Using a conceptual rainfall-runoff model on different scales by comparing a headwater with larger basins

The conceptual rainfall-runoff model HBV was applied to four basins of diff erent sizes (257, 39.8, 15.2 and 0.093 km(2)) under very similar physiograp hic and climatic conditions. For some model parameters it was possible to r elate parameter values and parameter sensitivity to basin scale or physiogr aphic basin characteristics. Other parameters called the physical basis of the model into question. A regional parameter set valid for all basins coul d not be found because basin scale is not negligible. Drawing conclusions o n model parameter values from basin characteristics has been shown to requi re great caution.