金沙江下游梯级与三峡水库防洪库容互补等效关系研究

长江上游干支流梯级水库和三峡水库均承担着长江中下游的防洪任务,其防洪库容具有一定的互补等效性。本文采用典型年法和最可能地区组成法推求了三峡水库的洪水地区组成,基于不降低原设计防洪标准的原则,探讨了五个典型年和三种设计频率情况下,金沙江下游梯级和三峡水库防洪库容的互补等效关系。结果表明：(1)五个典型年能够反映三峡水库发生大洪水的地区组成规律,金沙江下游梯级和三峡水库防洪库容互补等效关系近似为线性关系。(2)同种典型年和设计频率下金沙江下游四座水库的互补等效系数值近似等同,主要受三峡水库典型年的洪水地区组成影响;当预测洪水主要来源于金沙江(或嘉陵江及未控区间)流域时,等效系数取0.8(或0.5)。(3)通过洪水预报和等效关系动态运用三峡水库防洪库容,在不增加防洪风险的前提下,三峡水库年均汛期可增发电量41.4亿kW·h(+9.86%)。

Complementary and equivalent relationship between the reservoir flood prevention storages of cascade reservoirs in the Downstream Jinsha River and Three Gorges

The cascade reservoirs in the downstream Jinsha River and the Three Gorges Reservoir (TGR) are responsible for the task of flood control in the middle and lower reaches of the Yangtze River, and their flood prevention storages in the upper Yangtze River is complementary and equivalent to some extent.The typical year and most likely regional composition methods were adopted in this paper to analyze the flood regional composition of TGR.Based on the principle of maintaining the original flood prevention standards, the complementary and equivalent relationship between the flood prevention storages in the upper Yangtze River were derived by considering the impact of five typical year flood hydrographs and three design flood frequencies, and the coefficients were quantified.The results reveal that:(1) the five typical years can represent flood regional composition of TGR, and the flood prevention storage complementary and equivalent relationship of cascade reservoirs and TGR is approximately linear relationship.(2) The complementary and equivalent coefficients of the cascade reservoirs under the same typical year and design frequency are almost the same.When the predicted flood mainly originates from the Jinsha River (interval section), the coefficient is taken as 0.8(0.5).(3) By dynamically adjusting the flood control capacity of TGR through flood forecasting and the derived relationships, TGR can increase at least 4.14 billion kW·h (+9.86%) hydropower generation during the flood season on average without increasing flood control risks.