HydroBASINS lev08 watershed · #2080572870
Bassin de l'Alzon
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 : Gard, Lozère
Sub-basin area
1 992,4km²
Upstream area
1 992,6km²
Discharge
37,32m³/s
Mean elev.
301m
Administrative coverage
Hydrographic chain
▼ Drains into
▲ Receives from 0 basins
Source / headwater (no upstream basin)
2 dept-equivalent regions (GADM L2)
- 1630.3 km²81.7% of basin
- 366.1 km²18.3% of basin
184 communes (GADM L5)Available for FRA, RWA
- Saint-Étienne-Vallée-Française50.51 km²100% commune
- Saint-André-de-Valborgne48.42 km²99% commune
- Sainte-Anastasie44.37 km²100% commune
- Saint-Jean-du-Gard40.86 km²100% commune
- Nîmes39.93 km²25% commune
- Saint-Germain-de-Calberte38.51 km²100% commune
- Mialet31.67 km²100% commune
- Saint-Martin-de-Boubaux30.46 km²100% commune
- Les Plantiers29.58 km²96% commune
- Aigaliers27.53 km²100% commune
- Moissac-Vallée-Française27.36 km²100% commune
- Le Collet-de-Dèze26.59 km²100% commune
- Soudorgues26.00 km²99% commune
- Uzès25.56 km²100% commune
- Alès23.67 km²100% commune
- Thoiras23.29 km²100% commune
- Saint-Quentin-la-Poterie22.84 km²96% commune
- Sanilhac-Sagriès22.46 km²100% commune
- Le Pompidou22.45 km²100% commune
- Belvézet22.32 km²100% commune
- Collias21.08 km²99% commune
- Les Salles-du-Gardon20.84 km²100% commune
- Rousson20.63 km²63% commune
- Saint-Christol-lès-Alès20.45 km²100% commune
- Saint-Just-et-Vacquières20.44 km²88% commune
- Saint-Paul-la-Coste19.93 km²100% commune
- La Capelle-et-Masmolène19.72 km²80% commune
- L'Estréchure19.57 km²100% commune
- Valliguières19.42 km²99% commune
- Montaren-et-Saint-Médiers19.18 km²98% commune
- Vers-Pont-du-Gard19.16 km²100% commune
- Sainte-Cécile-d'Andorge18.98 km²99% commune
- Sainte-Croix-Vallée-Française18.21 km²100% commune
- Castillon-du-Gard18.00 km²100% commune
- Saint-Martin-de-Lansuscle17.98 km²99% commune
- Saint-Privat-de-Vallongue17.69 km²76% commune
- Vézénobres17.20 km²100% commune
- Fournès16.82 km²99% commune
- Saint-Frézal-de-Ventalon16.65 km²98% commune
- Saint-Hilaire-d'Ozilhan16.44 km²100% commune
- Saint-Privat-des-Vieux15.86 km²100% commune
- Saint-Sébastien-d'Aigrefeuille15.59 km²100% commune
- Blauzac15.34 km²100% commune
- Laval-Pradel15.21 km²86% commune
- Anduze15.00 km²100% commune
- Branoux-les-Taillades14.89 km²100% commune
- Boucoiran-et-Nozières14.67 km²100% commune
- Mons14.64 km²91% commune
- Molezon14.50 km²99% commune
- Boisset-et-Gaujac14.36 km²100% commune
- Bagard14.36 km²100% commune
- Ribaute-les-Tavernes14.22 km²100% commune
- Saint-Julien-les-Rosiers14.19 km²100% commune
- Tornac14.14 km²71% commune
- Saint-Michel-de-Dèze14.05 km²100% commune
- Montfrin14.03 km²94% commune
- Saint-Jean-du-Pin13.92 km²100% commune
- Saint-Hilaire-de-Brethmas13.91 km²100% commune
- Arpaillargues-et-Aureillac13.90 km²100% commune
- Saint-Maurice-de-Cazevieille13.59 km²100% commune
- Saint-Martin-de-Valgalgues13.52 km²100% commune
- Bassurels13.38 km²28% commune
- Saint-Mamert-du-Gard13.20 km²92% commune
- Serviers-et-Labaume12.96 km²100% commune
- Cendras12.91 km²100% commune
- Saint-Chaptes12.42 km²100% commune
- Saumane12.34 km²100% commune
- Saint-Geniès-de-Malgoirès12.03 km²100% commune
- Saint-Siffret11.89 km²100% commune
- La Grand-Combe11.78 km²97% commune
- Dions11.37 km²100% commune
- Parignargues11.26 km²100% commune
- La Calmette11.24 km²100% commune
- Gajan11.24 km²100% commune
- Flaux11.19 km²100% commune
- Soustelle10.99 km²100% commune
- Pouzilhac10.95 km²67% commune
