Africa is not only suffering from water shortage but also from data shortage. The continent cannot fall back on a cross-country hydro-metcorological measuring net. Development cooperation organizations as planners often have the problem that no, or insufficient, hydro-meteorological data is available, even though these are of great importance for Sustainable water resources management. Usable water deposits are often not recorded in quantity, quality or in spatial and temporal distribution. The negative effects of insufficient data can only be avoided on a long-term basis. One has to know where, when and how much precipitation, evaporation, runoff and groundwater recharge can be expected. This is the basis for sustainable planning in the field of water resources management, agriculture, hydropower generation, erosion control, etc. The answer is the "setting up of a cross-national hydrometeorological measuring net for creating the preconditions of sustainable water resources management".