Future climate and changes in flow patterns in Czech headwater catchments

The aim of this study was to estimate the impacts of anticipated global climate change on runoff and evapotranspiration in small-forested catchments. The investigated Lysina and Pluhuv Bor catchments are situated in the Slavkov Forest in western Czech Republic. To forecast hydrological patterns for the period 2071-2100, outputs from 2 general circulation models, HadAM3H and ECHAM4/OPYC3, were downscaled using 3 regional climate models (RCM; RCAO, CHRM, HIRHAM) under the A2 and B2 emission scenarios (Intergovernmental Panel on Climate Change Special Report on Emissions Scenarios). Corrected RCM daily outputs were used in combination with the hydrological model Brook90. Annual runoff is projected to decline by 10 to 30%, and impacts on the distribution of monthly flow are projected to be significant, with summer-autumn decreases of 30 to 95%, and winter increases of up to similar to 40% compared to mean discharge for the period 1967-1990. Mean daily flows are estimated to decrease by similar to 70% from August to November. These changes would have serious ecological consequences since streams could regularly dry up for short periods.