relationships with

silicate, salinity and depth. 2his analysis provided a preliminary assessment of the datas

quality, as well as a predictor model of these nutrients below the surface layer. 0esults

from the statistical analysis showed no significant difference () P $.$6+, between the

regression equations (nitrate3depth and phosphate3salinity+ of most cruises in the ulf of

Dyon, indicating that these relationships do not change in this area, particularly in

summer and autumn. A significant relationship between nitrate and phosphate with

salinity and depth (multiple regressions+ was observed, suggesting that nitrate and

phosphate distribution in the intermediate level are significantly related to the mixture of

the water masses and the degradation of organic matter. 2he phosphate data showed a

wide variance and a bias, probably due to procedural problems in the chemical analysis.

Jelow the Intermediate Devantine !ater, results from the A="LA showed no significant

variation of the phosphate and nitrate concentrations in the water column. 1owever, a

spatial and temporal variation was observed in this level.

'unil '. 'haha et.al characteri&ed lakes as dynamic ecosystems that reflect their

specific characteristics, variations in climate, and biological components. 2he si&e of the

lake basin, its depth and volume, the si&e of the watershed and the quantity and quality of

water that enters the lake are important considerations. Dake management activities are

implemented on the basis of this information, including surface use regulations, aeration,

native and exotic aquatic plant management. Dake management issues related to the

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physical characteristics of the lake will require data on the surface area, shape, depth and

volume of the lake. 2he inlet and outlet characteristics and bottom types are also

important. A detailed study and proect reports are prepared for conservation and revival

of 0ankala Dake at /olhapur, @ahalaxmi Dake at Ladagaon and @ansi anga Dake at

ovardhan. 2he general methodology included 0econnaissance survey of lake and its

catchments, detailed survey of the lake area, gathering present and historical information.

2he obective is to emulate a natural, self3regulating system that is integrated ecologically

with the landscape in which it occurs. @anagement towards this end should emphasi&e

the long3term sustenance of historical and natural functions as well as values. 2he

preliminary step that is proposed in restoring lake for their long3term sustenance.

@uraleedharan =air et.al.(--8+ conducted various physical and chemical studies

in the water and sediment quality parameters and concluded that for most part of the year,

the lake as a whole is in a highly degraded state. 2he study revealed that the chief

sources of pollutants to this lacustrine system are from the municipal and domestic

sewage and untreated or partially treated industrial effluent discharged in to the system.

Dack of natural flushing, elevated values of nutrient content and near3fresh water

conditions of the lake aids in the prolific growth of aquatic weeds, especially the water

hyacinth. It was recommended to take coordinated approach for salvaging and sustaining

this lake system by involving planners, scientists, environmentalists, technocrats and

administrators.

CHAPTER 3

$ETHODOLOGY

-


20/73

3.1 GENERAL

2he knowledge on the physico3chemical parameters of a lacustrine system is of

great importance while attempting to characteri&e its general features, distribution pattern

of various pollutants, salinity intrusion, abundance of nutrients, etc. Its essential to

analy&e various sediment and water quality parameters to assess the health of a lacustrine

system. 1ydrographic features such as temperature, p1, dissolved oxygen (F"+,

biochemical oxygen demand (J"F+, salinity, nutrients, etc., of the lake are greatly

influenced by topographic, climatic and anthropogenic factors. 'ediments act as sinks to

various pollutants introduced into the water body.

3.2 WATER QUALITY ANALY*I*

2he study area, Akkulam lake is situated in 2hiruvananthapuram Fistrict of

/erala, India. Hor the present investigation to study the degradation of the lake, six sets of

samples from Hebruary to Muly 4$$8 were collected from ten selected locations. !ater

samples were collected with utmost care. As far as possible samples were taken from the

same place at the same time of the day. !ater samples were collected in sterili&ed plastic

bottles. 2he collections were made during the day time. 2he temperature of the water

samples were examined at the spot by means of a good grade *elsius thermometer.

