Author(s): Dongdong Jia; Xuejun Shao; Yang Shen; Haifeng Jiang
Linked Author(s):
Keywords: Middle Yangtze River; Changes of flow and sediment regime; Planform evolution; Numerical simulation
Abstract: The operation of the Three Gorges Reservoir (TGR) will significantly change the hydrological conditions in the middle Yangtze River (MYR), particularly the sediment concentration. The scientific understanding of how decrease of sediment influences the processes of bank erosion and channel adjustments is complex and limited. In the present paper, the effects of flow and sediment regime changes due to the TGR operation on channel adjustments in the Shishou reach of the MYR were investigated by a 3-D morphodynamic model, in which turbulence flow, sediment transport and bank erosion are modeling. This model can not only calculate the vertical bed deformation, but also can simulate the lateral migration in alluvial rivers. Observed sediment load on the Shishou reach is decreased by 75% after the early filling of the TGR. The magnitude of bed degradation with less sediment load due to the TGR operation is increased compared with the pre-dam situation. Overall, the plan form evolution trends in the Shishou reach after the TGR operation are similar to that without the TGR operation. The magnitude of lateral migration has been increased in some part of the reach, where the morphological response of the TGR operation exhibits more lateral migration rather than vertical degradation. Decrease of sediment load and weak bank anti-scour ability as well as the significant helical flow can be responsible for accelerated bank erosion in the study reach.
Year: 2013