Abstract
The purpose of the study reported was to apply and verify a model of water balance of spatially distributed parameters in a meso-scale river catchment. The model was applied in the basin of Rega river, with the use of meteorological and hydrological measurement data from the years 1956–1995. In modelling, due account was taken of the land use changes having occurred during the 40-year period considered. The output from modelling was constituted by the raster maps of area evaporation, surface runoff and supply of the underground water resources. On the basis of these results the magnitude of outflow and the structure of water balance were calculated for three river gauge profiles. The deviations of the model-based calculated outflow values from the measured ones were maximally equal +10% for the entire 40-year period and +20% in one of the 5-year sub-periods.