Decadal Precipitation Variances and Reservoir Inflow in the Semi-Arid Upper Draa Basin (South-Eastern Morocco)

Water resources in the Upper Draa basin south of the High Atlas Mountains are of high importance for the persistence of human settlement in this region. To enlighten the hydro-climatologic situation, precipitation data from regional stations was analysed with respect to changes in annual precipitation sums and intensities. Then the inflow into the reservoir, its annual variability and its connection to precipitation events of different intensities was investigated. It was found that precipitation has a high variability that covers possible trends during the last decades. The study is concluded with an appraisal of the current and future hydrological regime of the Upper Draa basin in the regard of water availability. Climate change is predicted to decrease annual precipitation sums but to increase precipitation intensities which leads to a higher number of floods. Since it was shown that floods provide most of the water volume for the reservoir Mansour Eddahbi, more research of the regional interdependencies is needed.