- Générargues10.62 km²100% commune
- Saint-André-de-Lancize10.47 km²46% commune
- Barre-des-Cévennes10.47 km²30% commune
- Meynes10.43 km²61% commune
- Garrigues-Sainte-Eulalie10.37 km²100% commune
- Saint-Hilaire-de-Lavit10.23 km²100% commune
- Colognac10.20 km²82% commune
- Castelnau-Valence10.05 km²100% commune
- Baron9.99 km²100% commune
- Lasalle9.77 km²98% commune
- Saint-Maximin9.62 km²100% commune
- Collorgues9.59 km²100% commune
- Fons9.38 km²100% commune
- Lamelouze9.31 km²100% commune
- Sernhac9.06 km²100% commune
- Saint-Félix-de-Pallières8.98 km²48% commune
- Lédenon8.83 km²46% commune
- Salindres8.78 km²74% commune
- Cardet8.62 km²99% commune
- Remoulins8.41 km²100% commune
- Gabriac8.41 km²100% commune
- Sainte-Croix-de-Caderle8.13 km²100% commune
- Peyrolles8.08 km²100% commune
- La Rouvière7.83 km²100% commune
- Vallabrix7.74 km²95% commune
- Poulx7.53 km²63% commune
- Aubussargues7.45 km²100% commune
- Moussac7.40 km²100% commune
- Sauzet7.15 km²100% commune
- Argilliers7.05 km²100% commune
- Euzet7.04 km²100% commune
- Saint-Césaire-de-Gauzignan6.98 km²100% commune
- Monteils6.91 km²100% commune
- Brignon6.91 km²100% commune
- Bourdic6.90 km²100% commune
- Lézan6.87 km²76% commune
- Saint-Andéol-de-Clerguemort6.77 km²96% commune
- Saint-Jean-de-Ceyrargues6.68 km²100% commune
- Saint-Bonnet-du-Gard6.48 km²100% commune
- Méjannes-lès-Alès6.43 km²100% commune
- Saint-Hippolyte-de-Caton6.19 km²100% commune
- Saint-Dézéry6.00 km²100% commune
- Deaux5.87 km²100% commune
- Estézargues5.74 km²48% commune
- Cruviers-Lascours5.41 km²100% commune
- Cassagnoles5.40 km²100% commune
- Martignargues5.22 km²100% commune
- Saint-Bauzély5.02 km²100% commune
- Seynes4.94 km²35% commune
- Domessargues4.90 km²67% commune
- Ners4.84 km²100% commune
- Vabres4.70 km²98% commune
- Massillargues-Attuech4.69 km²79% commune
- Saint-Victor-des-Oules4.57 km²100% commune
- Saint-Bénézet4.57 km²66% commune
- Montignargues4.49 km²100% commune
- Clarensac4.38 km²30% commune
- Saint-Étienne-de-l'Olm4.18 km²100% commune
- Montagnac4.17 km²47% commune
- Saint-Hippolyte-de-Montaigu4.05 km²100% commune
- Saint-Bonnet-de-Salendrinque3.55 km²100% commune
- Foissac3.54 km²100% commune
- Saint-Julien-des-Points3.52 km²100% commune
- Saint-Maurice-de-Ventalon3.46 km²9% commune
- Maruéjols-lès-Gardon3.38 km²100% commune
- Rochefort-du-Gard3.18 km²9% commune
- Corbès3.05 km²100% commune
- Mauressargues3.03 km²52% commune
- Saint-Florent-sur-Auzonnet3.01 km²32% commune
- Lédignan2.91 km²41% commune
- La Bruguière2.89 km²17% commune
- Vebron2.64 km²4% commune
- Vallérargues2.49 km²19% commune
- Cabrières2.31 km²16% commune
- Moulézan2.03 km²18% commune
- Comps1.74 km²20% commune
- Caveirac1.45 km²9% commune
- Saint-Côme-et-Maruéjols1.41 km²11% commune
- Massanes1.38 km²100% commune
- Cassagnas1.37 km²4% commune
- Montmirat1.32 km²14% commune
- La Bastide-d'Engras1.24 km²13% commune
- Vallabrègues1.10 km²8% commune
- Portes0.99 km²7% commune
- Montpezat0.83 km²7% commune
- Servas0.51 km²5% commune
- Le Martinet0.46 km²4% commune
- Saint-Laurent-de-Trèves0.30 km²1% commune
- Chamborigaud0.29 km²2% commune
- Monoblet0.29 km²1% commune
- Saint-Jean-de-Serres0.25 km²3% commune
- Saint-Victor-la-Coste0.21 km²1% commune
- Saint-Laurent-la-Vernède0.19 km²2% commune
- Saint-Jean-de-Valériscle0.19 km²2% commune
- Notre-Dame-de-la-Rouvière0.15 km²1% commune
- Saint-Martial0.13 km²1% commune
- Théziers0.12 km²1% commune
- Vialas0.11 km²0% commune
- Crespian0.09 km²1% commune
