2018长江2号洪水期间三峡水库沙峰排沙调度

Analysis of sediment peak scheduling of Three Gorges Reservoir in No.2 flood of Changjiang River in 2018

2018年长江第2号洪水期间,寸滩站洪峰流量59 300 m^3/s,报汛最大含沙量达到4.47 kg/m^3,三峡入库沙量达到了7 440万t,均大于2014~2017年各年的全年入库输沙量,且入库沙峰大、持续时间长。根据泥沙实时监测与预报成果,7月11～20日三峡水库入库和坝前含沙量较大,三峡水库在进行防洪、航运调度的基础上,实施了沙峰排沙调度,将下泄流量42 000 m^3/s一直维持至沙峰通过大坝后。实测资料表明:7月18～20日三峡水库排沙效果明显增强,出库含沙量在0.50～1.20 kg/m^3之间,最大出库输沙率达到48.5t/s,日均出库沙量在370万t左右,按沙峰输移过程统计,沙峰过程排沙比达29%,7月份排沙比达到了31%,取得了较好的排沙效果,有效减轻了库区泥沙淤积。研究成果为进一步完善三峡水库"蓄清排浑"新模式积累了宝贵的经验。

During the period of No.2 flood of Changjiang River in 2018,the peak discharge at Cuntan Station was 59 300 m^3/s with the maximum sediment concentration of 4.47 kg/m^3,and the sediment into the Three Gorges Reservoir reached 74.4 million tons with a high sediment peak and a long duration,which were larger than the annual amount from 2014 to 2017.Through the real-time sediment monitoring and sediment forecasting,the sediment concentration of incoming and in front of the dam were relatively large from July 11 to 20.On the basis of flood control and shipping operation,we carried out desilting dispatch for the Three Gorges Reservoir by maintaining the discharge flow at 42 000 m^3/s until the sediment peak passed through the dam.The results show that the sediment discharge effect of the Three Gorges Reservoir was significantly enhanced from July 18 to 20 with the discharging sediment concentration of 0.50~1.20 kg/m^3,the maximum sediment discharging rate reached 48.5 t/s and the average daily discharge was about 3.7 million tons.According to the statistics of the sediment peak discharging process,the sediment peak discharge ratio reached 29%in the No.2 flood and 31%in the whole July,obtaining satisfied sediment discharging effect and effectively alleviating the sediment deposition.It has accumulated valuable experience for further perfecting the new model of"storing clear and releasing muddy"of the Three Gorges Reservoir.