近60年来长江对鄱阳湖倒灌水量的变化特征

鄱阳湖是长江中下游典型的通江湖泊,其出流特征及水位涨落同时受五河及长江来水的双重影响,进而形成较为复杂的江湖水文情势关系。为研究长江对鄱阳湖作用的变化规律,依据鄱阳湖五河以及出湖控制水文站1956—2016年水文数据,探讨长江对鄱阳湖倒灌水量的变化规律。研究结果表明:鄱阳湖五河七口控制站2003—2016年年平均径流量相比1956—2002年有所降低。鄱阳湖倒灌水量、倒灌天数均与汉口站来水和鄱阳湖入湖水量之差呈较好的正相关关系。2003年后,三峡水库的蓄水或放水在一定程度上影响了江湖作用的季节变化和鄱阳湖流域的旱涝机遇,一定程度上减少了长江对鄱阳湖的倒灌频次。通过对倒灌水量和倒灌天数的分析可知,在1960年代、1980年代和21世纪初,长江上中游来水对鄱阳湖的作用相对强烈;而在1970年代、1990年代和2010年以后,长江上中游来水对鄱阳湖作用较弱。研究成果对于认识变化条件下长江与鄱阳湖江湖关系变化规律具有重要意义。

Variation Characteristics of Water Recharge from Changjiang River into Poyang Lake

Poyang Lake is a typical lake that links to rivers in the middle and lower reaches of the Changjiang River. The outflow characteristics and water level fluctuation of Poyang Lake are affected by the flow from Ganjiang River, Fuhe River, Xinjiang River, Raohe River, Xiushui River and the Changjiang River, forming a complex hydrological relationship between rivers and lakes. According to hydrological data of the aforementioned five rivers and the control hydrological station of Poyang Lake from 1956 to 2016, we probed into the variations of water recharge from the Changjiang River into Poyang Lake via wavelet analysis and other methods. Research results revealed that the average annual runoff from 2003 to 2016 was lower than that from 1956 to 2002. The volume and number of days of water recharge are both positively correlated with the difference between the streamflow of Hankou Station and the amount of runoff entering Poyang Lake. After 2003, the impounding or releasing of the Three Gorges Reservoir has, to some extent, affected the seasonal changes of the rivers and lakes and the drought and flood opportunities in the Poyang Lake Basin, and further reduced the frequency of water recharge from the Changjiang River into Poyang Lake. In the 1960s, 1980s and early 21st century, the incoming flow from the upper and middle reaches of the Changjiang River exerted strong influence on Poyang Lake; and in the 1970s, 1990s and 2010s, such influence weakened. The research findings are of great significance for understanding the relationship between the Changjiang River and the Poyang Lake under varying circumstances.