水库汛限水位动态控制预泄能力约束法的必要条件

Necessary condition of constrained pre-discharge capacity method for dynamic control of reservoir flood limit water level

水库汛限水位动态控制是水资源利用和防洪中的研究热点之一。然而,预泄能力约束法下,水位动态控制域与预报预泄期洪水过程的数量关系尚未探明,这为在变化环境下开展汛限水位动态控制留下了防洪隐患。以万安水库汛期动态控制上下限研究为例,通过涨速量化分析方法,研究了预报预泄期大洪水涨速对水位动态控制域推求的影响。结果显示,万安水库控制上限与预泄末期18~48 h时段内洪水起涨平均上涨率呈十分显著的负相关,即,5场典型50 a一遇设计洪水预泄末期48 h起涨速率分别为334 m^(3)·s^(-1)·h^(-1)、522 m^(3)·s^(-1)·h^(-1)、468 m^(3)·s^(-1)·h^(-1)、1043 m^(3)·s^(-1)·h^(-1)、812 m^(3)·s^(-1)·h^(-1),相应推求的上限水位分别为93.6 m、92.2 m、91.0 m、88.5 m、89.4 m。上述结果表明,大洪水预报预泄期洪水过程(涨速)对确定水库汛期动态控制域具有决定性作用,是实施水库汛限水位动态控制预泄能力约束法的必要条件。在变化环境下,本研究对完成防洪任务、争取发电效益具有十分重要的价值。

Dynamic control of reservoir flood limit water level is one of the study hotspots in the aspects of water resources utilization and flood control.However,the quantitative relationship between the dynamic control domain of water level and the flood hydrograph of the forecasted pre-discharge period is not yet ascertained under the constrained pre-discharge capacity method,which leaves a hidden danger of flood control for the dynamic control of flood limit water level in the changing environment.By taking the study on both the upper and the lower limits of the dynamic control of Wan′an Reservoir during flood season as the study case,the influence of the flood rising speed during the period of the forecasted pre-discharge on the derivation of water level dynamic control domain is studied herein through the quantification analysis of the flood rising speed.The result shows that the upper control limit of Wan′an Reservoir significantly exhibits a negative correlation with the mean rising speed rate in the last phase of the pre-discharge period of 18 h~48 h;namely,the 48 h-flood rising rates of the last phases of the-pre-discharge period of five typical design floods with the return periods of 50 years are 334 m^(3)·s^(-1)·h^(-1),522 m^(3)·s^(-1)·h^(-1),468 m^(3)·s^(-1)·h^(-1),1043 m^(3)·s^(-1)·h^(-1),812 m^(3)·s^(-1)·h^(-1)respectively,while the corresponding deduced upper limit water levels are 93.6 m,92.2 m,91.0 m,88.5 m and 89.4 m,respectively as well.The above-mentioned results show that the flood hydrograph(rising rate)of the forecasted pre-discharge period of great flood plays a decisive role in determining the dynamic control domain of reservoir during flood season and then is a necessary condition for implementing the constrained pre-discharge capacity method of the dynamic control of the flood limit water level of reservoir.In the changing environment,this study has a great value to accomplish the task of flood control and strive for the benefit of power generation.