Regionalisation concept for hydrological modelling on different scales using a physically based model:: Results and evaluation

A regionalisation concept for hydrological modelling on different scales using a physically based simulation model is presented. It enables us to calculate regional water balances by simulating a limited number of representative ecotopes (=hydro-pedotopes) instead of all units using a physically based model system (soil-vegetation-atmosphere-transfer-scheme). Using a cluster analysis the hydrological quantities (e.g. monthly values of actual evapotranspiration, groundwater recharge, surface runoff and interflow) of all ecotopes were analysed and groups of similar behaviour defined. For each of these clusters one representative ecotope is chosen. Results of an application of this concept are presented. The water fluxes of a 1000 km(2) catchment in Germany were calculated and simulated runoff compared with measured. Simulating selected representative instead of all ecotopes reduces the number of necessary simulation runs by up to 95%. The results suggest that the quality of the simulation is not effected by using representative instead of all ecotopes. Because the data were not aggregated the spatial pattern of properties and fluxes is preserved. In order to evaluate the moder results, the uncertainties concerning the data base (e.g. soil map, weather data) and the assumptions included in the regionalisation concept are investigated. Because in this concept no model calibration is performed, the applicability is only limited by the data availability (spatial and temporal resolution). The model shows a reliable hydrological behaviour and is a suitable tool for landscape management. (C) 1999 Elsevier Science Ltd. All rights reserved.