Country Report - GEOSS/AWCI demonstration projects
SRI LANKA

S. B. Weerakoon
University of Peradeniya
Sri Lanka

The 3rd GEOSS Asian Water Cycle Symposium
Beppu, Japan, 2-4 November 2007

Issues in three basins

Kaluganga basin (2720 sq km)
FloodsMahaweli basin (10450 sq.km)
Irrigation water management

Walawe basin (2470 sq.km)
Irrigation water management

Sri Lankan topography

 significant spatial variation of climate, r/f, geology, soil, land cover,…

Kaluganga BasinKaluganga Basin
Magnitude of the annual flow volume
4000 MCM
Catchments area2690 sq. km
Average annual rainfall
4000 mm (3000-5000mm)
Elevation up to2250 m
River length
129 kmLength to Ratnapura
65 km
Major floods to Ratnapura
20mMSLYear

Water level/(m MSL)

1913

24.6

1940

24.3

1941

24.4

1947

24.8

2003

23.7

Principal Meteorological Stations
Agrometeorological Stations
Raingauge Stations

Streams

Meteorological Station Network

Data in Demonstration Basins
Reference basin

Sri Lanka Mahaweli
Basin

METADATA (River Basin
Desccription)olol(06 45 N, 80 40 E toLocation (longitude andolol
lattitude extent)
08 30 N, 81 15 E)
Catchment outlet longitude 08deg30min N,and latitude
81deg15min E
Catchment area
10448 sqkm
Number of MOLTS points
in the basin
MOLTS point1 longitude
07deg20min N,and latitude
80deg38min E
MOLTS point1 elevation
477 meters

Sri Lanka Kaluganga
Basinolo

Sri Lanka Nilwalaganga Basinl(06 25 N, 80 00 E toolol
06 50 N, 80 40 E)
06deg35min N,80deg00min E
2719 sqkm
1olololol(06 00 N, 80 25 E to 06 30 N, 80 45 E)
06deg00min N, 80deg30min E
971 sqkm
1106deg41min N,80deg24min E34 meters

06deg09min N, 80deg25min E
25 meters

MOLTS point X
Basin Contacts (Name,office address, phone, fax,email)Available
Basin Maps
Available
Basin Pictures
Available
River Network Maps
Soil Maps and Soil
Characteristics
Available

Available
Available
Available

Available
Available
Available

Available

Available

Land Use Maps andVegetation Characteristics Available

Available

Available

River Constructions (dams,weirs, etc.) - type, location(longitude, latitude)
Available

Available

Available

Data in Demonstration Basins
River Constructions (dams,weirs, etc.) - type, location(longitude, latitude)
Available
OBSERVATION DATA HYDROLOGICAL
Streamflow
Available
Reservoir (Water level,Outflow)
Available
Others - please specify(each data type on a singleline)
OBSERVATION DATA SUB-SURFACE
Soil Temperature

Available

Available

Available

Available

Available

Available

Available

Available

Unavailable

OBSERVATION DATA SURFACE
Air Temperature
Available
Available
Unavailable
Humidity
Available
Available
Unavailable
Wind
Available
Available
Unavailable
Pressure
Available
Available
Unavailable
Precipitation
Available
Available
Available
Evaporation
Available
Available
Available
olol
Radar and Radiosonde observations are available in Colombo (06 54 N, 79 85 E ) but outside of the three selected basinsDemonstration Project• Data preparation for DHM applications– Kaluganga basin hydrology details• Daily time series data of stream flow at fivelocations (two years)• River cross sections at 5 locations• Daily rainfall time series at 10 locations– GIS data DEM, landuse, stream network inthe basin

Rainfall downscaling for the basin

Using Global Climate Model and WRF
rainfall forecasting was downscaled to cover thedemonstration project region
The reliability of predictions need to be verified andappropriate model parameters need to be selected forindividual basins - preliminary results.

Domains
43 x 43 in each
three nests of27, 9, 3 km
square cellsizes
ref_lat = 7.17
ref_lon = 80.763

Simulation Control Parameters• start_date = 2007-11-01_00:00:00• end_date = 2007-11-01_12:00:00• time_step= 120• interval_seconds for gfs data = 10800•
history_interval= 10Capacity building• Training Workshops
Hydrological Modelling Workshop
Computational Hydraulic Modelling Workshop

Resource Persons:From the University of Peradeniya,
Visiting Scholars from abroad• Participation
30 engineers in water sector in Sri Lanka

Devon waterfall( Upper Kotmale Subbasin)

Walawe Basin
Catchments area
Average annual rainfall

2690 sq. km
1000-3000 mm

Paddy

Streams

Mahaweli Basin
Catchments area
Average annual rainfall

Streams

10450 sq. km
1500-5000 mm

Paddy