Simulating the variable-source-area concept of streamflow generation with the watershed model TOPMODEL

This report describes TOPMODEL, which is a physically based watershed model that simulates the variable-source-area concept of streamflow generation. The report describes the theoretical background, model equations, methods to determine parameter values, Fortran computer code, and an example interactive simulation. Using TOPMODEL requires specification of soils and topographic parameters, watershed latitude, and time series of precipitation and air temperature. Model predictions include, in addition to streamflow, estimates of overland and subsurface flow, and an estimate of the spatial pattern of the depth to the water table in the watershed.