In this study, the impact of climate change scenarios on the hydrological
regimes of five different regions in Germany is investigated. These regions
(Northwest Germany, Northeast Germany and East German basins, upper and
lower Rhine, pre-Alps) differ with respect to present climate and projected
climate change. The physically based SVAT-model SIMULAT is applied to
theoretical soil columns based on combinations of land use, soil texture and
groundwater depth to quantify climate change effects on the hydrological
regime. Observed climate, measured at climate stations of the German Weather
Service (1991–2007), is used for comparison with climate projections
(2071–2100) generated by the regional scale climate model WETTREG.
While all climate scenarios implicate an increase in precipitation in
winter, a decrease in precipitation in summer and an increase in
temperature, the simulated impacts on the hydrological regime are regionally
different. In the Rhine region and in Northwest Germany, an increase in the
annual runoff and groundwater recharge is simulated despite the increase in
temperature and potential evapotranspiration. In the Eastern part of Germany
and the pre-Alps, annual runoff and groundwater recharge will decrease. Due
to dry conditions in summer, the soil moisture deficit will increase (in
Northeast Germany and the East German basins in particular) or remain
constant (Rhine region). In all regions the seasonal variability in runoff
and soil moisture status will increase. Despite regional warming actual
evapotranspiration will decrease in most regions except in areas with
shallow groundwater tables and the lower Rhine. Although the study is
limited by the fact that only one climate model was used to drive one
hydrologic model, the study shows that the hydrological regime will be
affected by climate change. The direction of the expected changes seems to
be obvious as well as the necessity of the adaptation of future water
management strategies. |