HydroBASINS lev08 watershed · #4080049020
Bassin de Weras Ganga
A watershed (drainage basin) is not a body of water — it is the land area where rainfall converges towards a single river that eventually reaches the sea (or an endorheic basin). Boundaries follow ridgelines.
Crosses 15 administrative regions : Bandaragama, Colombo, Dehiwala-Mount Lavinia, Homagama, Horana +10
Sub-basin area
310,4km²
Upstream area
310,4km²
Discharge
1,26m³/s
Mean elev.
17m
Administrative coverage
15 dept-equivalent regions (GADM L2)
- 67.0 km²21.7% of basin
- 61.5 km²19.9% of basin
- 34.6 km²11.2% of basin
- 30.9 km²10.0% of basin
- Dehiwala-Mount LaviniaColombo · Sri Lanka21.7 km²7.0% of basin
- 20.0 km²6.5% of basin
- MaharagamaColombo · Sri Lanka16.5 km²5.4% of basin
- BandaragamaKalutara · Sri Lanka14.5 km²4.7% of basin
7 moreFull L2 list
- Colombo11.2 km² · 3.6%
- Thimbirigasyaya7.1 km² · 2.3%
- Kalutara6.5 km² · 2.1%
- Padukka3.1 km² · 1.0%
- Sri Jayawardanapura Kotte2.4 km² · 0.8%
- Kaduwela0.2 km² · 0.1%
- Wattala0.0 km² · 0.0%
2 intersecting protected areas
Bolgoda EPA
IUCN VEnvironmental Protection Area (EPA)
14.98 km² overlap
Sri Jayawardanapura
IUCN IVSanctuary
3.79 km² overlap
Computed live · GADM 4.1 × HydroBASINS lev08 × WDPA · cached after first hit.
Species present
1 148 distinct species · 118 760 observations
Source: GBIF Occurrence snapshot 2026-05-01.
Ecological tissue
Sample of 29 species (selected proportionally per kingdom among those with at least one documented interaction here) to keep the graph readable. Hover for details, click to explore the full ecosystem of a species.
ℹ️ The territory contains many more species than displayed and all their documented interactions: the graph is intentionally the structural skeleton (top-N species by composite local score, edges filtered by Serrano 2009 disparity filter α=0.2).
Indicateurs du tissu écologique
Tissu écologique de Bassin de Weras Ganga : 25 espèces dont 2 patrimoniales (LR IUCN CR/EN/VU) reliées par 34 interactions GloBI sur 3 types (connectance 8.4%, filtre Serrano α=0.2). 4 bulles taxonomiques (cascade genre/famille GloBI, ≥3 espèces).
Comparaison sur la connectance du réseau local complet vs distribution nationale (toutes les communes françaises).
Hydroclimate (BasinATLAS lev08)
Mean T°
26,9°C
Annual rain
2 834mm
Moisture idx (CMI)
0,49
Runoff
1 291mm/an
PET
1 426mm
AET
1 370mm
Mean slope
1,4°
Water table
47cm
Forest
0%
Crops
48%
Urban
98%
Protected
2%
HydroATLAS BasinATLAS v10 (Linke et al. 2019) · HydroBASINS lev08 (Lehner & Grill 2013)