@aximum care was taken for the collection of samples, their preservation and storage as

per the A)1A standards. 2he physico3chemical characteristics of the water samples were

analy&ed using the standard methods (A)1A. et al., --6+. 2he parameters analy&ed are

p1, Electrical conductivity, 2urbidity, 'ecchi Fistance, *hemical "xygen Femand,

'uspended solids, 2otal dissolved solids, Fissolved "xygen, Jiological oxygen demand,

Ammoniacal =itrogen, =itrite, =itrate, 'ulphate, )hosphate, 2otal )hosphorous,

*hlorophyll (may+, *hloride, 2otal *oliform and Hecal *oliform.

3.3 *EDI$ENT ANALY*I*

4$


21/73

'edimentation is a spontaneous natural process and the analysis of the sediments has

greater attention in the world due to the growing awareness of environmental pollution

and its impact on the ecosystem. Hour sampling stations were selected for investigation.

'ediments were scooped up from the sampling locations by using a Lan Leen rab. A

part of the sediment samples was oven dried at $$ $6 * overnight and finely

powdered. 2he organic carbon content of the sediment was estimated by the method of

El3!akeel and 0iley(-6#+. 2he p1 and conductivity of the sediment samples were

determined using the p1 meter and conductivity meter. 2extural Analysis of the sediment

samples was done using the !et sieving and )ipette method.

3.4 DI*PLAY WATER QUALITY INDEX

!ater quality index serves as a tool to examine trends, to highlight specific water

quality conditions. =ational 'anitation Houndation !ater ;uality Index (='H !;I+ is

used for the study.

T/-l% 3.1 E>'/tio0& 7o W/t% Q'/lit( P//%t%& N*8 WQI6

W/t% Q'/lit(

P//%t%

R/0g%

A!!li#/-l%

E>'/tio0 Co%l/tio0

Co%77i#i%0t

)ercentage 'aturation

F"

$ $% F"QP $.8K$.77x(% saturation

F"+

$.--

$ $$% F"QP 35.6K.#x(% saturation

F"+

$.--

$$ $% F"QP 75.53$.74x(% saturation

F"+

3$.--

J"F(mg?D+ $ $ J"FQP -7.7#3#.$$x(J"F+ 3$.--

$ 5$ J"FQP 58.-$3.45x(J"F+ 3$.-6

p1 4 6 p1QP 7.$K #.56x (p1+ $.-46

6 #.5 p1QP 34.7#3 55.6x (p1+ $.--

#.5 $ p1QP 57.-73 4-.86x (p1+ 3$.-8

$ 4 p1QP -7.#3 8.$$x (p1+ 3$.-5

Hecal*oliforms(=o?$$mD+

$5 *oliQP -#.4$347.8$xlog(H*+ 3$.--$53$6 *oliQP 4.553#.#6xlog(H*+ 3$.-8

$6 *oliQP 4 3

('ource< !ater ;uality Analysis 'tatistical *)*J +

4


22/73

It has been calculated on the basis of water quality parameters namely dissolved oxygen,

fecal coliforms, p1 and J"F. In order to facilitate easy computation of the sub indices,

mathematical equations could be fitted. 2able 5. lists the regression equations for the

four water quality parameters of concern. 2he variation of ='H !;I can be shown in a

map as mentioned above. 2he variation can be described on the basis of the following

descriptor words suggested for reporting the ='H!;I.

T/-l% 3.2 D%i!to ?o& 7o %!oti0g N*8 WQI

N*8 WQI D%i!to ?o&

$346 Lery bad

4736$ Jad

63#$ @edium

#3-$ good-3$$ Excellent

('ource< !ater ;uality Analysis 'tatistical *)*J +

3.5 CREATING THE$ATIC $AP* U*ING GI*

I' is a tool, which will help the designers for storing and retrieving the required

information with ease and work in a systematic manner. 'patial data is obtained from

topological maps of the study area (scale


23/73

eoreferencing is the method by which a relationship can be established between

the map coordinates and the corresponding real world coordinates. 2his process

requires high level of accuracy. @ap was georefernced.

