English Abstract During the past decades human interference in regional
hydrologic systems had intensified. These systems act as an integrating
medium. They link climate, human activities and ecological processes
through groundwater and surface water interactions. In this study we have
examined the potential impacts of climate change on the streams Beerze and
Reusel in the Netherlands, and also the possible interactions with other
influences like agricultural drainage. For examining the potential impacts
of climate change we have followed a scheme involving predictions for: -
indirect effects of climate change, that are transferred to ecological
subsystems through the regional hydrologic system. - direct effects of
climate change, through the direct influence of temperature on the
germination, flowering and fruiting of plant species. The results indicate
for the study region a heigh sensitivity of the peak discharges for the
precipitation: an increase of 17% in the winter precipitation caused a more
than 50% increase of the peak discharges. The upward seepage of groundwater
to the rootzone of natural vegetation is especially sensitive for the
evapotranspiration, and hardly not for the precipitation. Under all
scenarios the climate change had a significantly negative effect on the
stream community of the aquatic ecosystem. Compared with the impact of
other antropogenic influences like agricultural drainage, the effecs of
climate change on the area of wet and moist reverine grasslands are
moderate, and mostly they are positive.