May land use change reduce the water deficiency problem caused by reduced brown coal mining in the state of Brandenburg?

Surface mining alters the water regime not only locally, but also regionall y. The reduced brown coal mining in the southeast of the state Brandenburg (Germany) leads to decreasing river discharge and consequently to a shortag e in the water supply. Land use change is one possible option to counteract this development. In this simulation study, we explored the impact of temp orary and permanent set-aside of arable land on Brandenburg's regional wate r balance. Temporary and permanent set-aside were considered as major measu res towards deintensification of agriculture. Simulations were performed us ing the regional ecohydrological model SWIM, which integrates hydrological processes, vegetation growth, erosion and nutrient dynamics. The model was used to simulate the consequences of different land use change scenarios on main components of the regional water balance. Changes in the use of arabl e land altered clearly its water balance. The impact of these changes on th e regional water balance for Brandenburg did not exceed +/-10% for its sing le components. Opposite tendencies were established in the simulations by c ontrasting effects of temporary and permanent set-aside of arable cropland. While temporary set-aside increased runoff from the whole area up to 6.7% due to lower evapotranspiration and higher soil moisture in arable land, th e conversion of agricultural land within river corridors to meadows had an opposite effect on regional runoff (6.9% decrease) due to higher water rete ntion coefficients and higher evapotranspiration losses. Therefore, only te mporary set-aside may compensate to some extent for the anticipated decreas e in river discharge. (C) 2000 Elsevier Science B.V. All rights reserved.