Abstract

The natural hydrologic conditions are changed after the construction of Three Georges Reservoir (TGR) in the Yangtze River, which will cause the sediment erosion and the change of the channel morphology downstream from the dam. Considering the unsteady characteristics of the river flow and the morphology of multiply branching channel in the middle Yangtze River, the unsteady flow and sediment model of river networks is presented in this paper. Based on the analysis of the sediment transportation process after the dam construction, the channel degradation of this reach after the construction of TGR was forecasted by using the foregoing model. Comparing with the existed researches and the field data, it is shown that the prediction of the channel degradation in the middle Yangtze River after the construction of the TGR by using the model is less than the existed prediction, and more similar with the field data. These results can be referred to the river channel training, flood control, and navigation management in the middle reach of Yangtze River after the construction of TGR.

Keywords: degradation; the Three Gorges Reservoir; prediction; numerical model