Download - Overview of Water Supply in Asian Cities
Overview of Water Supply in
Asian Cities
Exploring Water City Planning for Bangkok
Final Workshop: Extending Urban Metabolism
Novotel Siam Square, Bangkok Thailand
13 November 2014
Dr. Vitor Vieira Vasconcelos
CNPq scholarship (Brazil)
Stockholm Environment Institute
Developed with the support of CNPq – National Council for
Technological and Scientific Development – Brazil.
Contents
• Challenges faced by Asian cities
• Constraints on choices for water supply
• Comparison of water sources and losses for 10
cities in Asia
• General trends of water supply
– How Bangkok fits into these patterns
• Open questions on strategies for water
management
Challenges of Asian Megacities
• Urban Growth
– Increasing demand
– Pollution of existing resources
• Private or non-formal water extraction
• Limited budget or revenue capacity
Water Quantity Constraints
• Surface water
– Rivers and Reservoirs capacity
– Is there a water supply
structure available?
• Groundwater
– Aquifer depletion
– Subsidence
Which option
to use?
Water Quality Constraints
• Surface water
– Sewage
• Groundwater
– Aquifer geochemistry
– Saltwater intrusion
– Leakage from surface water
• Rivers and canals
• Flood
Which option
to use?
A Comparison on Water Sources
• Each city has a different natural potential
• Each city has as a different societal history
• What is similar? What is different?
• Can we learn with the history of each other?
Water Sources
0% 20% 40% 60% 80% 100%
Singapore
Bangalore
Manila
Dhaka
Kandy
Colombo
Tianjin
Ho Chi Minh
Bandung
Bangkok
Surface Water Groundwater
Rain Harvest Reclamation Water
Desalinization
IGES - Institute for
Global Environmental
(2007). Sustainable
Groundwater
Management in Asian
Cities. Japan. 179p.
Haq, KA (2006) Water Management in Dhaka.
Water Resources Development 22(2): 291–311.
Singapore National Water Agency. (2013). Our
Water, Our Future. http://www.pub.gov.sg/
Grönwall, JT, et al. (2010) Groundwater, self-
supply and poor urban dwellers: A review with
case studies of Bangalore and Lusaka (26). IIED
Taniguchi, M 2011,03 “Groundwater and
Subsurface Environments – Human Impacts in
Asian Coastal Cities – “. Springer, 312pp
0% 20% 40% 60% 80% 100%
Singapore
Bangalore
Manila
Dhaka
Kandy
Colombo
Tianjin
Ho Chi Minh
Bandung
Bangkok
Surface Water GroundwaterRain Harvest Reclamation WaterDesalinization
Water Sources
Large
infrastructure
for surface
water supply
0% 20% 40% 60% 80% 100%
Singapore
Bangalore
Manila
Dhaka
Kandy
Colombo
Tianjin
Ho Chi Minh
Bandung
Bangkok
Surface Water GroundwaterRain Harvest Reclamation WaterDesalinization
Water Sources
Large deltas,
but unequal
infrastructure for
surface water
supply
Water Sources
0% 20% 40% 60% 80% 100%
Singapore
Bangalore
Manila
Dhaka
Kandy
Colombo
Tianjin
Ho Chi Minh
Bandung
Bangkok
Surface Water GroundwaterRain Harvest Reclamation WaterDesalinization
Plateaus -
limited surface
and groundwater
sources
Water Sources
0% 20% 40% 60% 80% 100%
Singapore
Bangalore
Manila
Dhaka
Kandy
Colombo
Tianjin
Ho Chi Minh
Bandung
Bangkok
Surface Water GroundwaterRain Harvest Reclamation WaterDesalinization
Small basins,
relying on
inter-basin
transfer
Water Sources
Coastal cities:
risk of
saltwater
intrusion
0% 20% 40% 60% 80% 100%
Singapore
Bangalore
Manila
Dhaka
Kandy
Colombo
Tianjin
Ho Chi Minh
Bandung
Bangkok
Surface Water GroundwaterRain Harvest Reclamation WaterDesalinization
0% 20% 40% 60% 80% 100%
Singapore
Bangalore
Manila
Dhaka
Kandy
Colombo
Tianjin
Ho Chi Minh
Bandung
Bangkok
Surface Water GroundwaterRain Harvest Reclamation WaterDesalinization
Water Sources
Coastal cities:
risk of salt
intrusion
Deltas
0% 20% 40% 60% 80% 100%
Singapore
Bangalore
Manila
Dhaka
Kandy
Colombo
Tianjin
Ho Chi Minh
Bandung
Bangkok
Surface Water GroundwaterRain Harvest Reclamation WaterDesalinization
Water Losses
• Pressure X Losses
• Pipes age
• Subsidence
• Reforms:
– Management focus
– Capital
Efficiency changing along time
Wa
ter
Loss
es
(%)
0
10
20
30
40
50
60
70
19
93
19
95
19
97
19
99
20
01
20
03
20
05
20
07
20
09
20
11
20
13
Manila (east)
Dhaka
Colombo
Bandung
Bangalore
Bangkok
Ho Chi Minh
Kandy
Singapore
Source: WMA and many reference databases
What could we learn?• The private or public choice for surface or groundwater
depends on constraints of quantity and quality
• Developing surface water supply is an essential policy to deal with groundwater over-abstraction
• Coastal, deltaic and plateau cities face different challenges on constraints to surface and groundwater use
• Dealing with water loss is a challenging but rewarding measure
Typical evolution of water supply sources in large cities (surrounded by high-yielding aquifers)
Foster, S., Vairavamoorthy, K. (2013). GWP- Urban Groundwater: Policies and Institutions for Integrated Management. GWP Perspectives Papers. 20p.
Water table trend in Bangkok
Source : Department of Groundwater Resources
Water table trend in Bangkok
Endo, T. Sinking Cities and Governmental Action:
Institutional Responses to Land Subsidence in
Osaka and Bangkok. In: Taniguchi, M 2011,03
“Groundwater and Subsurface Environments –
Human Impacts in Asian Coastal Cities – “.
Springer, 312pp
Mil
lio
n m
3/d
ay
1st critical zoning
(1983)
2st critical zoning
(1994)
3st critical zoning
(2000)
4.94
(2013)
1st Revision of GW Act
(1992)
2nd Revision of GW Act
(2003)
Water table trend in Samutprakarn
History of Groundwater Use
Yoshikoshi, A. Urban Development and Water Environment Changes in Asian Megacities. In: Taniguchi, M (2011) Groundwater
and Subsurface Environments: Human Impacts in Asian Coastal Cities. Springer, 312pp
Dhaka
Ho Chi Min
Household Demand
Taniguchi, M (2011) Groundwater and Subsurface Environments: Human Impacts in Asian Coastal Cities. Springer, 312pp
Pattern for
cities in
developing
countries?
50
70
90
110
130
150
170
190
Residential Water Use Per Capita in Bangkok
Water Use Per Capita
m3/y
ea
r
Source: WMA
Concluding Reflections• Policy enforcement and tariff scheme in Bangkok
were effective in returning the overall level of
water table over 15 years.
– A new zoning could evidence
• Remaining critical areas where there is still subsidence, in
Bangkok and expanded neighborhood
• If we should prepare for the risk of uplifting
• Household demand tends to stabilize
– And what is next? Could we decrease household
demand?
Knowing where we are,
and estimating the possible trends,
where should we prioritize the investments?
- Network rehabilitation?
- Enforcement on control of groundwater use?
- Development of surface water supply?
- Wastewater treatment?
Concluding Reflections