A Water Balance Approach to Indlcate Effects of Man-made Enhanced Greenliouse Warming on Groundwater Recharge in the Kalahari

In this study the distributed, processoriented, physically-based water balance model MOOBIL is set up for two Kalahari sub-catchments in northeastern Namibia and northwester Botswana to show possible impacts ofclimatic change on groundwater recharge. The results of the 22-year-long calibration period are verified with the chloride mass balance and hydrographs, and are in the next step compared with results of a prediction simulation. For the prediction water balance model, precipitation time series under conditions of enhanced greenhouse warming have been produced based on statistical downscaling procedures of large-scale circulation models and regional climate. Results reveal that summer rainfall in northeastern Namibia will be temporarily more pronounced with significantly increased precipitation during January and February, but less precipitation in March. With this approach an increase in mean groundwater recharge and interflow is predicted for the two catchments.