考虑提前蓄水的高坝后期导流风险效益分析

后期导流过程中采用提前下闸蓄水方式,可获得更多发电收益。然而这一措施会在汛期增加大坝施工期漫顶风险,并加大满足蓄水要求的赶工成本,使导流方案决策更为复杂。本文以高坝施工期安全度汛为研究对象,考虑水文、水力不确定性,模拟不同初期蓄水下闸方案的导流风险率;针对不同下闸时机和蓄水保证率,计算蓄水历时、提前蓄水的发电增量和发电效益;综合后期导流风险概率、发电效益和下闸蓄水赶工成本要素,建立后期导流方案多目标决策模型,寻求提前下闸蓄水时机。通过雅砻江流域某在建大型高坝工程实例分析表明,该方法能综合评价提前下闸蓄水方案的经济性和风险情况,在此基础上寻求理想下闸时机。研究为高坝后期导流施工决策提供了理论和实践依据。

Risk-benefit analysis of late stage diversion for high dams impounding water in advance

In late stage diversion, more power generation benefit can be achieved by impounding water earlier. However, in flood season, this measure will increase the risk of overtopping during dam construction and add the cost for accelerating progress to meet the early impoundment goal, making diversion decision more complicated. In this study, we simulate the diversion risk rates of dam construction in different schemes of initial water impoundment, considering hydrological and hydraulic uncertainties and flood prevention during dam construction. And we calculate impoundment duration, power generation and generation benefit for different impoundment schemes and different guarantee rates. Through a comprehensive consideration of the risk rate, power generation benefit and construction cost, we develop a multi-objective decision model for seeking a satisfactory start timing of dam impoundment. A case study of an under-construction dam on the Yalong River shows this method can give a comprehensive evaluation on the economic benefit and risk of early impoundment schemes aimed at finding reasonable impoundment timing.