Sediment Transport and its Effect on Navigation in Long Tailrace of Hydropower Station

Abstract

Using long tailrace channel to navigate is a complex development way which has a common channel for navigation and tailrace. It is gradually tried to use in the Angu hydropower station and Shawan hydropower station of the Dahu River. So the flow and sediment movements are the key and decisive factors for navigation safety. Some achievements have been obtained about the influence of unsteady flow to navigation in tailrace channel. But it is very few to study that of sediment movement. Use the Angu hydropower station as an example, sediment movement is studied in long tailrace channel. Firstly, sediment sources are analyzed by measured data. Secondly, a two-dimensional sediment model and the experience formula are also used to simulate the transport of sediments. The transports of suspended load and bed load are studied with different operation of the hydropower station. Finally, with the typical series of 20 years, which includes high flow year, mean flow year and low flow year, riverbed deformation is predicted in the mooring area, the tailrace channel and its outlet. And the effect on navigation is analyzed. The results show that sediment sources are dominated by the local sediment. The deposition in the tailrace channel is not large and has little influence to navigation safety. A small amount of dredging can meet the needs of maintenance. The research results are helpful to the design and operation of long tailrace channel.