Hydrogeology of Shuikou Hydropower Station

Shuikou Hydropower Station is located on the main stream of Minjiang River in Minqing County, Fujian Province. Its upstream is 52,438 square kilometers away from the dam site of Shuikou Hydropower Station in Nanping City, accounting for 86% of the total area of Minjiang River basin. There is abundant rainfall in the basin, with an annual average rainfall of 1.758 mm, an annual average flow of dam site of 1.728 m3/s, and an annual total runoff of 54.5 billion m3. The measured maximum flow is 30,200 m3/s, and the minimum flow is 1.96 m3/s. The maximum flood peak flow in the investigation history is 38,500 m3/s. The once-in-a-thousand flood peak flow of the dam site is 46,700 cubic meters per second, and the once-in-a-million flood peak flow is 55,400 cubic meters per second. The average sediment concentration of the dam site for many years is 0. 143kg/m3, and the average suspended sediment transport for many years is 7 18000 t ... The reservoir area is composed of insoluble magmatic rocks and clastic rocks, so there is no permanent leakage problem and no major instability problem of the reservoir bank. The dam site is Mesozoic Yanshanian biotite granite with hard and complete lithology, and the average wet compressive strength is generally above 100MPa. No major structural faults are found in the dam site area, but only a few small faults, compression fracture zones and weathering fracture zones are found in the riverbed, which are small in scale and steep in dip angle. There are gently dipping joints along the river, but they are not deeply developed, which has little impact on the project. The thickness of dam site overburden is generally 5 ~ 10m, and there are deep bedrock grooves on the river bed, and the thickness of alluvium reaches 29m. The bedrock under the deep trough is fresh and complete, and no structural cracks are found. Appraised by the Seismological Bureau of Fujian Province, the basic earthquake intensity in the dam area is 7 degrees. When the normal water level of the reservoir is 65m, the reservoir areas of Minqing, Gutian, Youxi and Nanping are flooded. According to the 20-year flood standard, 63,495 people need to be relocated; According to the calculation of once-in-20-year flood, it is necessary to requisition 3 1.394 mu of cultivated land.