2he spherically undulating nature of the earth surface, when represented on two3

dimensional maps, result in some distortions unless a curved surface is used to

represent it. @ap proection is defined as a mathematical formula for representing the

curved surface of the earth on a flat surface of a mapB. It defines the relationship

between the map co3ordinates and the corresponding real world co3ordinates. 2he map

proection used in this work is *'R!'3-8.

3.5.2 I0t%g/ti0g /t/ /! O%l/(

2he ability to integrate data from two sources using map overlay is perhaps the

key I' analysis function. Gsing I' it is possible to take different thematic map layers

of the same area and overlay them one on top of the other to form a new layer. 2he

technique of I' map overlay may be linked to sieve mapping, to overlaying of tracing

of paper maps on a light table.

@ap overlay has many applications. As one layer it can be used for the visual

comparison of data layers. "verlays where new spatial data sets are created involve the

merging of data from two or more input data layers to create a new output data layer.

3.5.3 *!/ti/l I0t%!ol/tio0

'patial interpolation is the procedure of estimating the values of properties at un

sampled sites with an area covered by existing observations. A common application of

interpolation is for the construction of height contours.

/riging is an interpolation technique in which the surrounding measured values

are weighted to derive a prediction for an unmeasured location. !eights are based on the

distance between the measured points, the prediction locations, and the overall spatial

arrangement among the measured points. /riging is based on regionali&ed variable

theory, which assumes that the spatial variation in the data being modeled is statistically

homogeneous throughout the surface. 2hat is, the same pattern of variation can be

observed at all locations on the surface.

45


24/73

A I' offers many options for creating customi&ed maps and reports. A0* @A)

is used for the mapping needs, and I=H" to generate the final report. 2he map contains a

series of themes or coverages and descriptive information to interpret the information on

the map.

3.) CARL*ON WATER QUALITY INDEX

*arlson trophic state index was developed for use with lakes that have few rooted

aquatic plants and little non3algal turbidity. Gse of the index with lakes that do not have

these characteristics is not appropriate.

2he formulas for calculating the *arlson 2rophic 'tate Index values for 'ecchi

disk, chlorophylla, and total phosphorus are given below 2=?2) T 55


26/73

regression equations for all stations were made. Hrom these linear regression equations, a

predictor was defined for each nutrient based on two criteria< adusted 04(the highest+>

root mean square error (sqrt@'+ (the lowest+. 2hose criteria were used to choose the

predictive model. Hrom them, and because this resulting regression best illustrated the

distribution of the nutrients in the lake (U 04+, we were able to select a regression relation

that was constant in time and space.

CHAPTER 4

RE*ULT* AND DI*CU**ION*

4.1 GENERAL

As industriali&ation and urbani&ation progressed the aquatic ecosystem became

loaded with enormous quantities of nutrients, sediments and toxic materials. Hor the

47


27/73

assessment of the environmental quality and protection, monitoring of pollutants present

in the environment is highly essential. 2he unique feature of the Dake permits sea3lake

relation and interaction leading to large scale exchange of water and sediments.

4.2 WATER QUALITY ANALY*I*

2he present study was carried out for six months from Hebruary to Muly 4$$8. Lalues of

various physico3chemical parameters for the ten stations> =ear Amayi&hanchan thodu,

Jefore Joat *lub, After Joat club, *entre of Akkulam Dake, @anakkunnu,

"ruvathilkotta, =ear 2. '. *anal, =ear English Indian *lays, =ear 'IHH' and =ear 'ea

from Hebruary to Muly 4$$8 was plotted. Fata for the month of Hebruary 4$$8 are shown

in Appendix I

4.2.1 !H

!hen p1 is outside the range of 6.6 to 8.6, most aquatic organisms become

stressed and populations of some species can become depressed or disappear entirely.

