integrated urban water resources management in sri lanka...
TRANSCRIPT
Integrated Urban Water Resources
Management in Sri Lanka
Background, Issues and Training
Needs
N.T.S. WIJESEKERA
Department of Civil Engineering
University of Moratuwa,
Moratuwa, Sri Lanka
The Democratic Socialist
Republic of Sri Lanka
An Island in the Indian Ocean
surrounded by tropical
beaches
Latitude 5'55" - 9'51" &
Longitude 79'42" - 81'52".
Total land area is 65,610 sq. km
870 sq km of inland water
(1.3% of total)
Length-445 km Breadth- 225 km
SRI LANKA
Population of Sri Lanka is about 20 million
Density is highest in the southwest : Colombo
74% of the population are concentrated in
the southwest
The net population growth is about 1.2%.
21.5% Live in Designated Urban Areas
In Colombo and
Suburbs
Impervious Area is
varying around 25
– 40% in
residential areas
In commercial area
this is
approximately 95%
Jaffna
Anuradhapura
Trincomalee
Negombo Kurunegala
Matara
Close to Water
Bodies
Lake
Ocean
Colombo
Galle
Kandy
River Delta,
Habour,
Low Lying,
Land
Filling,
Water
Intakes,
Drainage
75% Urban and 14% Rural are served with
Pipe Borne Water
Demand for safe water increases by 8-10%
each year
Most urban water supply schemes do not
have the capability for 24 hr service
The Water Supply Sector Expenditure
0%
10%
20%
30%
40%
50%
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
Getting Reduced
Water Sector Issues in the Urban Areas
of Sri Lanka
• Urban Water Supply and Sanitation
• Urban Area Flooding
• Quality of Water Bodies
Urban Water Supply
Sources: Mostly,- Surface Water Several, - Groundwater
Colombo – Surface water from Kelani and Kalu Rivers
Kandy – Mahaweli River
Galle – Gin River
Water is pumped from Rivers to storage reservoirs and replenished
Water availability is the availability of river flow: In the Dry Season Salt
water intrusion: (Elevation increase of Kelani and Gin Barrages)
Storage Reservoirs have limited Capacity and no expansions
have been done in the recent past
Groundwater is pumped from deep aquifers. Wells are designed
accordingly but the monitoring of the aquifer status other than
the quality of water is not done during extraction (in any of the
schemes)
Demand for Domestic and Industrial Uses are calculated based
on Daily Demand and the availability of sufficient storage until
replenished
Mid Night Noon 6 PM
Training Needs:
• Hydrological Assessment of the Source Watersheds
and Data Collection Needs
• Source Area Engineering and Management
• Basin Planning with adequate inputs from other
sectors to identify the availability for expansions
• System study techniques to identify alternative
solutions (to incorporate supplementary storage to
overcome dry season problems etc)
• Groundwater Aquifer Modelling and Data Collection
needs
• Groundwater enrichment developments and
infrastructure
Urban Water Supply
Water Demand for Pipe Borne water
NWSDB has done several studies in specific areas and
identified that the unaccounted for water is approximately 40 -
45%
It is introducing demand management techniques. In some
areas introducing GIS based models along with metering to
identify loss zones for remedying
Identified that rainwater harvesting should be promoted
No studies are done to determine the actual demand rates or to
identify the optimum allocations for system designs
Pipe borne water at doorstep is available to only 29% of the
population
Training Needs:
• Demand assessment techniques
• Incorporation of land occupancy variations/spatial
variations for the pipe network modeling to arrive at
better estimates
• Spatial Database or GIS based design techniques
for the establishment of such units to carryout
proper assessments in a changing environment
• Assessment of System Losses through
measurements and modelling with sensitivity
analysis to embark on better water management
• Houses of mostly low income – under water
• Roads become impassable – Disrupts economic activities
• Causes traffic congestions – Accidents, Vehicle Maintenance
• Pedestrians in a great difficulty –Splashes from passing by
vehicles, Water Pools to walk in
• Water logging and poor drainage –deteriorate road surface -
huge repair costs
• Mosquito Breeding, overflow of septic tanks, dirty drainages –
causes health hazards
• Urban Area Flooding
Being in the wet zone of Sri Lanka Most Urban Centers
are experiencing rain almost throughout the year, this
is a bigger concern than the water supply. (Urban
Status-Flooding and Drainage –intolerable)
The identified causes for urban flooding -
indiscriminate filling of lowlands, Alteration of
Drainage Paths, increase of impervious areas, and
inadequate drainage designs, and lack of adequate
legislation and commitment
Being an island, in Sri Lanka, urban storm water
management is vital because most of our urban
centres are either located in a river valley, in or close
proximity to an estuary, or by the side of a lake.
