An integrated approach to the efficient management of scarce freshwater resources in tropical West Africa: the IMPETUS project

Since the year 2000, the German multi-disciplinary research project (IMPETUS, “An Integrated Approach to the Efficient Management of Scarce Water Resources in West Africa”) has devoted significant efforts to a better diagnosis, understanding, and modelling of the key processes driving changes in the atmospheric and terrestrial branches of the hydrological cycle in a 46,500 km2 large watershed located in the semi-humid monsoon climate of West Africa in the Republic of Benin. Water-related problems in the upper Ouémé river catchment (annual precipitation ca. 1100 mm) presently arise from the poor water quality rather than the scarcity of water. However, a strong population increase augmented by migration, future increased demands from households, agriculture and industry, the rapid degradation of soils and vegetation and their feedback on the local rainfall patterns, and the anticipated greenhouse gas related climate change will dramatically increase the pressure on the resource freshwater. This anticipated development requires integrated management strategies and the provision of decision support systems for local stakeholders.

IMPETUS has set up three regional development scenarios until 2025 using expert knowledge and models from various disciplines. As an external climatic driving factor, the IPCC SRES scenario B2 has been used to force a nested atmospheric model hierarchy as a dynamical downscaling tool. In the present contribution the methodology of achieving such complex multidisciplinary scenarios will be presented and three applications in the field of river hydrology, the influence of modelled land-use changes on rainfall, and water-related health impacts (e. g. malaria and salmonella diseases) will be presented.