三峡水库防洪作用与鄱阳湖流域洪灾分析

Analysis of flood control function of Three Gorges Reservoir and flood disaster in Poyang Lake Basin

近期,长江中下游洪灾引发国内外网民和社会公众的重点关注和广泛热议,人们认为这是三峡水库不作为造成的。因此,客观、公正、科学地认识长江中下游洪灾,以及评价三峡水库的防洪作用,对稳定社会、人心具有重要现实意义。在介绍长江2020年7月三次编号洪水基础上,分析三峡水库调度过程及其对长江中下游流域的防洪作用与贡献;从气象、水文、地理和防洪标准等角度,揭示鄱阳湖流域洪灾发生的原因。结果表明,三峡水库有效调度了三次编号洪水,削减洪峰幅度为34%~46%,拦蓄洪量为25~88亿m 3,大大缓解了长江中下游防洪压力。鄱阳湖流域洪灾发生的主要原因:一是入梅提前,导致降雨集中强度大、范围广、持续时间长;二是部分支流堤防建设滞后、蓄滞洪区运用不合理,导致上游形成的洪水峰高量大且与鄱阳湖洪水发生遭遇,以及城市加速排洪至河道、中下游长时间处于高水位运行、鄱阳湖受其顶托作用而无法及时通过干流泄洪等。研究结果对正确认识三峡水库的防洪作用与长江中下游流域防洪减灾具有重要参考价值。

Recently, the flood disaster in the middle and lower reaches of the Yangtze River has attracted the extensive attention by netizens and general public at home and abroad. Many people claim that it is caused by the inaction of the Three Gorges Reservoir. Therefore, an objective, fair and scientific understanding of the flood disaster in the middle and lower reaches of the Yangtze River is of great practical significance and scientific value in stabilizing the society and people’s hearts and to evaluate the flood control function of the Three Gorges Reservoir. Based on the introduction to the three floods in the Yangtze River in July 2020, this paper analyzes the operation of the Three Gorges Reservoir and its role and contribution to the flood control in the middle and lower reaches of the Yangtze River. The occurrence of flood in Poyang Lake Basin is revealed from the aspects of meteorology, hydrology, geography and flood control standards. The results showed that the Three Gorges Reservoir effectively dispatched three numbered floods, reduced the peaks by 34%~46%, and blocked the flood volume of 2.5~8.8 billion m3, greatly easing the flood control pressure in the middle and lower reaches of the Yangtze River;the main reasons for the flood disasters in the Poyang Lake Basin are early into the rainy season, high rainfall concentration and a wide range of rainfall and long duration, the construction of some tributary dikes in this area is lagging and the flood storage and detention area is unreasonable, the upstream formation the flood peaks are large and the floods in Poyang Lake have been tragically encountered, the city has accelerated flood discharge to the river and the middle and lower reaches of the Yangtze River have been operating at high water levels for a long time. The research results can be used to evaluate the flood control function of the Three Gorges Reservoir and provide reference for flood control and disaster reduction in the middle and lower reaches of the Yangtze River.