One-dimensional modelling of suspended sediment dynamics in dam reservoirs

International audience; Continuous sedimentation of fine sediments in dam reservoirs triggers considerable economic and ecological impacts worldwide. The definition of appropriate reservoir management procedures requires accurate tools for predicting the sediment dynamics both in the reservoir and downstream reaches. In this article, a one-dimensional numerical model aiming to reproduce suspended sediment dynamics is presented. To take into account water intake locations and vertical distribution of suspended sediments in areas of larger water depths close to dams, an additional module is developed. The model is applied to a reach of the French Upper Rhône River, including two reservoirs. The calibrated model provides accurate flux estimates and reproduces erosion and deposition patterns observed in the reservoir for several scenarios. The additional module allows to improve the estimation of the sand load released by low-level outlets. Eventually, the model could be used either to provide insights on the outcome of past flushing operations or as a predictive tool to prepare future operations.