Analysis of the Silting Rate in the “Hachef” Dam Situated in Northern Morocco in the Context of Global Change

The Moroccan annual dam silting corresponds to a loss in storage capacity of the reservoirs of about 75 million m3 per year. Land use metamorphosis and the ongoing climate changes are likely to accelerate the process of soil degradation and erosion. In this delicate context, Morocco will have to provide appropriate responses in terms of adaptation and remediation strategies to the degradation of soil and water resources. The objectives of this paper are to characterize the Specific Degradation (SD) of the Tangier basin through the study of the silting of the watershed located upstream the Hachef dam and to analyze the silting rate of the Hachef dam according to the variability of precipitations and the dynamics of the vegetation convent. The adopted approach is based on the analysis of the bathymetric surveys of the Hachef Dam to characterize the SD and the analysis of the silting rate based on the characterization of the spatial and temporal variability of the two key factors of water erosion. The results of processing the bathymetric surveys over a 19-year analysis period (1995-2014) show an annual average total silting of about 11.46 Mm3 and a corresponding SD of about 36.7 t⋅ha−1⋅yr−1. This study shows the significant influence of the spatial and temporal variability of precipitation and vegetation cover on the silting dynamics of dams.