Changes in Water Resources Systems: Methodologies to Maintain Water Security and Ensure Integrated Management (Proceedings of Symposium HS3006 at IUGG2007, Perugia, July 2007). IAHS Publ. 315, 2007, 310-319.

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A water balance approach to indicate effects of man-made enhanced greenhouse warming on groundwater recharge in the Kalahari

Heike Wanke¹, Ulrike Beyer², Armin Dünkeloh¹ & Peter Udluft¹

1 LFB Hydrogeology, Institute for Geology, University Würzburg, Germany

a.h.wanke@web.de

2 Department of Geography, University Augsburg, Germany

Abstract In this study the distributed, process-oriented, physically-based water balance model MODBIL is set up for two Kalahari sub-catchments in northeastern Namibia and northwestern Botswana to show possible impacts of climatic 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.

Key words greenhouse warming; groundwater recharge; Kalahari; statistical downscaling; water balance model

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