Effect Of The Three Gorges Project On The Water Environmental Of Dongting Lake And Its Countermeasures Research

Dongting Lake is one of the most famous lakes in China, accept the Yangtze River and the Xiang,Zi,Yuan,Li River. The annual throughput reaches 300 billion cubic meters which is 3 times bigger than Boyan Lake,5 times bigger than Yellow River,10 times bigger than Tai Lake. Due to its multiple functions,the Dongting Lake plays an irreplaceable role in regulating the ecological environment of Yangtze River and it was known as "the stomach of Yangtze River".The Three Gorges Project makes a tremendous impact on the environment of Dongting Lake since the Yangtze River is Closely related to Dongting Lake.After the project putting into operation,its water storage and regulation function makes the former relations between rivers and lake have undergone significant changes, it also changed the hydrology and water quality a lot and gave a further influence over the water environment of Dongting Lake. By comparing the sedimentation rate and other indicators of confirmed that increased water pollution, eutrophication level already haveThis thesis start with the basic concept of the water environment and the ecological environment, it was found that with the high speed economic and social development in the Dongting Lake region, the water environmental problems appeared gradually, for instance, the water eutrophication, excessive heavy metal contamination,a serious decline in water level, the capacity declined significantly, and the most prominent problem is an inadequate water supply in lake district.Through more than 10 times Dongting Lake region field trips investigation, compared to the years of hydrological data, laboratory testing,and use of 3S techniques, it was found that especially after the operation of the Three Gorges project, the water consumption comes from three water entry,Songzi,Ouchi,Taiping along Yangtze River,had decreased by 40%,the sediment also reduced by 85%; increasing water pollution, and simulation typical critical loads of Nitrogen found that,Dongting Lake would have the eutrophication; groundwater levels declining day by day,the lake area decreased by 30% or more.In view of existing situation, this thesis introduced the concept of the lowest ecological water level for the first time. Through the natural water level data analysis,morphological analysis lakes, the minimum requirements ecological space three calculation methods, obtain results that the lowest ecological water level of Dongting Lake should be controlled at 24 meters and above, and estimated the water shortage of Dongting Lake in the dry season was at least 400 million cubic metres.In order to solve this problem, in this thesis, we proposed six practical and feasibility measures:the construction of water projects, improve policies and regulations, the establishment of coordinating agencies, the adjustment of the industrial structure and multi-center treatment.Sluice integration project at Chenglingji, was in conformity with the assume that building a sluice in Songzi estuary which proposed by Provincial Committee and the Provincial Government, which can solve the water shortage situation in Dongting Lake effectively, made the Water Environmental Treatment of Dongting Lake as a long-term research projects.