Mathematical Model of the Hydrodynamics and Sediment Transport in the Sanba Village Bend of the Shaying River in China

To study the impact of waterway regulation engineering on river regime adjustment and river evolution, a two-dimensional mathematical model of the hydrodynamics and sediment transport in a typical bend reach of the Shaying River (the largest tributary of the Huai River in China), namely the Sanba Village bend reach, was constructed. After model calibration and validation, the model was used to simulate and analyze the impact of the bend beach cutting project on the flow conditions of the bend reach and to reveal the changes in the river regime caused by the project. We selected a representative 10-year water and sediment series to simulate the changes in the hydraulic and sediment factors caused by the Sanba Village bend beach cutting project, and we analyzed the beach stability of the newly opened channel, the riverbed undercutting speed, and the sedimentation rate of the old river retained on the left side (before the beach cutting project). It was found that after cutting the bend beach, the flow velocity in the main channel of the river increased, while the flow velocity in the beach decreased. The erosion thickness of the main channel of the Sanba Village bend reach under the condition of cutting the beach was smaller to that under the condition of not cutting the beach, whereas the sedimentation on the convex bank was weakened. Based on the results of the water and sediment changes and river evolution, the erosion and sedimentation characteristics of the Sanba Village bend reach after channel regulation and the future development trends were estimated.