In Colombo the water and marshy
wetlands had been nearly 52% but
presently the water bodies and remaining
marshes occupy only approximately 5% of
the land area.
The Hydrological assessments are done with models
which have not been verified or having less than
minimum verifications
There are no gauging stations with reliable stage
discharge curves
Except on a project wise, short term basis the RF is
not gauged at a spatial resolution satisfactory for
urban hydrological models
Legislation covers only large scale developments:
cumulative effects are ignored.
Flood Detention and Retention concepts are still
with the engineers awaiting acceptance of the
politicians
Training Needs:
• Urban Hydrology and Drainage issues in low lying and
downstream controlled situations
• Floodplain Management-Flood Retention and
Detention concepts, Design of infiltration facilities etc.
• Methods for Public awareness increase and public
corporation achievement
• Development of Spatially distributed models using GIS
to identify impacts of filling and encroachments
• Network Designs-Establish proper stations RF & SF
gauging
• Compute and Identify Appropriate Design Storms
HIGHLY
POLLUTED
CANALS
Kittampahuw
a Ela
2 Water sampling point
Locations of Continuous Monitoring of Water
Quality & Levels
23
1
9
8
7
6
4
2
1
Sea
NORTH LOCK OUTLET TO KELANI
5
Training Needs:
• Water Quality modelling in GIS and identification of Dilution
factors – Lowflow periods, consequences with floods
• Community Awareness of Waste and Wastewater Disposal
• Effects of Disposal on Hydrology and water quality
• Ecological Modelling to Identify alternatives solutions to
improve already polluted water bodies
• Design and maintenance of wetlands for water quality
improvement and flood detention and retention
• Eco Tourism and river environment improvement concepts
• Benefits for low income groups and avenues for income
generation
Governance Issue
The Urban Development Authority under the
Ministry of Urban Public Utilities is vested with the
task of integrated planning and implementation of
economic, social and physical development of
urban development areas in the country, which are
specific areas declared by the Ministry
UDA is vested with very strong powers
Governance Issue
Water Supply
NWSDB is responsible for 95% of the Supply
Two Ministries + Two Authorities + Two Boards and
one Department, are involved in the Urban Water
Supply and Sanitation services – interrelation between
them is complex
The NWSDB has identified funding problems and
therefore promotes private sector investments
It has already been identified to establish an
industry specific water regulator
To ensure better water quality, it has been
identified to promote a “industry citing policy” in
relation to water intakes
There isn’t a clear cut policy on water sharing
between different competing agencies
Governance Issue
Storm Water and Drainage
SLLRDC – Sri Lanka land reclamation and
development corporation is the main agency.
UDA and the Agrarian Services corporation also
play major roles
CEA – the regulating authority
ID – Flood forecasting and fighting
Local Authorities such as Municipal councils,
provincial councils, Urban Councils are also
responsible for the land use and storm water
management
Issues and constraints
Unclear responsibilities among state agencies
for Storm water drainage works. (Different
agencies have different areas of jurisdiction
which are unclear)
Lack of an authorised landuse plan for urban
centers – case by case gives rise to malpractices
Malfunction of the Regulation system for low
land development
-No comprehensive statute for land use
regulation
-No proper evaluation system for land filling
proposals
-No guidelines backed by studies to identify
detention needs
Training Needs
Institutional needs and policy framework for good
governance
Public and State corporation for sustainable
environmental planning and management of storm
water infrastructure
Methods of identifying scientific studies to support
policy formulation
Conclusions
For Sri Lanka it is important that the water supply,
storm water management and water quality
training is strengthened to ensure a sustainable
urban environment.
The urban hydrology along with analysis
techniques through available models should be
taught incorporating the aspect of both spatial and
temporal variability
The training would have to incorporate a component
on group work case studies for practicing water
professionals to identify appropriate solutions.
The training should attempt to incorporate the
techniques of working with the public not only at the
implementation of solutions but also for data
collection, selection of decision making criteria and
making guidelines
Training could include short term training (seminar
type) on new methods, Techniques, Technology –
awareness (senior, middle, technical)
Training could have short term, hands on training
for middle and technical personnel
Collaborative (industry experience) postgraduate
degree programs with state and other funding
assistance (for the young and the enthusiastic)
have to be the foundation