To simulate the propagation of floods in the Senegal River valley in order to lay out the flood risk maps, we used hydraulic methods calculating the flooded surface from the topography of the minor and major beds. To this end, the HECRAS model and GIS (ARCGIS and HEC-GeoRAS) were used on the Bakel-Matam reach. The work was done in steady state and allowed us to map the risk of flooding on this Bakel-Matam section in the Senegal River valley for different floods. to do this work, water levels and flows were used for the calibration and validation of the HEC-RAS model. The Nash criterion was used to optimize the HEC-RAS parameters. The flood extent obtained by this model was exported and visualized in ArcGIS. Thus, the flood mapping results obtained made it possible to detect a certain number of villages at risk of flooding for the hundred-year flow, wich shows that the Senegal River Valley is vulnerable to floods. Moreover, this was demonstrated by the average catastrophic flood which caused flooding that could impact approximately 24,071 people. The characteristics (height, speed and propagation time) for each flood were analyzed. The promising results obtained showed that the couple HECRAS and GIS is an effective tool for mapping floods and could be used as a tool to help planners in planning.