Abstract:

The Three Gorges Project launched in 1993 and completed in 2008.Since 2006, the water level of the Three Gorges Reservoir reached the predetermined 135 meters,and the Three Gorges Project began to pay dividends this year,playing an important role in flood control,power generation,navigation,water diversion and environmental protection.On November 4,2008,the water level of the Three Gorges Reservoir reached 172.5 meters;on October 29,2009,the water level reached 170.9 meters;on October 26,2010,the water level eventually reached 175 meters.The Yangtze River and its branches of the reservoir area of the Three Gorges began to store water and turned into a reservoir in mid June,2003,and the water level reached 170 meters in 2008.The flow rate of the Yangtze River slowed down after construction of the reservoir.As well as producing electricity,the Three Gorges dam is intended to increase the Yangtze River shipping capacity and reduce the potential for floods downstream by providing flood storage space.The Chinese government regards the project as a historic engineering,social and economic success,with the design of stateoftheart large turbines,and a move toward limiting greenhouse gas emissions.However,the dam flooded archaeological and cultural sites and displaced some 1.3 million people,and is causing significant ecological changes,including an increased risk of landslides and algae bloom.The dam has been a controversial topic both in China and abroad.In order to study the algal bloom of the branch river of the Three Gorges Reservoir and realize ecologic regulation of the Three Gorges reservoir ，the influence of the 175 m trial impoundment of the Three Gorges Reservoir on water environment was conducted.The Three Gorges Reservoir (TGR) began to 175 m experimental water storage in 2008-2010.The impoundment scheme of Three Gorges Project(TGP) was different in 2008-2010. The field environmental monitoring data used in this paper was from the XiangXi Bay from 2008 to 2010.This article carried out the analysis from the aspects of water bloom outbreak degree, water quality and hydrodynamic and so on,aftertwards described the influence of the different impoundment scheme of the 175 m trial impoundment of the Three Gorges Reservoir on water environment in the Xiangxi Bay. The results showed that the time of water storage advanced was beneficial to upper water exchange and turbulence of the upstream of Xiangxi Bay(XXB) , reduce the water surface nutrient concentration, destroy the living environment of phytoplankton,restrain the growth of algae, reduce the water surface of chlorophyll a concentration,and decrease water bloom outbreak frequency, duration, and strength. These are beneficial to the improvement of the water environment in Xiangxi Bay