白格堰塞湖对金沙江水沙及梯级水库运行的影响

2018年金沙江上游白格滑坡造成了近百年来最为严重的干流堵江事件,堰塞湖的形成和溃决给下游金沙江干流河道的水沙条件及梯级水电站运行造成影响.本文依据堰塞湖附近临时观测和金沙江干流河道控制性水文站的相关资料,研究堰塞体泄流对下游河道水沙输移的影响,同时结合梯级水库调度情况,计算了梯级水库的拦沙量.结果表明,堰塞湖溃决在金沙江中游形成了超历史的水沙过程,金沙江中游梯级电站开展应急调度后,堰塞湖溃决造成的特大洪水被削减为一般洪水.金沙江中游梯级梨园、阿海和金安桥电站累积拦截泥沙约1400万t,龙开口、鲁地拉和观音岩电站共计拦截泥沙约43万t,滑坡体产生的泥沙仍有约74%滞留在堰塞体附近.若滑坡体泥沙全部输移至金沙江中游梯级水库内,梨园电站的有效库容极有可能不满足水库所需调节库容的要求.

Effect of Baige landslide-dammed lake on runoff and sediment of the Jinsha River and operation of cascade reservoirs

Baige landslide occurred in the upstream of Jinsha River in October 10, 2018 caused the most serious river blockage event in the recent hundred years. Formation and breaking of the Baige landslide-dammed lake (BLDL) had unknown effects on water and sediment conditions and the operation of cascade hydropower stations in the main stream of the downstream Jinsha River. Based on the observational data of the temporary gauge station near the BLDL and the controlled hydrological stations in the main trunk of Jinsha River, the effects of BLDL on water and sediment conditions in the middle and lower Jinsha River are studied. Combining with the operation of cascade reservoirs before and after the breaking of the landslide-dammed lake, the sediment retention amount of cascade reservoirs is estimated. The results showed the breaking of the BLDL formed a super-historical hydrograph of water and sediment in the middle Jinsha River. After the emergency regulation of cascade reservoirs in the middle Jinsha River, the extraordinary flood caused by the outbreak of the BLDL was reduced to a normal flood. Nearly 26% of the sediment generated by landslides is transported and deposited in cascade reservoirs in the middle Jinsha River. Among them, the Liyuan, Ahai, and Jinanqiao hydropower stations intercepted about 14 million tons of sediment, while Longkaikou, Ludila, and Guanyinyan hydropower stations intercepted about 0.43 million tons of sediment. About 74% of the landslide-induced sediment remains near the Baige barrier. Given that all the sediments generated by the Baige landslide are transported into the cascade reservoirs along the middle Jinsha River, the effective reservoir capacity of Liyuan hydropower station will probably not meet the requirement of the reservoir regulating capacity.