Role of vegetation in the variability of water regimes in the Sumava Mts forest

Deviations between observed and simulated discharge in the basins along the borders of the Czech Republic with Austria and Germany provide outputs which enable to follow changes in runoff. The three basins range in area from 100 to 200 km 2 and the experimental basin Liz with an area of 0.99 km(2). The selected experimental catchments are situated in or close to the National Park of the Sumava Mts. This region is described also in TESAR et al. (2006). Results indicate that changes in runoff appear to be related to damages in forest cover caused by wind disasters and insects damages. Daily time series used for simulations are approximately 40 years long and 20 years in the experimental basin. Two different models of the rainfall - runoff process have been used for simulations and the outputs provide comparable results. The models are the conceptual model Sacramento (BURNASH, 1995) and the model BROOK'90 (FEDERER, 1993). The second model distinguishes the details concerning evapotranspiration, including transpiration, rain and snow interception and snow and soil evaporation. The indicated runoff changes seem to be rather complex. After deforestation the volume of runoff generally increases and peak flows of floods are higher, but low flow in rainless periods show complicated courses.