drainage basin An extent or area of land where surface water from rain and melting snow or ice converges to a single point at lower elevation, usually the exit of the basin, where the waters join another waterbody. Basin CATCHMENT Catchment ENVO ENVO:00000291 EcoLexicon:basin EcoLexicon:drainage_basin FTT:220 FTT:440 Geonames:L.BSND LTER:58 SWEETRealm:DrainageBasin TGN:21455 Watershed Wikipedia:Drainage_basin catchment drainage basin watershed depression