三峡工程运行以来洞庭湖水沙过程变异及其影响分析

为了探讨三峡工程运行后洞庭湖区水沙条件变化及其对江湖关系、水情响应、冲淤变化等的影响，以水沙过程变异为主线，利用最新水沙观测资料，采用水文描述法、变差系数法、双累积曲线法、数学计量等方法分析了洞庭湖区水沙变异特征和江湖水沙交互关系，结果表明:（1）从年际和代际尺度上看，长江上游降水量减少和三峡工程建设等人类活动是影响洞庭湖水沙变异的主要因素；（2）洞庭湖流域外界环境的变化导致了三口分流分沙的锐减，并呈现三口口门趋于淤积的状态，藕池河和虎渡河逐渐走向衰亡；（3）从洞庭湖泥沙沉积量过程线来看，2003—2011年洞庭湖的累计泥沙淤积量仅为3 411万t，比多年平均值减少93.5%。

Water and Sediment Process Variation and Impact Analysis of Dongting Lake Since the Operation of the Three Gorges Project

In order to discuss the changes of erosion, hydrological response, relationship between river and lake, variation of the condition of water and sediment of the Dongting Lake area since the operation of the three gorges project, this paper took the water and sediment process variation as the main line, made full use of the existing and the latest observation hydrology and sediment hydrological data of Dongting Lake, applied hydrological method, variation coefficient method, double accumulated curve method, mathematics computation method, analyzed the interactive relationship of the Dongting Lake water and the Yangtze River, and the variation features of the flow and sediment of the Dongting Lake. It was concluded that the following main conclusions: (1) judging from the inter-annual and inter-generational scale, precipitation reduction of the upper reaches of Yangtze River and Three Gorges Project construction are the main factors of the flow and sediment variation of the Dongting Lake; (2) the sharp decline of flow and sediment of the three outlets of Jingjiang River due to the changes in the external environment of Dongting Lake basin, and the three outlets tend to siltation, Ouchi River and Hudu River are gradually demise; (3) from the amount of sedimentation process line of the Dongting Lake, the amount of accumulated sediment deposition of the Dongting Lake in 2003—2010 is merely 3.411×10⁷ t, reduced by 93.5% than the average for many years.