HydroBASINS lev08 watershed · #2080021730
Bassin du Guyoult
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 3 administrative regions : Côtes-d'Armor, Ille-et-Vilaine, Manche
Sub-basin area
627,3km²
Upstream area
627,3km²
Discharge
2,24m³/s
Mean elev.
35m
Administrative coverage
3 dept-equivalent regions (GADM L2)
- 591.0 km²93.9% of basin
- 12.0 km²1.9% of basin
- 0.1 km²0.0% of basin
49 communes (GADM L5)Available for FRA, RWA
- Saint-Malo38.04 km²100% commune
- Roz-sur-Couesnon31.28 km²93% commune
- Saint-Méloir-des-Ondes29.25 km²100% commune
- Miniac-Morvan27.60 km²87% commune
- Mont-Dol26.56 km²100% commune
- Saint-Broladre25.46 km²100% commune
- Bonnemain24.98 km²100% commune
- Epiniac24.13 km²100% commune
- Baguer-Morvan23.69 km²100% commune
- La Boussac21.82 km²100% commune
- Plerguer20.49 km²100% commune
- Saint-Pierre-de-Plesguen19.78 km²67% commune
- Saint-Père19.21 km²100% commune
- Saint-Coulomb19.01 km²100% commune
- Roz-Landrieux18.29 km²100% commune
- Baguer-Pican16.12 km²100% commune
- Dol-de-Bretagne15.74 km²100% commune
- Cherrueix14.86 km²100% commune
- La Fresnais14.43 km²100% commune
- Cancale13.45 km²100% commune
- Broualan12.89 km²100% commune
- Le Tronchet10.95 km²100% commune
- Hirel10.63 km²100% commune
- Saint-Jouan-des-Guérets9.24 km²100% commune
- La Gouesnière9.12 km²100% commune
- Combourg8.88 km²14% commune
- Saint-Georges-de-Gréhaigne7.54 km²62% commune
- Saint-Marcan7.26 km²100% commune
- Meillac7.07 km²21% commune
- Beauvoir6.74 km²38% commune
- Cuguen6.57 km²27% commune
- Lanhélin6.47 km²100% commune
- Saint-Guinoux6.35 km²100% commune
- Tressé5.45 km²100% commune
- Le Mont-Saint-Michel5.23 km²52% commune
- Saint-Suliac5.01 km²100% commune
- Lourmais5.01 km²72% commune
- Trans-la-Forêt4.07 km²27% commune
- Lillemer3.71 km²100% commune
- Le Vivier-sur-Mer3.05 km²100% commune
- Saint-Benoît-des-Ondes3.04 km²100% commune
- Pleine-Fougères2.83 km²8% commune
- Trémeheuc2.82 km²44% commune
- La Ville-ès-Nonais2.77 km²65% commune
- Sains2.76 km²27% commune
- Pleugueneuc1.60 km²6% commune
- Châteauneuf-d'Ille-et-Vilaine1.37 km²98% commune
- Bazouges-la-Pérouse0.31 km²1% commune
- Pleudihen-sur-Rance0.14 km²1% commune
20 intersecting protected areas
Regional Nature Park
147.77 km² overlap
Baie du Mont Saint-Michel
IUCN Not ReportedSpecial Protection Area (Birds Directive)
83.66 km² overlap
Baie du Mont Saint-Michel
IUCN Not ReportedWetland of International Importance (Ramsar Site)
83.03 km² overlap
Baie du Mont Saint-Michel
IUCN Not ReportedSpecial Areas of Conservation (Habitats Directive)
29.54 km² overlap
Côte de Cancale à Paramé
IUCN Not ReportedSpecial Areas of Conservation (Habitats Directive)
13.12 km² overlap
Land acquired by Conservatoire du Littoral (national seaside and lakeside conservancy)
10.66 km² overlap
Estuaire de la Rance
IUCN Not ReportedSpecial Areas of Conservation (Habitats Directive)
9.66 km² overlap
Les Cordons coquilliers de la Baie du Mont Saint-Michel
IUCN Not ReportedGeotope Protection Order
1.21 km² overlap
Chausey
IUCN Not ReportedSpecial Protection Area (Birds Directive)
0.67 km² overlap
11 more protected areassorted by overlap area
Anse du verger
IUCN IVLand acquired by Conservatoire du Littoral (national seaside and lakeside conservancy)
0.56 km² overlap
Chausey
IUCN Not ReportedSpecial Areas of Conservation (Habitats Directive)
0.42 km² overlap
Ile besnard
IUCN IVLand acquired by Conservatoire du Littoral (national seaside and lakeside conservancy)
0.22 km² overlap
Pointe de la varde
IUCN IVLand acquired by Conservatoire du Littoral (national seaside and lakeside conservancy)
0.18 km² overlap
Pointe du meinga
IUCN IVLand acquired by Conservatoire du Littoral (national seaside and lakeside conservancy)
0.15 km² overlap
Iles des landes
IUCN IVLand acquired by Conservatoire du Littoral (national seaside and lakeside conservancy)
0.08 km² overlap
Land acquired by Conservatoire du Littoral (national seaside and lakeside conservancy)
0.02 km² overlap
Ilôts Notre-Dame et Chevret
IUCN Not ReportedSpecial Protection Area (Birds Directive)
0.01 km² overlap
La Vallée de la Rance
IUCN Not ReportedGeotope Protection Order
0.01 km² overlap
Biotope Protection Order
0.00 km² overlap
Moulin De La Higourdais
IUCN IVBiotope Protection Order
0.00 km² overlap
Computed live · GADM 4.1 × HydroBASINS lev08 × WDPA · cached after first hit.
Species present
5 804 distinct species · 333 301 observations
Source: GBIF Occurrence snapshot 2026-05-01.
Ecological tissue
Sample of 34 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 du Guyoult : 14 espèces reliées par 184 interactions GloBI sur 6 types (connectance 13.9%, filtre Serrano α=0.2). 38 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°
11,3°C
Annual rain
734mm
Moisture idx (CMI)
-0,01
Runoff
527mm/an
PET
740mm
AET
542mm
Mean slope
1,2°
Water table
98cm
Forest
2%
Crops
64%
Urban
7%
Protected
0%
HydroATLAS BasinATLAS v10 (Linke et al. 2019) · HydroBASINS lev08 (Lehner & Grill 2013)