Abstract:The rise and decline of braided reach and the fluvial process of continent and shoal are closely related to the characteristics of hydraulic and sediment transport. The paper focuses on the Shashi reach

a typical multi branched meandering reach in the middle Yangtze River. Firstly

based on a large amount of field data

the evolution feature of this reach is analyzed in natural condition. Then

according to the effect of Three Gorge Project(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 is practical and helpful in the research on other multi-branched meandering reach in the middle Yangtze River after Three Gorges Reservoir impoundment.