HydroBASINS lev08 watershed · #2080481380
Bassin de l'Oust
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 : Côtes-d'Armor, Morbihan
Sub-basin area
428,9km²
Upstream area
428,9km²
Discharge
9,01m³/s
Mean elev.
164m
Administrative coverage
Hydrographic chain
▼ Drains into
▲ Receives from 0 basins
Source / headwater (no upstream basin)
2 dept-equivalent regions (GADM L2)
- 335.4 km²78.0% of basin
- 94.8 km²22.0% of basin
33 communes (GADM L5)Available for FRA, RWA
- Loudéac71.43 km²87% commune
- Merléac27.83 km²91% commune
- Trévé26.47 km²100% commune
- Allineuc24.56 km²100% commune
- Saint-Martin-des-Prés20.60 km²100% commune
- Rohan19.83 km²84% commune
- Bréhan19.80 km²38% commune
- Saint-Caradec18.61 km²83% commune
- La Harmoye17.09 km²94% commune
- Crédin15.94 km²48% commune
- Saint-Thélo14.70 km²100% commune
- Gueltas14.65 km²70% commune
- Saint-Gonnery14.55 km²89% commune
- Hémonstoir13.82 km²98% commune
- Le Bodéo10.04 km²100% commune
- Le Quillio9.89 km²61% commune
- Le Haut-Corlay9.84 km²38% commune
- Saint-Hervé9.12 km²90% commune
- L'Hermitage-Lorge8.63 km²22% commune
- Saint-Barnabé8.31 km²36% commune
- La Motte8.09 km²18% commune
- Grâce-Uzel7.16 km²88% commune
- Pleugriffet7.08 km²18% commune
- Uzel6.96 km²100% commune
- Saint-Maudan6.72 km²100% commune
- Saint-Gilles-Vieux-Marché4.25 km²19% commune
- Corlay3.28 km²23% commune
- Saint-Guen3.24 km²18% commune
- Croixanvec2.91 km²48% commune
- Lanfains2.71 km²12% commune
- Saint-Mayeux2.00 km²6% commune
- Saint-Bihy0.07 km²1% commune
- Saint-Connec0.00 km²0% commune
1 intersecting protected areas
Forêt de Lorge, landes de Lanfains, cime de Kerchouan
IUCN Not ReportedSpecial Areas of Conservation (Habitats Directive)
1.32 km² overlap
Computed live · GADM 4.1 × HydroBASINS lev08 × WDPA · cached after first hit.
Species present
1 474 distinct species · 38 040 observations
Source: GBIF Occurrence snapshot 2026-05-01.
Ecological tissue
Sample of 32 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'Oust : 19 espèces dont 2 patrimoniales (LR IUCN CR/EN/VU) reliées par 87 interactions GloBI sur 6 types (connectance 14.6%, filtre Serrano α=0.2). 16 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°
10,7°C
Annual rain
872mm
Moisture idx (CMI)
0,20
Runoff
663mm/an
PET
699mm
AET
545mm
Mean slope
2,8°
Water table
196cm
Forest
1%
Crops
72%
Urban
2%
Protected
0%
HydroATLAS BasinATLAS v10 (Linke et al. 2019) · HydroBASINS lev08 (Lehner & Grill 2013)