HydroBASINS lev08 watershed · #2080033620
Bassin de Ustadelva
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 7 administrative regions : Asker, Bærum, Frogn, Hurum, Lier +2
Sub-basin area
456,2km²
Upstream area
456,2km²
Discharge
2,3m³/s
Mean elev.
153m
Administrative coverage
7 dept-equivalent regions (GADM L2)
- 162.6 km²35.4% of basin
- 115.3 km²25.1% of basin
- 95.7 km²20.9% of basin
- 27.0 km²5.9% of basin
- 19.0 km²4.1% of basin
- 5.8 km²1.3% of basin
- 0.7 km²0.2% of basin
30 intersecting protected areas
Skaugumåsen, Semsvannet og Hagahogget
IUCN Not ReportedEmerald Network
7.00 km² overlap
Semsvannet
IUCN VProtected Landscape
4.63 km² overlap
Søndre Håøya
IUCN IaNature Reserve
3.71 km² overlap
Søndre Håøya
IUCN Not ReportedEmerald Network
3.71 km² overlap
Tofteskogen
IUCN IaNature Reserve
2.98 km² overlap
Sandungåsen
IUCN IaNature Reserve
2.62 km² overlap
Blåfjell
IUCN IaNature Reserve
1.93 km² overlap
Furuåsen og Hagahogget
IUCN IaNature Reserve
1.84 km² overlap
Nordre Skaugumsåsen
IUCN IaNature Reserve
1.26 km² overlap
21 more protected areassorted by overlap area
Geitmyråsen
IUCN IaNature Reserve
1.09 km² overlap
Haraldsfjellet
IUCN IaNature Reserve
0.99 km² overlap
Gråøya
IUCN IaNature Reserve
0.72 km² overlap
Skaugumsåsen og Åstad
IUCN IaNature Reserve
0.69 km² overlap
Løkeneshalvøya
IUCN VProtected Landscape
0.62 km² overlap
Ramsås
IUCN IaNature Reserve
0.58 km² overlap
Nesøytjern
IUCN IaNature Reserve
0.50 km² overlap
Nesøytjern
IUCN Not ReportedEmerald Network
0.50 km² overlap
Sandbukta-Østnestangen
IUCN IaNature Reserve
0.48 km² overlap
Vassmyråsen
IUCN IaNature Reserve
0.41 km² overlap
Solfjellåsene
IUCN IaNature Reserve
0.29 km² overlap
Linnesstranda
IUCN Not ReportedEmerald Network
0.28 km² overlap
Linnesstranda
IUCN IaNature Reserve
0.28 km² overlap
Ramsåsen
IUCN Not ReportedEmerald Network
0.27 km² overlap
Løkenesskogen
IUCN IaNature Reserve
0.26 km² overlap
Holtnesdalen
IUCN Not ReportedEmerald Network
0.26 km² overlap
Holtnesdalen
IUCN IaNature Reserve
0.26 km² overlap
Mølen
IUCN IaNature Reserve
0.22 km² overlap
Bjerkås
IUCN Not ReportedEmerald Network
0.21 km² overlap
Bjerkås
IUCN IaNature Reserve
0.21 km² overlap
Oppsjømyrene
IUCN IaNature Reserve
0.19 km² overlap
Computed live · GADM 4.1 × HydroBASINS lev08 × WDPA · cached after first hit.
Species present
13 783 distinct species · 450 907 observations
Source: GBIF Occurrence snapshot 2026-05-01.
Ecological tissue
Sample of 35 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 Ustadelva : 23 espèces dont 1 patrimoniale (LR IUCN CR/EN/VU) reliées par 89 interactions GloBI sur 7 types (connectance 15.0%, filtre Serrano α=0.2). 12 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°
5,7°C
Annual rain
755mm
Moisture idx (CMI)
0,29
Runoff
652mm/an
PET
533mm
AET
442mm
Mean slope
6,8°
Water table
312cm
Forest
74%
Crops
12%
Urban
14%
Protected
5%
HydroATLAS BasinATLAS v10 (Linke et al. 2019) · HydroBASINS lev08 (Lehner & Grill 2013)