近30年鄱阳湖与洞庭湖水文变化与归因

Hydrological variations and attribution analysis of Poyang Lake and Dongting Lake in the past 30 years

为揭示鄱阳湖和洞庭湖水文特征并综合分析其影响因素对湖泊水资源管理及江湖关系,以两湖水系统为研究对象,采用非参数秩次相关检验法(Mann-Kendall M-K)分析方法和近30年两湖-流域-长江水位和流量长序列数据集,解析湖泊水文变化特征、趋势和程度,并通过两湖水文的对比来系统分析长江中游大型通江湖泊水文变化规律及其影响因素,旨在对两湖流域水资源的整体认识和把控,丰富对江-河-湖复杂水系统作用机制与内涵的深入理解。结果表明:两湖水位在近30年总体上呈"上升-非稳定状态-下降"3个变化阶段。2003年前,鄱阳湖和洞庭湖水位总体呈上升趋势,且在1980-2000年间基本处于不稳定的波动状态,2003年后两湖水位呈明显的下降趋势。Mann-Kendall分析得出:两湖水位可能在2005年左右发生明显突变,且鄱阳湖和洞庭湖水位与之前相比,最大降幅分别可达9.4%和3.4%,表明两湖水位变化的趋势程度存在差异,鄱阳湖水情变化的敏感程度要强于洞庭湖。对长江干流的补水期洞庭湖为4-10月,鄱阳湖为3-8月,表明两湖对长江干流水文的不同调节补偿作用。

Poyang Lake and Dongting Lake are currently one of the few large and natural river systems in China that play an irreplaceable role in regulating the flood and maintaining the ecological environment of the Yangtze River Basin.In recent years,due to the superimposed influence of climate change and large-scale water conservancy projects,the change of the hydrological situation of the two lakes has gained considerable attention.Therefore,it is of great practical significance to reveal the hydrological characteristics of the two lakes and comprehensively analyze the influencing factors for the in-depth understanding of the lake water resource management and the relationship between the rivers and lakes.Taking the water systems of Dongting Lake and Poyang Lake as the research objects,the Mann-Kendall test is used to study the trend and degree of lake water regime evolution through the water level of the two lakes,the runoff of the Yangtze River and the runoff of the two lakes in the past 30 years.Moreover,the overall variation characteristics of hydrological variables in both lakes and their causes at different periods in1985-2014 are analyzed.Through the comparison of the hydrological conditions in both lakes,the law of hydrological variation and its influencing factors in the river-connected lakes in the middle reaches of the Yangtze River are systematically examined.The results show that the water levels of the two lakes in the past 30 years have generally been in three stages of "rising-unsteady-declining".Before 2003,the water levels of Poyang Lake and Dongting Lake generally showed an upward trend,and they are basically in an unstable fluctuation state from 1980 to 2000.After 2003,the water level of the two lakes showed an obvious downward trend.Mann Kendall analysis showed that the water level of the two lakes may have a significant mutation around 2005,and the maximum drop of the water level of Poyang Lake and Dongting Lake is 9.4% and 3.4%,respectively,compared with the previous one,indicating that the trend degree of water level change of the two lakes is different,and the sensitivity degree of water regime change of Poyang Lake is stronger than that of Dongting Lake.The replenishment period of Dongting Lake for the mainstream of the Yangtze River is from ApriltoOctober,and for Poyang Lake is from MarchtoAugust,indicating that the two lakes have different adjustments and compensation effects on the hydrology of the mainstream of the Yangtze River.