Abstract: The operation of Three Gorges Reservoir at 175m impounded water level will have a significant impact on the flow characteristics in backwater area. Analysis in this regard will provide theoretical support for the waterway regulation, navigation planning, and study on water and sediment regularities. According to the observed data from hydrology bureau in the upstream of Yangtze river, we employed Aquaveo.SMS to establish a two-dimensional plane flow model, and simulated the hydrodynamic conditions in the presence of and in the absence of backwater in different periods of year to analyse the influence of backwater on hydrodynamic conditions (flow field, horizontal distribution of flow velocity, and hydrodynamic axis). Zhuerqi reach in the backwater area is selected as a typical example for the research. The numerical simulation method could be taken as reference for similar study.

Key words: Zhuerqi reach, 175 m impoundment, flow characteristics, 2D mathematical model of flow, hydrodynamic conditions