A semi-distributed rainfall-runoff model based on a geomorphologic approach

DRiFt (Discharge River Forecast), a semi-distributed event model based on a geomorphologic approach, is presented. This model is focused on the effici ent description of the drainage system in its essential parts: hillslopes a nd channel networks are addressed with two kinematic scales, which determin e the base of the geomorphologic response of the basin. The geomorphologic module is coupled with a simple distributed representation of soil infiltra tion properties, while the rainfall event is schematized with its variabili ty in time and space. The runoff volume is routed with a time variant TUH ( T-hour Unit Hydrograph) technique, which takes into account the runoff prod uction variability. Parameters calibration and validation have been carried out using different intense rainfall events in different size basins. This robust and parsimonious model is able to predict consistently the main fea tures of the hydrograph; the observed parameter invariance allows the relia ble utilization for flood forecasting, especially in regions where many sma ll non-gauged basins are present. (C) 2000 Elsevier Science Ltd. All rights reserved.