Modeling runoff generation in the Geer river basin with improved model parameterizations to the REW approach

A rainfall-runoff model has been developed for the Geer river catchment based on the Representative Elementary Watershed (REW) approach. The approach takes into account five dominant hydrological processes. The entire river catchment is descritized into a finite number of sub-catchments, or REWs. To describe these processes, five flow zones within each REW are distinguished. Within each zone, averaged values for state variables and model parameters are used. In this research, some new model parameterizations are introduced. A consistency analysis has been carried out with respect to the effects of the subsurface parameterization on runoff generation processes for the purpose of evaluating model behavior. In addition, a new approach for representing the relation between topography and the variable source area for the saturation overland flow within a REW is proposed. Results show that the improved model parameterization produces better simulations of river discharge and that the REW approach is an appropriate tool for investigating rainfall runoff relations.