4#


28/73

48


29/73

8ig 4.1. *%/&o0/l =/i/tio0 o7 !H

0aw sewage reaches the Akkulam lake through Amayi&hanchan thodu. At this point, p1

is having a minimum of 7.4 in Hebruary. 2he minimum value of p1 7.7 was recorded at

station after this point (beyond boat club+ in Hebruary. 2hen it was increased to 7.78 at

the centre of Akkulam lake. At the point where 2. '. canal meets the Leli lake, p1 is 7.#

and near sea, its value is 7.#-. 2his may be due to nearness to the sea. Increase in p1 was

observed in April, @ay and Mune due to rain. "ccasional breaching of the sand bar during

rainy season results in intrusion of sea water having p1 so that Leli side of the lake water

has higher p1 values during monsoon.

4.2.2 T'-iit(

2urbidity in water is caused by the presence of suspended matter, such as clay, silt

colloidal organic particles, )lankton and other microscopic organisms. 2urbidity is an

expression of certain light scattering and light3absorbing properties of water. 2urbidity is

an important parameter for characteri&ing the water quality.

4-


30/73

8ig 4.2 *%/&o0/l =/i/tio0 o7 T'-iit(

5$


31/73

0aw sewage enters the Akkulam lake through Amayi&hanchan thodu. @aximum turbidity

(55.8 =2G+ was observed in Hebruary at this point and this may be due to the turbid

particles in sewage. A maximum value of -.8 =2G (@arch+ was observed near the sea.

It is seen that turbidity increases during the monsoon periods at all stations.

4.2.3El%#ti#/l #o0'#tiit(

*onductivity is a measure of the ability of water to conduct an electric current,

which is dependent upon the concentration of charged particles (ions+ dissolved in the

water. @inimum value of $$micro'iemens was observed and a maximum value of

6$$micro 'iemens was observed during Muly.

5


32/73

8ig 4.3. *%/&o0/l =/i/tio0 o7 El%#ti#/l #o0'#tiit(

In Akkulam lake where sewage enters the water body, electrical conductivity is less as

less inorganic ions are present in sewage. It ranges from 58$ to5$$ micro siemens. It is

seen that the conductivity increases towards sea and the conductivity is maximum at 4$$

micro siemens near sea at Leli lake in Mune.

54


33/73

4.2.4 Di&&ol% o(g%0 /0 -iologi#/l o(g%0 %/0

"xygen in the dissolved form is essential to maintain biological life in water. .

Fissolved "xygen concentration is an important gauge of existing water quality and the

ability of a water body to support well balanced aerobic conditions.

55


34/73

8ig 4.4 *%/&o0/l /i/tio0& o7 DO /0 OD

2he main sources of dissolved oxygen in water are the atmosphere and aquatic

plants. In Akkulam lake where sewage enters through Amayi&hanchan thodu, lower value

of dissolved oxygen was observed. It is nil in @ay. In the centre of the Akkulam lake, its

value is &ero in @arch and April. Lery low values in F" content is observed in stations

located in the Akkulam side of the lake system. 2he organic pollution is the main reason

for the depletion of dissolved oxygen in the lake. 2he /annammoola 2hodu and *hakka

2hodu bring in organic rich land drainage and sewage. 2here is improvement in the

quality of water Leli lake towards the sea.

5


35/73

Jiological "xygen Femand indicates the amount of oxygen required for the

biological oxidation of organic matter. J"F has an inverse relationship with the F" and

direct relation with the phytoplankton. 2he minimum value of Jiological "xygen

Femand was recorded at the centre of the Aakkulam lake, $.7mg?l (@arch+ and

maximum value was recorded at the point were Amayi&hanchan thodu meets the

Aakkulam lake, 46.8mg?l (Hebruary+. Dower J"F values can be observed near the sea.

4.2.5 C"loi%

*hloride occurs naturally in all types of fresh water. *hloride is a mobile ion,B

meaning it is not removed by chemical or biological processes in soil or water. @any

products associated with human activities contain chloride (e.g., de3icing salts, water

softener salts, and bleach+. Although most fish are not affected until chloride

concentrations exceed #6$ ))@, increasing chloride concentrations are indicative of

other pollutants associated with human activity (such as automotive fluids from roads or

nutrients ? bacteria from septic systems+ reaching our waterways.

