Debris flow prediction and prevention in reservoir area based on finite volume type shallow-water model: a case study of pumped-storage hydroelectric power station site in Yi County, Hebei, China

In recent years, the development of pumped-storage hydroelectricity has seen a very rapid increase, and lots of stations have been proposed to be built in China to adjust the energy structure of production and alleviate electrical energy shortages. The site of pumped-storage hydroelectric power plants is usually chosen in the mountain area, which can conveniently provide headwaters and height difference for the proper functioning of hydroelectric power station; however, geological disasters such as debris frequently flows in the mountain areas, posing great threat to the safety of plants and staff. A large pumped-storage hydroelectric power station will be built in the Taihang Mountains in the northwest of Yi County, Hebei province. To predict the potential scale of debris flow hazard, the shallow-water model based on the finite volume method (SFLOW model) is used. During the work, reconnaissance, geomorphological analysis, and laboratory experiment are carried out for model construction and data input. Then the debris flow designed for 20-, 50-, 100-, and 200-year return periods and the flood caused by dam break are simulated. The simulation study shows that the potential debris flow hazard will greatly harm the reservoir area, and if debris flows destroy the dam, floods could affect the residents of a maximum of 1.21 million square meters downstream. To prevent debris flows, retaining walls in the SFLOW model are set, and the results show that they can effectively reduce the hazard area of debris flow, ensuring the safety of the reservoir area. In general, the SFLOW model can accurately and efficiently solve the problem of fluid flow on irregular terrain and can be applied to similar engineering projects.