金沙江下游梯级水库运行期设计洪水及汛控水位

Design flood and control water levels for cascade reservoirs during operation periodin the downstream Jinsha River

研究探讨梯级水库运行期设计洪水计算理论和方法,实现防洪和发电效益最大化。采用t-Copula函数建立各分区洪水的联合分布,通过蒙特卡罗法和遗传算法(GA)推求金沙江下游梯级水库的最可能地区组成;分析计算各水库运行期的设计洪水及汛控水位。结果表明:①最可能地区组成结果合理可靠,可为梯级水库运行期设计洪水的分析计算提供依据;②金沙江下游梯级水库受上游水库调蓄影响显著,向家坝水库1000年一遇设计洪峰15400m^3/s(35%),3d、7d和30d洪量的削减量(削减率)分别为35.6亿m^3(33%)、70.2亿m^3(30%)和85.0亿m^3(11%);③在不降低防洪标准的前提下,下游各水库在运行期汛控水位相比汛限水位可适当抬高,白鹤滩、溪洛渡和向家坝水库的汛控水位(汛限水位)分别为788.82m(785m)、570.67m(560m)和371.36m(370m),汛期年均发电量分别增加2.1%、6.1%和1.4%,年增发电量17.1亿kW·h。

This study proposes a design flood estimation method for cascade reservoirs during operation period to maximize the comprehensive benefits both for flood control and hydropower generation.The joint probability distributions of floods occurring at all sub-basins are established using the multivariate t-Copula function. The most likely regional composition is derived using the Monte Carlo simulation and the Genetic Algorithm (GA) methods. The design floods as well as the flood limited water levels of the Wudongde-Baihetan-Xiluodu-Xiangjiaba cascade reservoirs duringoperation period are analyzed. It is shown that:① The results of the most likely flood regional composition are reasonable and can offer a meaningful reference for the analysis of design flood estimation for cascade reservoirs .② The design floods of downstream reservoirs are significantly influenced by the operation of upstream reservoirs. The 1000-year design flood peak,3 d,7 d and 30 d design flood volumes at Xiangjiaba reservoir significantly decrease by 15 400 m^3 /s (35%),3.56 billon m^3(33%),7.02 billon m 3(30%) and 8.50 billion m^3 (11%),respectively .③ The obtained flood control water levels of downstream reservoirs are slightly higher than flood limited water levels but without reducing the original flood prevention standards. The flood control water levels (flood limited water levels) of Baihetan,Xiluodu and Xiangjiaba reservoirs during operation period are 788.82 m(785 m)、 570.67 m(560 m) and 371.36 m (370 m),which can increase the hydropower generation by 2.1%,6.1% and 1.4%,respectively,and in total 1.71 billion kW·h annually.