56


36/73

8ig 4.5. *%/&o0/l /i/tio0 o7 C"loi%

2he chloride concentration in the present study ranged having a maximum of 6$mg?D

in Muly and having a minimum of 4#mg?D in April. Its usually seen that higher values are

observed near the Leli side of the lake due to also of the intrusion of sea water along with

the drainage from land and sewage. In the present study chloride concentration is heavy

due to sewage disposal (JI'. --7, 46$mg?l+ and industrial pollution.

57


37/73

4.2.) Ao0i/#/l Nitog%0B Nitit% /0 Nit/t%

=utrients play an important role in an aquatic environment, which mainly governs

the phytoplankton growth and diversity. =itrates are the end products of decomposition

of organic matter and indicate that organic matter is fully oxidi&ed.

5#


38/73

8ig 4.)*%/&o0/l /i/tio0& o7 Ao0i/ #/l Nitog%0B 0itit% /0 0it/t%

In present study maximum concentration of ammoniacal nitrogen is found at

station where Amayi&hanchan thodu meets Akkulam Dake and it is also maximum at the

station where 2. '. canal meets Leli lake. It is seen that the input of sewage into the lake

has a profound effect in summer. =itrites are the products obtained by the oxidation of

ammonia. =itrates are the fully oxidi&ed form of ammoniacal compounds.

4.2., P"o&!"/t%

)hosphate is a vital nutrient for the growth of phytoplankton. @aximum

concentration of .$mg?D was observed in Hebruary which may be due to eutrophication

and a minimum of $.$54mg?D in Muly near the )o&hi. )hosphate concentration above

4mg?l is considered as an indication of high pollution.

58


39/73

5-


40/73

8ig 4.,. *%/&o0/l =/i/tio0 o7 P"o&!"/t%

2he excessive weed growth in the Akkulam Leli Dake has resulted in

impairment of many of the lake related activities. In addition, phosphorous is contributed

to the water body by domestic sewage, industrial effluent and drainage from agricultural

lands where excess phosphatic fertili&ers are used.

4.2.9 Tot/l H/0%&&

1ard water forms precipitates on boiling or when soap is added to it. 1ardness is

due to the presence of calcium, magnesium or ferrous (iron salts+ as chloride, sulphate or

bicarbonates. 2he degree of hardness is equivalent to *a*"5 concentration and

designated as soft ($37$ mg?+, medium hard (7$34$ mg?+, hard (4$38$ mg?+, very

hard (U8$ mg?+.

$


41/73

8ig 4.9 *%/&o0/l =/i/tio0 o7 Tot/l H/0%&&


42/73

1igher values of total hardness are found near the )o&hi. Its value varies from 58 to

4-7 mg?l in this area. 2his may be due to nearness to the sea. 2he values of total

hardness are 67 mg?l at "ruvathilkotta and 4-7 mg?l near sea.

4.3 *EDI$ENT ANALY*I*

Dakes display a wide variety of geological and physiographic characteristics. 'amples

were collected from four stations for analysis during Fecember 4$$#, April 4$$8 and Muly

4$$8. 1ydrogen ion concentration of soil depends largely on relative amounts of the

absorbed hydrogen and metallic ions. 1ydrogen ion concentration of sediments samples

get drastically changed due to disposal of industrial waste sewage etc. 2he four stations

selected are the following given below

!here 'tation Amayi&hanchan thodu

'tation 4 AkkulamR*entre

'tation 5 LeliR2' canal

'tation LeliRnear sea shore

4.3.1 !H /0 El%#ti#/l Co0'#tiit(

p1 of sediments ranged from 5.683#.4- and conductivity from 6$$ -$m'?cm.

At 'tation 5 there may be a contamination from the English India clay Dtd causing a

lowering of p1 of 5.68 at April 4$$8. A high conductivity of -$m'?cm is observed at

station 4 due to eutrophication during Fecember 4$$#.

