川渝河段梯级水库联合防洪调度风险评价

Risk Assessment of Joint Flood Control Operation of Cascade Reservoirs in Sichuan-Chongqing Reach

金沙江下游四座梯级水库联合调度防洪风险评价能科学地衡量其防洪风险性,为长江中下游川渝河段的防洪安全提供保障。针对防洪调度中的风险问题,基于联合防洪调度方案,通过建立以削峰幅度、防洪风险率、水位变幅和下泄流量超标风险率为指标的风险评价体系,并采用蒙特卡罗法进行风险模拟,构建了基于灾害学的防洪调度风险评价模型,评估了不同来水频率和水库起调水位下的防洪风险。研究表明:在可行起调方案集下,乌东德、白鹤滩两库的削峰幅度随两库起调水位升高呈下降趋势,溪洛渡、向家坝两库削峰幅度在7%以下,金沙江下游梯级水库的入库洪水危险性小;各水库未出现最高库水位超出相应频率防洪高水位(乌东德975 m,白鹤滩825 m,溪洛渡600 m,向家坝380 m)的情况,水库的水位变幅均未超过安全变幅范围,库区整体防洪风险低,川渝河段的防洪风险在可控范围内;当发生较小洪水时下游防护对象的承灾能力较好,保护区控制站的下泄流量低于防洪安全标准值,下游防护对象的防洪风险低,但发生干支流恶劣洪水遭遇(如2012年型1%洪水)时,其遭遇破坏的可能性大,风险超出防洪标准,保障防洪安全需要支流水库配合干流水库联合防洪。模型可有效评估川渝河段防洪调度风险,为地区防洪调度风险研究和决策提供参考。

The evaluation of the flood control risk of the joint operation of the four-level cascade reservoirs in the lower reaches of the Jinsha River can scientifically measure the risk of flood control and provide guarantee for the flood control security in the Sichuan-Chongqing sec⁃tion of the middle and lower reaches of the Yangtze River.In view of the risk problems in flood control operation,based on the joint flood con⁃trol operation scheme,a risk assessment model of flood control operation based on disaster science is constructed,by establishing a risk as⁃sessment system with peak cutting amplitude,flood control risk rate,water level variation amplitude and the risk rate of discharge exceeding the standard,and using Monte Carlo method for risk simulation.The flood control risk results of the reservoir under different inflow frequen⁃cies and reservoir levels are evaluated.The results show that under the feasible starting scheme set,the peak cutting amplitude of the Wudongde and Baihetan reservoirs decreases with the increase of the lifting water level of the two reservoirs,and the peak cutting amplitude of the Xiluodu and Xiangjiaba reservoirs is less than 7%,and the flood risk of the cascade reservoir in the lower reaches of Jinsha River is small.The maximum reservoir water level did not exceed the corresponding frequency of flood control high water level(975 m in Wudongde,825 m in Baihetan,600 m in Xiluodu,380 m in Xiangjiaba)in all reservoirs,and the variation of reservoir water level did not exceed the safe variation range.The overall flood control risk of the reservoir area is low,and the flood control risk of the Sichuan-Chongqing reach is within the controllable range.When there is a small flood,the disaster bearing capacity of the downstream protection objects is better,The discharge flow of the control station in the protected area is lower than the standard value of flood control safety,and the flood control risk of downstream protection objects is low.But when there is a bad flood in main and tributary streams(such as the 1%flood in 2012),the possi⁃bility of damage is high,and the risk exceeds the flood control standard.To ensure flood control safety,the joint flood control of tributary res⁃ervoirs and main stream reservoirs is required.The model can be applied to the flood control operation risk assessment of cascade reservoir ef⁃fectively,and provide reference and basis for regional flood control operation risk research and decision-making.