A spatially distributed model for the simulation of snow accumulation and melt is presented. Watershed information on topography, vegetation and soils in digital terrain models (overlays) serve as the data base for watershed analysis, classification of snow in Landsat imagery and automatic generation of parameter decks for operating distributed simulation models of snowcover dynamics and streamflow generation. Snow processes are simulated within variable size grid-cell elements. The hydrograph resulting from spring snowmelt is simulated by a lateral flow model of streamflow generation driven by simulated snowmelt and rain inputs. Options are avilable for simulating the effects of forest management alternatives on selected areas. Snow course measurements and classified Landsat imagery are used for updating simulated parameters.