INTRODUCTION TO WATER SUPPLY AND WASTEWATER MANAGEMENT IN ... · PDF fileintroduction to water...

INTRODUCTION TO WATER SUPPLY AND WASTEWATER MANAGEMENT

IN HUE CITY, VIETNAM

Pham Khac LIEU*, Nguyen Bac GIANG Department of Environmental Science

College of Sciences, Hue University, Vietnam

GEOSS-AP/AWCI Session, Tokyo, May 27th 2014

Contents

1. Hue city at a glance 2. Water sources in Hue 3. Water use and supply in Hue 4. Wastewater management in Hue 5. Threats to water supply and WW

management in Hue 6. Remarks

GEOSS-AP/AWCI Session, Tokyo, May 27th 2014 2

1. Hue City at a glance

Hue City

Phu Vang

District

Huong Thuy Town

Huong Tra

Town

Huong Tra Town

Hue city

Administrative division in Vietnam Province/City* (都道府県)

City/District/Town (市) Ward/Commune

Thua Thien Hue Province


http://en.wiktionary.org/wiki/%E9%83%BD%E9%81%93%E5%BA%9C%E7%9C%8C

1. Hue City at a glance Hue City • Area: 71.7 km2

• Population: 342,500 (2011) • Ancient capital of Vietnam

(18th ~ first-half 20th centuries)

• A World Cultural Heritage (since 1993 by UNESCO)

• Famous destination for tourists, a “festival city” of Vietnam

The Citadel

The King’s Tomb Source: Hue city’s Statistics Office, 2011


1. Hue City at a glance

Land use (2010)

Economic activities (2009)

Agriculture22.5%

Forestry5.4%

Specially used

41.2%

Residential29.1%

Unused1.8%

Industry & construction

28.5%

Services & tourism70.2%

Agro-forestry1.3%

(Source: Hue city’s Statistical Yearbook, 2010, 2011)


1. Hue City at a glance Climate conditions • Tropical monsoon, two seasons (dry: Mar ~ Aug, rainy:

Sep ~ Feb) • Annual average temp.: 24-25°C (highest: 38-40°C) • Annual rainfall: 2,500 mm


Source: www.huecity.gov.vn

6

1. Hue City at a glance Flood in Hue city • Early flood: May- Jun., main flood: Oct.- Dec. • No. of floods per year: 3-5 (average), 9 (highest) • Flood amplitude: 3-5 m • Flooding duration: 3 – 5 days


Hue Citadel’s Gate before and during flooding

7

• Surface water is major source

• Plentiful water thanks to high rainfall and extensive network of rivers (Huong river and its branches)

• Unequally distributed rainfall over the seasons causes flooding in the wet, and some droughts in the dry season.

A dense river network around Hue City

2. Water sources in Hue


Huong river (Perfume river)

Variation in monthly average flow rate of Huong river’s tributaries (Tinh, 2010)

•Average flow: 9,660 m3/min •Lowest flow: 1,632 m3/min



• catchment area: 2,830 km2

• 3 tributaries (2 in upper and 1 in lower section)

• 4 branches within city’s boundary

• irregular flow: 70 -75 % of total flow from Oct.- Dec.

• upstream dams and downstream barrage

9

Sample pH DO, mg/L

COD, mg/L

BOD5, mg/L

SS, mg/L

NO3-N, mg/L

NH4-N, mg/L

PO4-P, mg/L

RW1 6.6 7.7 9.7 2.5 14.1 0.3 0.1 0.1

RW2 7.2 7.0 20.5 1.3 23.0 1.0 0.3 0.1

RW3 7.1 6.6 18.0 2.5 18.1 0.8 0.1 0.1

RW4 6.9 5.7 10.5 3.8 12.7 1.8 4.2 0.0

RW5 7.2 5.7 7.6 3.2 10.2 1.2 2.1 0.0

Average 7.0 6.5 13.3 2.6 15.6 1.0 1.3 0.1

National regulation*

A1 6-8.5 6.0 10 4 20 2 0.1 0.1

A2 6-8.5 5.0 15 6 30 5 0.2 0.2

Water quality of Huong River • Generally good for domestic use • Slightly organic, nutrient and pathogenic pollution

