Vieux Boukhaly Traore^1,, Mamadou Bop¹, Moustapha Faye², Giovani Malomar², El Hadj Oumar Gueye³, Hyacinthe Sambou^{4, 5}, Abdoulaye Ndiaye Dione³, Sidy Fall⁶, Amadou Tahirou Diaw⁵, Joseph Sarr², Aboubaker Chedikh Beye^{1, 7}

In West Africa, there is serious asymmetry on food safety between consumers and food producers. This made that the management system of food safety in many developing countries became a top priority for authorities and decision makers. In Senegal, the government has selected the flood plain of Kayanga River to develop irrigated agriculture through rice cultivation to promote the food safety. For this, two dams (Niandouba and Confluent) have been built to reinforce water availability .The management of this hydraulic system required the better knowledge of its water resources through the dynamic of the flow. In this paper, we used Hec-ras model to compute the flow characteristics to analyze the hydraulic behavior of this system. The river reach selected, is located between the Niandouba dam and Kounkane threshold. From the DEM of this area, we have divided the river reach into 78 cross sections perpendicular to flow direction and numbered from 1 to 78. Arcgis software is used to extract the bathymetry for each cross section and the distance between two adjacent cross sections. This step allows creating the river geometry with Hec-ras. Four stream flows have successively fixed at Niandouba dam outlet as upstream boundaries. For each stream flow, Hec-ras calculate flow characteristics including: water surface profiles, energy grade line, water surface elevation, flow velocity, flow area, total surface area, volume, wetted perimeter, Froude number, top width, specif force, shear total, power total ,friction loss, head loss, conveyance total, and slope. The high, low and constant flow characteristics areas have been located. The large and narrow section sectors have also been identified allowing estimating floodplain. Certain of these flow characteristics such as the volume, total surface area…decrease from upstream to downstream. Flow velocities are substantially higher in the main channel than in the floodway. This study provides an opportunity for stakeholders to identify important elements of irrigated agriculture for investment plans in this area.

hec-ras, hydraulic analysis, kayanga river basin, hydraulic behavior, water resources knowledge, food safety