长江中下游的通江湖泊具有调蓄洪水和涵养水源等重要作用,针对目前通江湖泊分析中将三峡工程作为节点又缺乏支撑性分析的情况,以及对变化环境下江水倒灌年内分配变化规律研究较少的问题,以鄱阳湖为研究对象,采用水文变异诊断系统对鄱阳湖湖口站水位进行变异诊断,并以诊断结果为依据对湖口站实测倒灌序列进行变异前后年内分配变化规律研究。结果显示:变异后汛期鄱阳湖江水倒灌的流量均值上升,但月平均倒灌天数减少,倒灌水量呈减少的态势,且倒灌流量的极值有较大幅度降低,有利于鄱阳湖的防洪安全;非汛期江水倒灌的流量均值、平均天数、流量极值比变异前总体大幅度下降,对于鄱阳湖枯期水位会有较大的影响。研究结果对变化环境下通江湖泊的水情分析具有一定的参考作用。

River-connected lakes in the midstream and downstream of Changjiang River have functions of flood storage and water resources conservation. With the Three Gorges Project as node, current research on river-connected lakes in the midstream and downstream of Changjiang River is in lack of supportive analysis. Research on the annual evolution of backward flow in river-connected lakes under changing environment is insufficient as well. In view of this, the backward flow measured at Hukou Station, Poyang Lake was divided into the series before alteration point and the series after alteration point to study the inner-annual allocation of backward flow. Hydrological Alteration Diagnose System was adopted to analyze the water level series of Hukou Station to uncover the alteration point. Results show that despite increased monthly mean backward flow rate after alteration point, the duration and backflow flow volume both decreased, and the extreme value of backward flow declined dramatically, which was conducive to the safety of flood control of Poyang Lake. The monthly mean backward flow rate, duration, and extreme value of backward flow rate in non-flood season were greatly smaller than those before the alteration point, posing large impact on the water level of Poyang Lake in dry season. The results offer reference for analyzing the water regime of river-connected lakes in changing environment.