*National Technical Regulation for Surface Water Quality (QCVN 08:2008/BTNMT): A1-applied for surface water able to use for domestic supply without treatment. A2-applied for surface water able to use for domestic supply with appropriate treatment

Water quality of Huong river and branches in 2011 (survey data)



Water quality of Huong River at Van Nien Intake and Da Vien Intake in 2011 (Source: Monitoring data by HueWACO)

0

5

10

15

20

25

30

35

Jan. Feb. Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Turb

idity

(NTU

)

Van Nien Intake Da Vien Intake

0.00

0.05

0.10

0.15

0.20


NH

4-N

(mg-

N/L

)


Nationalstandard value

0

1000

2000

3000

4000

5000


Tota

l col

iform

s (M

PN/1

00m

L)


National standard value



3.1. Water use • Public piped water is main use in Hue city

97%

1% 2%

Public piped water Drilled wells Dug wells

Distribution of domestic water use by households in Hue city (Center

for Preventive Medicine, 2010)

• Tap water coverage: o 100% area-based

since 2010 (HueWACO) o 97% households

(Center for Preventive Medicine, 2010)

o 99% population-based (HueWACO, 2013)

3. Water use and supply in Hue

HueWACO: Thua Thien Hue Water Supply & Construction State-owned Co.Ltd.


Public piped water use • 76% for residential use • per capita daily

consumption: o 105 L/day (2008), o 115 L/day (2009), o 127 L/day (2010, 2011)

(HUEWACO, 2012).

o 123 L/day in 2011 (survey on 300 households)

Public piped water use by sectors in 2011 (HueWACO)

76%

11%6%

7%

Residential Institutional Industrial Commercial



3.2. Water supply • HueWACO: only one water supply company • 23 purification plants with total capacity of

185,000 m3/d for the whole province (2102) • 3 purification plants located in Hue city with

114,500 m3/d • Total length of network > 1600 km • Water source: 100% surface water • Water leakage <12%.



Tap water quality • Meets all requirements by

National Technical Regulation on Drinking Water Quality (QCVN 01:2009/BYT)

• Particularly, turbidity always 10 times lower than limitation value (0.2 NTU vs. 2.0 NTU)

• Declared Water Safety Plan in 2008 (one of three companies in South-East Asia recognized by WHO)



4.1. Wastewater generation • Domestic WW major, industrial WW minor

– Domestic WW: 36,600 m3/d – Industrial WW: 2,000 m3/d

(our estimation based on water balance, 2010) • Domestic wastewater generation

– 108 L/cap/d (our estimation, above mentioned)

– Standard design value for for I-class city: 120 L/cap/d (Vietnam Building Code QCVN 01:2008/BXD)

4. Wastewater management in Hue



Huong River

48,466 m3

Public water supply system

44,104 m3

In-plant use

9% = 4,362 m3

Households

40,364 m3

38,812 m3

Water leakage

12% = 5,259 m3

Well water

4% population

Grey water 36,328 m3

Seepage

3,229 m3

Septic tank

Sewer

10,989 m3

Open channel

10,989m3

Culvert

14,652 m3

301.4 m3

31,496 m3 36,629 m3

Excreta (urine) 347.6 m3

8%

90% 4, 832m3

Water bodies

Water balance for Hue city (daily based) (2010)


4.2. Domestic wastewater characteristics Parameter 1997 2005 2006-

2007 2010-2011

2015 design values

National regulation

COD, mg/L 170 223 298 181 300 N.A BOD5, mg/L 115 151 213 86 200 30 SS, mg/L 77 113 155 37 250 50 T-N, mg/L 25 15 20.9 29 40 30 (NO3-N)

T-P, mg/L 11 9 1.7 3 5 6

Data source Hop et al., 1997

HEPCO, 2007

HEPCO, 2007

Our survey, 2011

HEPCO, 2007

QCVN 14:2008/ BTNMT

Domestic WW in Hue is not so strongly polluted in terms of organic and nutrient contents.



