Influence of Climate Change on River Discharge in Austria

The effect of climate change on the river discharge characteristics in four catchment basins within Austria is investigated using a hydrological model. Input for the model are daily climate data generated from three regional climate models (RCMs) over the time period 1951-2100 using the A1B emission scenario. Due to the complex terrain of the basins, the climate data has been downscaled to a resolution of 1 km x 1km. The hydrological model includes processes such as meltwater from snow and glaciers; surface, subsurface, and groundwater flows; and evapotranspiration. The modelling results show that, although only one RCM exhibits a significant reduction in the mean annual discharge towards the end of the 21st century, all RCMs exhibit significant changes in the seasonal distribution of the discharge. In particular, for basins whose discharge is dependent on water stored as snow, there will be a shift in the time of maximum river discharge to earlier in the year as the snow and ice melt earlier. During the winter months the discharge is forecasted to be higher than at present, which would lead to the number of days of low discharge being reduced. However, the earlier snow melt means that the available water for the summer months will be reduced, leading to lower discharges than present, and thus an increase in the number of low discharge days.