Abstract

A lot of multi-branched meandering reaches exist in the middle Yangtze River. The fluvial change in these kind reach due to the impoundment and flow regulation of the Three Gorges Project (TGP) will have effect on the flood control, navigation and ecological environment and has draw wide concerns. The paper focuses on the Shashi reach, a typical multi-branched meandering reach in the middle Yangtze River. Firstly, according to the based on a large amount of field data, the evolution feature of this reach is analyzed in nature condition. Then, according to the effect of TGP on flow and sediment process, the trend of geomorphology change is predicted. Finally, based on the analysis above and the change character of flow & sediment, a depth-averaged 2-D flow and sediment numerical model is developed and applied to predict the further details of possible adjustments due to flow and sediment regulation after the TGP impoundment for 20 years. The results show that the fluvial process in the reach is closely related to the characteristics of flow and sediment transportation. The numerical model can simulate the characteristics of flow &sediment transportation and the rule of bars movement well. The prediction result is reasonable. The information provided in the paper can practical and helpful in the research on other multi-branched meandering reach in the middle Yangtze River after Three Gorges Reservoir impoundment.

Keywords: Three Gorge project, multi-branched meandering reach, fluvial process, 2-D mathematical model, numerical simulation