Land use dynamics in the context of variations in hydrological regimes in the upper Senegal River basin

Abstract

The objective of this study is to analisis the climatic vulnerability of water resources in the Senegal iver and Gambia basins. The study concerns the analysis of rainfall data, flow rates of Modis-Terra satellite images. Time series of study data are variable. The purpose of this study is to analysis climate vulnerability on water resources in the Senegal River and Gambia basins. It is based on the exploitation, on the one hand, of the chronicles of annual rainfall amounts and annual flows of the tributaries of the Bafing at the Bafing Makana station, from Senegal at the Bakel station, from Bakoye to Oulia and from Faleme to Kidira over the period 1955-2014 and, on the other hand, of Modis-Terra satellite images from 2007 and Modis-Terra from 2014. The calculation of rainfall and hydrometric indices and the application of statistical tests made it possible to analyze hydro-pluviometric variability in the Senegal River and Gambia basins. This variability is characterized by comparable fluctuations in precipitation and runoff. The break identified on the rainfall and hydrometric series from the late 1960s onwards resulted in a rainfall deficit of 12% to 18% and a flow deficit of 66% after the break. The analysis of land use maps based on satellite imagery has made it possible to identify the dynamics of land use. This dynamic is characterized by the regression of natural plant formations in favor of anthropogenic ones. Fields and fallows experienced the greatest expansion with a rate of 7.8%, bare soils (8.8%). However, the forest and savannah experienced a decline of (-10.35%) and water bodies (-0.2%) following the 2007-2014 period. The degradation of the vegetation cover is undoubtedly one of the factors contributing to the persistence of the relatively high level of hydrometric deficit in the upper basin.