HydroBASINS lev08 watershed · #2080492740
Bassin de l'Isac
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 2 administrative regions : Loire-Atlantique, Morbihan
Sub-basin area
724,5km²
Upstream area
724,7km²
Discharge
11,31m³/s
Mean elev.
39m
Administrative coverage
Hydrographic chain
▼ Drains into
▲ Receives from 0 basins
Source / headwater (no upstream basin)
2 dept-equivalent regions (GADM L2)
- 719.1 km²99.0% of basin
- 7.4 km²1.0% of basin
33 communes (GADM L5)Available for FRA, RWA
- Blain102.72 km²100% commune
- Plessé100.63 km²96% commune
- Fay-de-Bretagne63.83 km²99% commune
- Héric60.24 km²81% commune
- Saffré55.74 km²95% commune
- Le Gâvre49.58 km²92% commune
- Guenrouet43.79 km²62% commune
- Vay35.97 km²98% commune
- Notre-Dame-des-Landes35.93 km²97% commune
- Fégréac24.11 km²54% commune
- Abbaretz23.95 km²39% commune
- La Grigonnais21.64 km²100% commune
- Sévérac21.00 km²93% commune
- Puceul19.71 km²100% commune
- Malville13.90 km²44% commune
- Bouvron11.36 km²24% commune
- La Chevallerais10.84 km²100% commune
- Nozay8.73 km²15% commune
- Théhillac7.37 km²52% commune
- Nort-sur-Erdre3.78 km²6% commune
- Grandchamps-des-Fontaines2.52 km²7% commune
- Joué-sur-Erdre1.70 km²3% commune
- Marsac-sur-Don1.65 km²6% commune
- Vigneux-de-Bretagne1.09 km²2% commune
- Savenay1.08 km²4% commune
- Saint-Gildas-des-Bois1.05 km²3% commune
- Missillac0.93 km²2% commune
- Guémené-Penfao0.80 km²1% commune
- Quilly0.33 km²2% commune
- Treillières0.22 km²1% commune
- Avessac0.18 km²0% commune
- Le Temple-de-Bretagne0.11 km²6% commune
- Rieux0.03 km²0% commune
7 intersecting protected areas
Forêt de Gâvre
IUCN Not ReportedSpecial Protection Area (Birds Directive)
40.20 km² overlap
Marais de Vilaine
IUCN Not ReportedSpecial Areas of Conservation (Habitats Directive)
11.85 km² overlap
Brière
IUCN VRegional Nature Park
0.77 km² overlap
Biotope Protection Order
0.10 km² overlap
Le Bois Gouet
IUCN Not ReportedGeotope Protection Order
0.00 km² overlap
Le Bois Gouet
IUCN IVGeotope Protection Order
0.00 km² overlap
bocage des rives de l\'isac
IUCN IVLand acquired by a regional conservatory of natural areas
0.00 km² overlap
Computed live · GADM 4.1 × HydroBASINS lev08 × WDPA · cached after first hit.
Species present
4 660 distinct species · 76 792 observations
Source: GBIF Occurrence snapshot 2026-05-01.
Ecological tissue
Sample of 45 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 l'Isac : 40 espèces dont 1 patrimoniale (LR IUCN CR/EN/VU) + 5 bulles famille, 75 interactions GloBI documentées sur 4 types (connectance 7.6%, filtre Serrano α=0.2). Les 5 bulles regroupent des espèces visuellement absorbées par famille (≥3 espèces visibles).
Comparaison sur la connectance du réseau local complet vs distribution nationale (toutes les communes françaises).
Hydroclimate (BasinATLAS lev08)
Mean T°
11,4°C
Annual rain
778mm
Moisture idx (CMI)
-0,04
Runoff
494mm/an
PET
811mm
AET
574mm
Mean slope
1,1°
Water table
80cm
Forest
5%
Crops
63%
Urban
1%
Protected
0%
HydroATLAS BasinATLAS v10 (Linke et al. 2019) · HydroBASINS lev08 (Lehner & Grill 2013)