– 0 – – – CLASSIFICATION OF SMALL ALPINE CATCHMENTS A TOOL TO SUPPORT THE CHOICE OF RAINFALL-RUNOFF-MODELS

Thanks to increasing computer capacities a large number of rainfall-runoff-models have been developed during recent decades in order to simulate discharge and to forecast flood events. Though most of these models yield good results in the catchments, the data of which were used in the model development process, their transfer to other catchments raises difficulties. This is due to site-specific simplifications in the model structure because of missing knowledge of the hydrological processes in detail or missing input data. At the current state of knowledge and data availability it is not possible to develop an entirely physically based model applicable to a wide range of catchments (Beven, 2002). As a consequence great effort has to be made to find out which one of the existing rainfall-runoff-models ‘performs well, where and for what purpose ’ (Beven 2006). The development of a catchment classification system may contribute to improve this situation. As catchment characteristics vary strongly within space and time a catchment classification can help to identify affinities regarding hydrologically relevant aspects. Catchments belonging to the same class are meant to show similar reactions to comparable current system conditions and precipitation events. Catchment classes can then be assigned t