The parameterization of physically-based, distributed hydrological watershed models requires areal analysis of the water cycle components. Besides topographical, pedological and geological factors the actual land use is an important input parameter for the physical and chemical modelling of the watershed hydrology and plays a signicant role in the GIS-based delineation of the modelling entities that are used to preserve the spatial heterogeneity of catchments within physically-based, distributed hydrological models.