T/-l% 4.1 !H o7 &%i%0t &/!l%&

Lo#/tio0 D%#%-% 2;;, A!il 2;;9

*t/tio0 1 6.56 6.$

*t/tio0 2 6.5# 6.4*t/tio0 3 6.78 5.68

*t/tio0 4 #.4- 6.#8

T/-l% 4.2 Co0'#tiit( *#6 o7 &%i%0t &/!l%&

4


43/73

Lo#/tio0 D%#%-% 2;;, A!il 2;;9

*t/tio0 1 $58 $6

*t/tio0 2 -$ 466$

*t/tio0 3 478$ 55$

*t/tio0 4 6$$ 7$

4.3.2 T%t'%

2exture of the sediment samples showed that the silt content was greater near the

Amayi&hanchan thodu ie. the upper reaches of the lake and sand and clay was greater

near the sea station.

T/-l% 4.3 T%t'% o7 &%i%0t &/!l%&

Lo#/tio0 D%#%-% 2;;, A!il 2;;9

*/0 *ilt Cl/( */0 *ilt Cl/(*t/tio0

1

#.# -4. $.7

*t/tio0

2

-.8 88.8 . $.76 6$.8 -.6-

*t/tio0

3

6. 65.6# .$5 .58 46.-6 74.7#

*t/tio0

4

#. 4#. .6 6$ 6.5 .6#

4.3.3 Og/0i# C/-o0

'uspended organic matter received by the lake through land run off, sewage etc

settle and forms part of bottom sediments. Fead aquatic plants and organisms also

contribute much to the organic content of the sediments. Enriched with organic matter,

the sediments acts as good reservoir of nutrients.

T/-l% 4.4 P%#%0t/g% og/0i# #/-o0 o7 &%i%0t &/!l%&

Lo#/tio0 D%#%-% 2;;, A!il 2;;9

*t/tio0 1 4.$54% .-#8

5


44/73

*t/tio0 2 #.6% #.4%

*t/tio0 3 #.6% 7.6%

*t/tio0 4 $ $.447%

@aximum value of #.6% was recorded at station 4 during Fecember 4$$# and

minimum value of $ was observed at station during Fecember 4$$#. 2he sediments at

Akkulam part comprise of silty clay while that in the Leli part is sandy. *ontribution by

/annammoola 2hodu and debris of aquatic weeds are also more at Akkulam part of the

lake.

4.4 WATER QUALITY INDEX

!ater quality index serves as a tool to examine trends, to highlight specific water

quality conditions. =ational 'anitation Houndation !ater ;uality Index is used for the

study. It has been calculated on the basis of water quality parameters namely dissolved

oxygen, fecal coliform, p1 and J"F. 2he variation can be described on the basis of the

following descriptor words suggested for reporting the ='H !;I. 2hese codes could be

effectively used to classify the water quality while preparing the water quality maps. 2his

information could be then readily used to take suitable control actions for water quality

restoration or improvement.

T/-l% 4.5 N*8 WQI 7o t"% *'% /0 $o0&oo0 P%io

*t/tio0& *'% $o0&oo0

Amayi&hanchan 2hodu 5.4 57.7

After Joat *lub 5#.$8 57.-$

@anakkunnu 4-.6# 5-.#4

2' *anal 55.8# 5-.-4

'IHH' .# $.45

Lariation of water quality index along the Dake is seen above in 2able .6. !ater

;uality of the lake is described to be badB according to ='H !;I. !ater quality index

is 4-.6# at @anakkunnu indicating water quality is bad at this point mainly due to low

mixing. !ater quality indices at 2' *anal and 'IHH' are ranging from 55.8# to .#

respectively indicating quality of water is bad at these points due to the land drainages.


