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—2010is merely 3.411×107 t,reduced by 93.5% than the average for many years.