Modelling of water balance under changed climate conditions has been carried out by T. G. Masaryk Water Research Institute in Prague for basins in the Czech Republic since 1990 . The studies presently use climate change scenarios derived from simulations by regional climate models. Climate change scenarios are reflected in meteorological time-series for given catchment and subsequently used for simulation of water cycle components by using Bilan water balance model. The Bilan model can be used

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... or assessing water balance components of a catchment in monthly or daily step. The model simulates water budget at three vertical levels. Three water balance algorithms that are applied were developed for winter conditions, snow melting and summer conditions. Excess water forms direct runoff or infiltrates to deeper zones, where it is divided into interflow and groundwater recharge. Results of Bilan model simulations for input meteorological series not affected and affected by climate change scenarios give information for assessing the climate change impacts on output series of the model. The results of the studies generally show that annual runoff could largely decrease. The increased winter temperature could cause an increase in winter outflows and a decrease in snow storage, and consequently, spring and summer outflows will decrease significantly, even to their current minimum values. The groundwater storage and base flow could also be highly reduced. The described method has been used in a number of research projects and operational applications. Its typical application is aimed at assessing possible impacts of climate change on surface water resources, whose availability can subsequently be analysed by water management studies of the individual basins. The Bilan model, particularly in combination with Modflow model, can also suitably be used for simulation and assessments of groundwater resources.