45/73

4.5 CREATION O8 THE$ATIC $AP* U*ING GI*

2he result of geographic analysis can be communicated by maps (a graphical

representation of data+, reports ( a written description of the results+ or both. 2he final

product should relate directly to the obectives of the proect. 2he 2hiruvananthapuram

corporation is digiti&ed. 2he details of the maor existing roads have been delineated from


46/73

8. =ear English Indian *lays

-. =ear 'IHH'

$. =ear 'ea

7


47/73

8ig 4.: T"%/ti# /! &"o?i0g &/!l% !oi0t&

#


48/73

8ig 4.1; T"%/ti# /! &"o?i0g o/ /0 /il?/( 0%t?o

8


49/73

8ig 4.11 T"%/ti# /! &"o?i0g L/%B &t%/ /0 ti-'t/i%&

-


50/73

8ig 4.12 T"%/ti# /! &"o?i0g OD /i/tio0

Hig .4 shows J"F is higher towards the Leli lake causing a profound effect on

the 'IHH' station.

6$


51/73

8ig 4.13. T"%/ti# /! &"o?i0g DO /i/tio0

Hig .5 shows F" is very low in Akkulam lake due to the drains from the

Amayi&hanchan 2hodu and )arvathy )uthenar. !hereas F" increases as it moves

towards the sea due to the intrusion from the sea

6


52/73

8ig 4.14 T"%/ti# /! &"o?i0g COD /i/tio0

Hig . shows *"F is very much higher towards the Leli lake and at some

stations of the Akkulam lake because *"F is mainly contributed due to the drains from

the land drainage and industrial effluents

64


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8ig 4.15 T"%/ti# /! &"o?i0g !H /i/tio0

Hig .6 show p1 is higher at English India *lay Dtd station due to the

contamination from the industry. !hereas the station where Amayi&hanchan 2hodu

meets the Akkulam lake has lower p1 due to acidic sewage draining from the 2hodu.

65


54/73

8ig4.1) T"%/ti# /! &"o?i0g *o'#%& o7 #o0t/i0/tio0

Hig .7 shows the contamination sources in the 2hiruvananthapuram corporation

contributing towards the Akkulam Leli lake causing the deterioration of the lake.

*ontamination mainly occurs due to the overflows from the pumping stations, sewage

farm, boat club, English India clay ltd and land drainages.

6


55/73

8ig 4.1, O%7lo? 7o P/ttoo P'!i0g *t/tio0

8ig 4.19 O%7lo? 7o Pl/oo P'!i0g *t/tio0

66


56/73

8ig 4.1: O%7lo? 7o $'i0@/!/l/ P'!i0g *t/tio0

8ig 4.2; O%7lo? 7o K/00/ool/ P'!i0g *t/tio0

67


57/73

8ig4.21 T"%/ti# /! &"o?i0g Co0to' l/(o't

Hig .4 shows the digital elevation model of the 2hiruvananthapuram *orporation.

@ost of the land drains flows directly into the lake due to gravity flow.

6#


58/73

4.) A**E**$ENT O8 EUTROPHIC CONDITION O8 THE LAKE

2he 2rophic 'tatus Index can serve as a standard of trophic measurement against

which comparisons can be made between the many chemical and biological components

of the lake system that are related to trophic status. 2he result could be a more complete

and dynamic picture of how these components relate to one another and to the lake

ecosystem as a whole.

2'I values for the month of @ay are plotted in fig .44. 2he 2otal )hosphorous

and 'ecchi Fisk 2'I values remained higher than the *hlorophyll 2'I values.

*hlorophyll or total phosphorus is not considered as the basis of a definition of trophic

state but only as indicators of a more broadly defined concept. 2he best indicator of

trophic status may vary from lake to lake and also seasonally. 2he lake was receiving

most of its phosphorous from sewage effluent and their was noticeable deterioration of

water quality near the boat club and centre of Akkulam Dake. 1eavy algal blooms are

possible throughout the summer with dense macrophyte beds, but extent limited by light

penetration. "ften its classified as hypereutrophic.

8ig 4.22 To!i# &t/t'& i0% o7 t"% l/%Hig .44 shows that the 2'I values of chlorophyll lies in the range of 5$36$ i.e in

the mesotrophic state. 2'I values of total phosphorous and 'ecchi distance lies in the

range of #$3-$i.e in the hypereutrohic state. According to the relation non algal

particulates or colour dominate light attenuation.

