水电站日调节和泄洪引起的非恒定流改变了下游河道的天然水沙过程,将影响下游河道的防洪、航道、港口及船舶航行安全,需研究坝下非恒定流的传播规律、关注航道内比降与流速的变化以及航槽内的输沙特性,实现水电与航运协调发展.结合向家坝水电站下游滩段的物理模型试验与坝下一维数模计算的成果,开展了电站下泄非恒定流对下游水位、流量、比降、流速及输沙的影响研究.结果表明:日调节引起的坝下水位、流量变化沿程坦化,水位与流量变幅沿程减小;随着电站泄水波的行进,峰前瞬时比降和水流速度相应增大,退水时沿程水面比降与流速随谷减小,随后恢复原有的比降(流速)与流量关系;泄水波峰前最大比降随流量变率的增大而增加,与流量的变幅无关;非恒定流输沙率大于恒定流的输沙率.%The water and sediment process downstream of the dam are changed by unsteady flow of plant daily regulation and discharge process. The downstream flood control, navigation, ports, and ship navigation safety would be affected, therefore it is necessary to study the propagation rule of unsteady flow, the velocity and water slope variation in the channel, the characteristic of sediment transport in downstream channel for the coordination between the hydropower construction and the development of shipping. By using 1-D numerical model and physical model, researches of water level, discharge, water slope, velocity and sediment transport downstream of dam influenced by unsteady flow are carried out. The results show that the streamwise water level and the downstream discharge are flatter and flatter and the amplitude of water level and discharge streamwise are decreased by daily regulation. With the advance of power plant discharge flow, instantaneous water slope and velocity before the peak are increased, but reduced after the valley, and then the original relationship between the water slope and discharge is resumed, the maximum water slope before the peak is increased with discharge variability and independent of discharge amplitude, and the sediment transport rate of unsteady flow is greater than steady flow.
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