Belgeo (Dec 2015)
Impacts des changements de climat et des aménagements sur les ressources en eau du fleuve Sénégal : caractérisation et évolution des régimes hydrologiques de sous-bassins versants naturels et aménagés
Abstract
For several decades, numerous countries have given high priority to the preservation, the use and the sustainable development of water resources in order to provide responses to the deficit of hydrological flow and in response to increasing population demands. Facing these various evolutions, Senegal River basin is going to experience a set of major arrangements on some of its sections (Manantali on Bafing river, Diama in the valley). The present work has to be analyzed through this perspective. Its main objective is the evaluation of the water resources of the Senegal River in a context of changes in climatic conditions and basins managements. This work is based on an analysis of the spatio-temporal variations of the flow while proceeding to a comparison of Senegal River basin, through its various regimes. To evaluate the impact of the drought and its effects on the flow of the river within various sub-basins, monthly and annual hydrometric series covering the period 1960-2014 have been used. This approach includes: (1) updating of incomplete data, (2) calculation of monthly (CMD), seasonal and annual coefficients of flows and their subdivision into two series with different period (1960 to 2014 and 1970 to 2014), (3) trends detection within both series by the application of two tests (Pettitt and Mann-Kendall). This application on both series indicates a double “breakdown” (often significant with a threshold of 1 %). The first one, between 1967 and 1976, is noted in the series 1960-2014 and the second, between 1990 and 1994, in the series 1970-2014. By comparison between stations, we have noticed that the trends or the breakdown in river basins with natural flow (Falémé, Bakoye) are due to climate change, while those in basins with man-made flow (Bakel and water releases from the dam), to be entrained by the subsequent managements within the basins.
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