Analysis of flow in the Senegal River basin from 1960 to 2008
Since the commissioning of Diama and Manantali dams, the hydrological regime of the Senegal river depends on the cumulative impact of climate variability and dams. Nowadays, in the valley of the river there is an increase in flooding. The aim of this research was to analyze the evolution of the hydrological regime of the Senegal River in order to determine the effect of both climate variability and the dams on stream flows. A statistical approach combining several complementary methods (standard scores indices, tests for statistical ruptures and a segmentation series procedure) was used. Our analysis revealed that in the Senegal River Basin, a climatic break in the 1970s resulted in a decrease in the mean annual discharge and also in the annual maximum and minimum water levels. However, a significant recovery of the average annual flow is observed from around 1994, demonstrating the occurrence of a new climatic period, wetter than the 1970s and 1980s, across the Senegal River basin. In addition, in the river valley, the yearly mean of the flow is supported, since the late 1980s and early 1990s, by the cumulative effect of the dams (by their impact on land use) and climate variability. Furthermore, dams have led to an increase of the maximum annual flood levels at the Bakel station since 1994, and to a considerable support of low flows across the entire Senegal River Valley.