Calibration of HEC-RAS Model for One Dimensional Steady Flow Analysis—A Case of Senegal River Estuary Downstream Diama Dam

The Sahelian regions have experienced a drought that\r\nhas made them vulnerable to hydro-climatic conditions. Strategies have been\r\ndeveloped to reduce this vulnerability. The\r\ngovernments of Senegal, Mauritania, Mali and Guinea have created the\r\nOrganization for the development of the Senegal River (OMVS in french) with the\r\naim of realizing large hydraulic installations. This resulted in the\r\nconstruction of the Diama and Manantali dams in the Senegal River Basin. The\r\nfirst aims to stop the saline intrusion, the second to regulate the flow of the\r\nriver, to allow the irrigation of agricultural perimeters, and to produce\r\nelectrical energy. The impoundment of the Diama dam has modified the hydraulic\r\nbehavior of the estuary. The purpose of this study is to carry out the hydraulic modeling of the estuary of Senegal\r\nriver downstream of the Diama Dam in transient mode by the HEC-RAS software.\r\nTwo geometric models were constructed on the basis of a digital terrain\r\nmodel (DTM) using the Arc-GIS and HEC GeoRAS soft wares after processing the\r\ncollected topographic data. The first geometric model, of which the areas of\r\nSenegal river downstream Diama Dam have been represented by cross-section, is\r\none-dimensional. The second one is also one\r\ndimensional; in this model, the area of the Senegal River estuary\r\ndownstream Diama Dam is introduced as water storage zones. The components of\r\nthese models are the stream sections, lateral links, and storage areas. The\r\nflood hydrograph downstream Diama Dam is introduced as conditions at the\r\nupstream limits of the models while the tidal is introduced as a downstream\r\ncondition. After the stability and calibration, the results given by HEC-RAS simulations\r\nare the variations of the water levels, the temporal variations of the flow\r\nrates for each section, the maximum flow velocities and the propagation times\r\nof the flood waves. The analysis and comparisons of these results strongly\r\nsuggest using HEC-RAS issues as a decision-making tool helping to manage floods\r\nduring times of crisis.