HydroBASINS lev08 watershed · #2080031860
Bassin de Trosaån
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 6 administrative regions : Flen, Gnesta, Nyköping, Strängnäs, Södertälje +1
Sub-basin area
557,6km²
Upstream area
557,6km²
Discharge
1,63m³/s
Mean elev.
44m
Administrative coverage
6 dept-equivalent regions (GADM L2)
- 351.7 km²62.7% of basin
- SödertäljeStockholm · Sweden116.6 km²20.8% of basin
- 66.9 km²11.9% of basin
- 21.6 km²3.9% of basin
- 1.8 km²0.3% of basin
- 0.2 km²0.0% of basin
30 intersecting protected areas
2002405 Tullgarn
IUCN VNature Conservation Area
3.88 km² overlap
Tullgarn södra
IUCN Not ReportedSpecial Areas of Conservation (Habitats Directive)
3.85 km² overlap
Tullgarn södra
IUCN VNatura 2000 SCI
3.85 km² overlap
Tullgarn södra
IUCN VNatura 2000 SPA
3.85 km² overlap
Tullgarn södra
IUCN Not ReportedSpecial Protection Area (Birds Directive)
3.85 km² overlap
2057621 Uddaberget
IUCN IaNature Reserve
3.74 km² overlap
Marvikarna
IUCN IIINatura 2000 SPA
2.13 km² overlap
Marvikarna
IUCN IIINatura 2000 SCI
2.13 km² overlap
Marvikarna
IUCN Not ReportedSpecial Protection Area (Birds Directive)
2.13 km² overlap
21 more protected areassorted by overlap area
Marvikarna
IUCN Not ReportedSpecial Areas of Conservation (Habitats Directive)
2.13 km² overlap
Nature Reserve
1.55 km² overlap
2013371 Stora Alsjön
IUCN IaNature Reserve
1.46 km² overlap
Stora Alsjön
IUCN Not ReportedSpecial Areas of Conservation (Habitats Directive)
1.29 km² overlap
Stora Alsjön
IUCN IaNatura 2000 SCI
1.29 km² overlap
2026949 Ekeby
IUCN IaNature Reserve
0.98 km² overlap
Stora Envättern
IUCN Not ReportedSpecial Areas of Conservation (Habitats Directive)
0.80 km² overlap
Nature Reserve
0.80 km² overlap
Stora Envättern
IUCN IaNatura 2000 SCI
0.80 km² overlap
2026951 Lugnet
IUCN IaNature Reserve
0.76 km² overlap
2050058 Ehrendal Norra
IUCN IaNature Reserve
0.74 km² overlap
2040976 Björndalsbergen
IUCN IaNature Reserve
0.69 km² overlap
2001872 Marvikarna
IUCN IIINature Reserve
0.58 km² overlap
2024410 Tomtaklintskogen
IUCN IaNature Reserve
0.52 km² overlap
2047941 Långaedet
IUCN IaNature Reserve
0.50 km² overlap
Skogstorp
IUCN IaNatura 2000 SCI
0.49 km² overlap
Skogstorp
IUCN Not ReportedSpecial Areas of Conservation (Habitats Directive)
0.49 km² overlap
Tussmötet
IUCN IaNatura 2000 SCI
0.49 km² overlap
2014847 Tussmötet
IUCN IaNature Reserve
0.49 km² overlap
Tussmötet
IUCN Not ReportedSpecial Areas of Conservation (Habitats Directive)
0.49 km² overlap
2002932 Hårbyskogen
IUCN IaNature Reserve
0.49 km² overlap
Computed live · GADM 4.1 × HydroBASINS lev08 × WDPA · cached after first hit.
Species present
7 758 distinct species · 427 381 observations
Source: GBIF Occurrence snapshot 2026-05-01.
Ecological tissue
Sample of 27 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 Trosaån : 18 espèces dont 1 patrimoniale (LR IUCN CR/EN/VU) reliées par 87 interactions GloBI sur 5 types (connectance 23.0%, filtre Serrano α=0.2). 10 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°
6,6°C
Annual rain
544mm
Moisture idx (CMI)
-0,06
Runoff
184mm/an
PET
576mm
AET
417mm
Mean slope
2,6°
Water table
207cm
Forest
73%
Crops
13%
Urban
1%
Protected
3%
HydroATLAS BasinATLAS v10 (Linke et al. 2019) · HydroBASINS lev08 (Lehner & Grill 2013)