4.3.Sewerage and drainage network

HEPCO: Hue Urban Environment and Public Works State-owned Co.Ltd.



– Combined system – Components:

• 81 km of ditches, 127 km of sewers, 9035 manholes

• 16 km canals and rivers, • 40 ponds

– Service coverage: ~ 30% – Gravity-principal

operation (HEPCO, 2013)

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In Hue Citadel: ponds and canal play important role as drainage function

Ponds Sewers& Manholes

Huong River



Inundation due to poor drainage system • Several times a year • Estimation: rain at probability of 50%, 72 mm in 3 h

70% of streets under 0.1 – 0.5 m (Provincial Dept. of Transportation)

Inundated after heavy rain (Oct., 2007) Inundated after heavy rain (Oct., 2009)



4.4. Domestic wastewater treatment • At present

– No central WW treatment plant in Hue – pretreated with septic tank or simple settling tank or

directly discharged into rivers, ponds,… • On going project “Water Environment

Improvement in Hue city” (24 bill.JPY, 87% loaned from Japan) – 1st phase (2008-2016)

• targets to south side of Huong River (new urban areas) • construction of a MWWTP with capacity of 30,000 m3/d

– 2nd phase (after 2016): • upgrade treatment plant in south side 40,000 m3/d • collection and treatment system in the north side (HEPCO, 2007; Thua Thien Hue PPC, 2009).



Planned location of WWTPs in Hue



4.5. Household sanitation (as of 2011) • Accessibility to toilet: 97.8% • Hygienic toilet: 95%

Treatment facilities 2006 2009 2011 Septic tank 80.4 86.7 87.1 Cesspool (seepage pit) 5.3 4.5 3.6 Double vault latrine 2.5 2.6 3.8 Ventilated pit latrine 0.7 0.8 1.2 Others 4.1 0.6 2.1 Sum (having access to toilet) 92.9 95.2 97.8

Data source: Provincial Center for Preventive Medicine, 2011



On-site treatment facilities (% of total households)

24

5. Threats to water supply and wastewater management in Hue

Factors Possible impacts Expansion of the city

Lower service coverage

Climate change More inundation Saline intrusion

Operation of upstream works

Reducing peak flood Worse quality of water source


Example: Inundation under climate change (MONRE, 2012) • Sea level rise of 1 m: about 0.4% of area of Hue city inundated • However, annual rainfall will increase 3 – 5% (2050) and 4 – 8%

(2100), max.daily rainfall will increase 20% (scenario B2)



Inundation map of Hue city at maximum water depth for the year 2100 under B2 scenario Source: Tran Thuc, VNU Journal of Science, 26(2010)

Hue

26

Example: Upstream dams and reservoirs - possible impacts: – Changes in flooding regime/duration – prevents from peak floods – Changes in water quality, e.g. higher Mn (II), DOC concentrations

Ta Trach Reservoir (under construction) • Dam height = 56 m • Dam length = 1,112m • Storage capacity = 646 Mm3

Binh Dien Dam (operated) • Dam height = 83.6 m • Dam length = 362.8m • Storage capacity = 424 Mm3

Huong Dien Reservoir (operated) • Dam height = 82.5 m • Dam length = 180 m • Storage capacity = 820 Mm3 HUE



6. Remarks • Current status of water supply and WW

management in Hue city: – Good water supply practice: plentiful source,

reliable supply system, high quality. – Inadequate drainage and sewerage system:

low coverage, no sewage treatment, etc.⇒ health risk during inundation and flooding.

– Upstream works and climate change may bring about negative impacts on water environment

• An inter-linkage study on water-related health risk linked to flood and inundation is very important.


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