The purpose of this report is to provide a brief general description of the topography, drainage, rainfall and evapotranspiration of the areas concerned. Where available, this is supplemented by additional hydrological information. The report is meant to form a basis for future more detailed studies on the subject.br It should be pointed out that lack of data for large parts of the drainage basins (particularly those situated in Ethiopia) has meant that the information contained in this report had to be kept rather general.