HydroBASINS lev08 watershed · #2080257080
Bassin de Nidelva
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 : Arendal, Birkenes, Froland, Grimstad, Tvedestrand +2
Sub-basin area
577,7km²
Upstream area
3 714,8km²
Discharge
94,87m³/s
Mean elev.
225m
Administrative coverage
Hydrographic chain
▼ Drains into
▲ Receives from 2 basins
- Bassin de Gjøv506 km²
- Bassin de Nidelva264 km²
7 dept-equivalent regions (GADM L2)
- 285.3 km²49.1% of basin
- 240.9 km²41.5% of basin
- 27.9 km²4.8% of basin
- 22.4 km²3.9% of basin
- 4.0 km²0.7% of basin
- 0.3 km²0.1% of basin
- 0.0 km²0.0% of basin
18 intersecting protected areas
Urdvatn og Kallingshei
IUCN IaNature Reserve
18.10 km² overlap
Solbergheia
IUCN IaNature Reserve
7.23 km² overlap
Hovdefjell
IUCN IaNature Reserve
2.38 km² overlap
Romeheia
IUCN IaNature Reserve
2.13 km² overlap
Eikelidalen
IUCN IaNature Reserve
1.97 km² overlap
Jomåsknutene
IUCN IaNature Reserve
1.16 km² overlap
Haugsjåknipen
IUCN Not ReportedEmerald Network
0.88 km² overlap
Haugsjåknipen
IUCN IaNature Reserve
0.88 km² overlap
Åslandsøya og Kjeøya
IUCN IaNature Reserve
0.58 km² overlap
9 more protected areassorted by overlap area
Stuvåna
IUCN IaNature Reserve
0.48 km² overlap
Styggetjønnåsen
IUCN IaNature Reserve
0.43 km² overlap
Lillestø
IUCN IaNature Reserve
0.25 km² overlap
Blesehelleren
IUCN IaNature Reserve
0.13 km² overlap
Bjellandshaugane
IUCN IaNature Reserve
0.12 km² overlap
Bjellandshaugane
IUCN Not ReportedEmerald Network
0.12 km² overlap
Eikåsen
IUCN IaNature Reserve
0.04 km² overlap
Lauvåsen
IUCN IaNature Reserve
0.01 km² overlap
Lauvåsen
IUCN Not ReportedEmerald Network
0.01 km² overlap
Computed live · GADM 4.1 × HydroBASINS lev08 × WDPA · cached after first hit.
Species present
4 316 distinct species · 65 915 observations
Source: GBIF Occurrence snapshot 2026-05-01.
Ecological tissue
Sample of 33 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 Nidelva : 20 espèces reliées par 97 interactions GloBI sur 6 types (connectance 16.3%, filtre Serrano α=0.2). 15 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°
5,9°C
Annual rain
1 085mm
Moisture idx (CMI)
0,56
Runoff
917mm/an
PET
475mm
AET
444mm
Mean slope
6,5°
Water table
300cm
Forest
91%
Crops
2%
Urban
0%
Protected
3%
HydroATLAS BasinATLAS v10 (Linke et al. 2019) · HydroBASINS lev08 (Lehner & Grill 2013)