68


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8ig 4.23 T*I o7 P"o&!"oo'&

Hig .45 shows that the high 2'I value of phosphorous is seen in the Akkulam lake due to

high eutrophication.

6-


60/73

!hen chlorophyll values are converted to 2'I, however, they can be seen to be

responding rapidly to enrichment, and the changes parallel those in the 2'I values based

7$

8ig 4.24 T*I o7 *%##"i Di&


61/73

on transparency. Dakes will become anoxic in the hypolimnion during the summer.

7


62/73

Hig .4 shows that high 2'I value of 'ecchi distance is observed at station after boat

club due to eutrophication.

74


63/73

8ig 4.25 T*I o7 C"loo!"(ll

2he index can be used for regional classification of all surface waters, including

streams and rivers. Any body of water could be classified using the total phosphorus

index, which is essentially a predictor of potential algal biomass

75


64/73

4., *TATI*TICAL ANALY*I*

2he simple linear regression was determined for the ten stations from Hebruary to

Muly 4$$8, using the variables ammoniacal nitrogen, nitrite, nitrate and phosphate. Hrom

the correlation matrix given in 2able .7, it is seen that a strong linear relationship exists

at certain stations.

*t/tio0Ao0i/#/l

0itog%0Nitit%FN Nit/t%FN P"o&!"/t%

Akkulam Dake

1. Amayi&hanchan

2hodu

(6.4543$.48x+

$.#84

$.$#8 $.44 (.-483.5-8x+

$.847

2. Jeyond boat

club

(6.443$.5$#x+

$.#84

$.57 $.5$# (6.83$.-6x+

$.7#

3.After Joat club $.-# (.845347.-x+

$.#

$.68 (6.-3$x+

$.747

4. *entre of

Akkulam Dake

(.-3$.55#x+

$.745

(.738.4-x+

$.7##

$.45 $.7#

5. @anakkunnu $.57# (6.$73$.#x+

$.7-

(5.-63$.4x+

$.77

$.#5

). "ruvathilkotta (.--3$.5#x+

$.7-4

$.$# $ $.7

7


65/73

Leli Dake

,. 2' *anal $.5 $.585 $.76 $

9. English India

*lay Dtd

(6.$3$.64x+

$.7#6

(.7-3.74x+

$.#84

$.4-# (6.7834.6x+

$.777

:. 'IHH' $. (6.#53#.58x+

$.875

$.476 (6.7-63.66x+

$.7-

1;.Leli near sea $.554 (6.4#34.84x+

$.#6-

$.8# (.84537.5x+

$.8$-

T/-l% 4.) Co%l/tio0 &ig0i7i#/0#% o7 /o0i/#/l 0itog%0B 0itit%B 0it/t% /0

!"o&!"/t% ?it" &t/tio0&

'ampling stations indicate that the ammoniacal nitrogen samples drawn near the

Amayi&hanchan 2hodu ('tation + have higher scores compared to other 'tations. 2his is

clearly due to the fact that 'tation is influenced by the inflow of sewage from the

Amayi&hanchan 2hodu which also brings in the nutrients, especially phosphate. !hereas

nitrate rises toward the @anakkunnu as complete oxidation of ammonium takes place and

is the final oxidation stage. At station ,4 and 7 the sewage is input into the lake through

the Amayi&hanchan 2hodu and )arvathy )uthenar causes an increase in ammoniacal

nitrogen which gives a high relationship with those stations. !hereas the nitrite and

nitrate has lower values as decomposition of the organic matter is yet to be started at

those stations. 'ewage is relatively rich in phosphorous compounds also which causes a

high relation at station and $ due to the sewage input from Amayi&hanchan 2hodu and

due to the intrusion from sea.

2he stations included in this predictive model for ammoniacal nitrogen are

Study and Assessment of an Eutrophied Inland Water body

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