- La Vernarède0.08 km²1% commune
- Bouquet0.05 km²0% commune
- Rousses0.04 km²0% commune
- Saint-Roman-de-Codières0.04 km²0% commune
- Valleraugue0.02 km²0% commune
- Fontarèches0.02 km²0% commune
- Les Plans0.00 km²0% commune
- Pougnadoresse0.00 km²0% commune
26 intersecting protected areas
National Park - Buffer zone/Area of adhesion
644.01 km² overlap
Vallée du Gardon de Mialet
IUCN Not ReportedSpecial Areas of Conservation (Habitats Directive)
233.19 km² overlap
Vallée du Gardon de Saint-Jean
IUCN Not ReportedSpecial Areas of Conservation (Habitats Directive)
188.18 km² overlap
Vallée du Galeizon
IUCN Not ReportedSpecial Areas of Conservation (Habitats Directive)
86.39 km² overlap
Cévennes
IUCN IINational Park - Core Area
83.95 km² overlap
Les Cévennes
IUCN Not ReportedSpecial Protection Area (Birds Directive)
83.55 km² overlap
Le Gardon et ses gorges
IUCN Not ReportedSpecial Areas of Conservation (Habitats Directive)
61.83 km² overlap
Gorges du Gardon
IUCN Not ReportedSpecial Protection Area (Birds Directive)
61.83 km² overlap
Camp des Garrigues
IUCN Not ReportedSpecial Protection Area (Birds Directive)
20.85 km² overlap
17 more protected areassorted by overlap area
Garrigues de Lussan
IUCN Not ReportedSpecial Protection Area (Birds Directive)
7.52 km² overlap
Costières nîmoises
IUCN Not ReportedSpecial Protection Area (Birds Directive)
7.25 km² overlap
Falaises d'Anduze
IUCN Not ReportedSpecial Areas of Conservation (Habitats Directive)
5.35 km² overlap
Gorges Du Gardon
IUCN IVRegional Nature Reserve
4.98 km² overlap
Gorges Du Gardon
IUCN IVBiotope Protection Order
3.39 km² overlap
Étang et mares de la Capelle
IUCN Not ReportedSpecial Areas of Conservation (Habitats Directive)
3.14 km² overlap
Vallée De L\'Avène
IUCN IVBiotope Protection Order
3.11 km² overlap
parignargues
IUCN IVLand acquired by a regional conservatory of natural areas
2.54 km² overlap
rnr gorges du gardon
IUCN IVLand acquired by a regional conservatory of natural areas
0.56 km² overlap
Le Rhône aval
IUCN Not ReportedSpecial Areas of Conservation (Habitats Directive)
0.23 km² overlap
Geotope Protection Order
0.17 km² overlap
Gisements à vertébrés de Champ-Garimond et de Fons
IUCN Not ReportedGeotope Protection Order
0.17 km² overlap
costieres de nimes
IUCN IVLand acquired by a regional conservatory of natural areas
0.14 km² overlap
Étang de Valliguières
IUCN Not ReportedSpecial Areas of Conservation (Habitats Directive)
0.07 km² overlap
etang de valliguieres
IUCN IVLand acquired by a regional conservatory of natural areas
0.05 km² overlap
Vallées du Tarn, du Tarnon et de la Mimente
IUCN Not ReportedSpecial Areas of Conservation (Habitats Directive)
0.02 km² overlap
Hautes vallées de la Cèze et du Luech
IUCN Not ReportedSpecial Areas of Conservation (Habitats Directive)
0.02 km² overlap
Computed live · GADM 4.1 × HydroBASINS lev08 × WDPA · cached after first hit.
Species present
8 902 distinct species · 719 508 observations
Source: GBIF Occurrence snapshot 2026-05-01.
Ecological tissue
Sample of 38 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'Alzon : 34 espèces + 4 bulles famille, 55 interactions GloBI documentées sur 5 types (connectance 7.8%, filtre Serrano α=0.2). Les 4 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°
12,4°C
Annual rain
751mm
Moisture idx (CMI)
-0,23
Runoff
537mm/an
PET
973mm
AET
629mm
Mean slope
8,8°
Water table
359cm
Forest
61%
Crops
20%
Urban
4%
Protected
39%
HydroATLAS BasinATLAS v10 (Linke et al. 2019) · HydroBASINS lev08 (Lehner & Grill 2013)