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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
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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
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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
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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)
GEOSS-AP/AWCI Session, Tokyo, May 27th 2014
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
GEOSS-AP/AWCI Session, Tokyo, May 27th 2014
Source: www.huecity.gov.vn
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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
GEOSS-AP/AWCI Session, Tokyo, May 27th 2014
Hue Citadel’s Gate before and during flooding
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• 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
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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
2. Water sources in Hue
GEOSS-AP/AWCI Session, Tokyo, May 27th 2014
• 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)
2. Water sources in Hue
GEOSS-AP/AWCI Session, Tokyo, May 27th 2014
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
Jan. Feb. Mar Apr May Jun Jul Aug Sep Oct Nov Dec
NH
4-N
(mg-
N/L
)
Van Nien Intake Da Vien Intake
Nationalstandard value
0
1000
2000
3000
4000
5000
Jan. Feb. Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Tota
l col
iform
s (M
PN/1
00m
L)
Van Nien Intake Da Vien Intake
National standard value
2. Water sources in Hue
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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.
GEOSS-AP/AWCI Session, Tokyo, May 27th 2014
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. Water use and supply in Hue
GEOSS-AP/AWCI Session, Tokyo, May 27th 2014
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%.
3. Water use and supply in Hue
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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)
3. Water use and supply in Hue
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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
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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)
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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. Wastewater management in Hue
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4.3.Sewerage and drainage network
HEPCO: Hue Urban Environment and Public Works State-owned Co.Ltd.
4. Wastewater management in Hue
GEOSS-AP/AWCI Session, Tokyo, May 27th 2014
– 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
4. Wastewater management in Hue
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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. Wastewater management in Hue
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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).
4. Wastewater management in Hue
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Planned location of WWTPs in Hue
4. Wastewater management in Hue
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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
4. Wastewater management in Hue
GEOSS-AP/AWCI Session, Tokyo, May 27th 2014
On-site treatment facilities (% of total households)
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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
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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)
5. Threats to water supply and wastewater management in Hue
GEOSS-AP/AWCI Session, Tokyo, May 27th 2014
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
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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
5. Threats to water supply and wastewater management in Hue
GEOSS-AP/AWCI Session, Tokyo, May 27th 2014
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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GEOSS-AP/AWCI Session, Tokyo, May 27th 2014