Distributed hydrological modeling and sensitivity analysis in Torysa watershed, Slovakia

The spatially distributed hydrologic model WetSpa is applied to the Torysa river basin (1,297 km(2)) located in Slovakia. Daily hydrometeorological data from 1991 to 2000 are used as input to the model. The spatial characteristic of the basin are described by three base maps, i.e. DEM, landuse and soil type, in GIS form using 100 m cell size. Results of the simulations show a good agreement between calculated and measured hydrographs at the outlet of the basin. The model predicts the daily discharge values with a good accuracy, i.e. about 73% according to the Nash-Sutcliff criterion. Sensitivity analysis of the model parameters is performed using a model-independent parameter estimator, PEST. It is found that the correction factor for calculating the actual evapotranspiration from potential evaporation has the highest relative sensitivity. Parameter K-gm which controls the amount of evapotranspiration from the groundwater has the least relative sensitivity.