Discussion on Discharge Scale and Future Operation of Sanmenxia Project

摘要

At the preliminary stage of water storage, sediment trapping, flood detention and sediment releasing of Sanmenxia Multipurpose Project, the scale of low - level discharge is small, flood and sediment detention is notable, which resulted in a great rising of elevation at Tongguan. After upgrading, redeveloping and discharge enlarging of the Project, the elevation at Tongguan was once kept basically balanced for a long time (1973 ～ 1986) . In the recent decades of years, the elevation at Tongguan keeps rising or remains high without decreasing, which does not basically come from the small discharge scale but mainly comes from the large reduction of floods and the inflow in flood season. The discharge in the recent years in flood season has not reached the design level, therefore, the flood and sediment detention for general flood does not appear basically. Comprehensive measures must be taken to lower the elevation at Tongguan through. Based on the analysis of research results of riverbed erosion at Tongguan and the reservoir sediment releasing capacity in different discharge grades in flood season, it is proper that the highest operation water level of the reservoir in non - flood season shall not exceed 320 m and not affect the river reach from Tongguan to Guduo. The least discharge for sediment releasing in flood season can be lowered to 1, 500～2,000 m~3/s and the lowest water level for it can be lowed to 292 ～ 294 m. The reservoir level can be properly raised in ordinary or low flow and at the end of flood period to realize comprehensive benefits of the Project.