Author(s): Peng Zhang, Shengfa Yang, Jiang Hu, Mi Tian, Shuaishuai Zhang, Sichen Tong, Xuelian Liu, Ying Shen, Tao Wang
Linked Author(s): Peng Zhang
Keywords: Non-uniform flows, Three Gorges Reservoir (TGR), Saint-Venant equations, friction velocity, mean velocity profile
Abstract: Non-uniform flows are often encountered in Three Gorges Reservoir (TGR). When the storage level is at flood control level of 145m, the permanent backwater region is gradually decelerating flow, with the length of 524 km. Field measurements are conducted in the permanent backwater region in Three Gorges Reservoir. The flow instantaneous velocities are measured by using ADCP. Based on the theoretical and experimental analysis methods, this study investigates friction velocity, mean velocity distribution in non-uniform flows in permanent backwater region. Equations of friction velocity are derived by one dimensional open channel Saint - Venant equations. The theoretical results show that influence by the variation of water surface in non-uniform flows has resulted in relationship between friction velocity and the flow depth gradient. The theoretical results are in good agreement with field measurements data. The mean velocity profile in non-uniform flows flat with the increasing of H/H0 (where H0, as the uniform flow depth, which meets the Chezy Manning formula uniform flow, in the case of a certain discharge per unit width, roughness and slope of river bed condition). The relationship between slopes of log-law velocity profiles and H/H0 show a power function
Year: 2017