An Effect Of The Three Gorges Project On The Ecological Environment Of Dongting Lake Region

Dongting Lake is the second largest freshwater lake in China,it is responsible for multi-task and pressure maintaining the regional water and sediment balance and ecological balance.However, due to the unreasonable development and use, and interference of the human major projects, the ecological environment of Dongting Lake’s wetland has suffered serious damage. Early in the Qing Dynasty, due to the rapid siltation of the sediment, Dongting Lake atrophy from more than6000km2to2600km2. Completion of the Three Gorges water conservancy project can substantially reduce the hazards of floods in Dongting Lake District.However,the large-scale water conservancy project on the ecological environment is comprehensive and far-reaching.Through existing hydrological data and remote sensing data,by using RS,GIS tools and SPSS statistical methods to making a quantitative analysis on Dongting Lake ecological and environmental conditions before and after the completion of the Three Gorges water conservancy project.The method can save a lot of time and money to provide decision-makers operable practical guidance.First of all, the average annual water level and discharge data from 2004-2010was collected,using excel software through traditional statistical methods to calculate the the change trend of the Chenglingji flow calendar year water level from2004-2010,the change of the water level fluctuations during the year and variation rules of each month the water level, the correlation analysis was done and found that regulation of the Three Gorges was little effect on the average annual water level and discharge, but it reduce changes of the water level fluctuation during the year of Dongting Lake, that the maximum water level was lower in the flood season, and the water level has increased compared with before operation in the dry season.Secondly,based on the sediment and runoff data of Dongting Lake from1990-2009,the traditional statistical methods and time series analysis methods is used to obtained the annual sediment load and annual runoff of Dongting Lake over the years changes in the law, and the estimated model is built to observed the Dongting Lake sediment load and runoff changes in short-term. The results obtained that the annual sediment load of Dongting Lake is drop rapidly and the annual runoff of Dongting Lake decrease obviously since the normal operation of the Three Gorges Reservoir in2003. By comparison of goodness of fit and predictive value of relative error, obtained a result that the best prediction model of sediment load and annual runoff of Dongting Lake is ARIMA (0,1,2) and ARIMA (1,1,1).Using Measured values in2009as the validation data, the relative error of the measured and predicted values were11.11%and16.09%, and the measured values all in the predictive value of95%confidence interval.Through proving, ARIMA model to predict good results and it can be applied as an effective tool for short-term prediction of the annual sediment load data and runoff data. Through Forecasting, the annual sediment load data of Dongting Lake from2010to2012is1198.55,1132.64and1068.96; The runoff data of Dongting Lake from2010to2012is2027.36,1996.68and1962.86.Thirdly, using RS\GIS tools to get the classification of remote sensing images of different periods, and extract the wetland landscape types and vegetation information, using the landscape indices and dynamic models to get quantitative analysis of the landscape pattern characteristics and changes, the analysis of landscape pattern changes in the patterns and causes, to explore the impact of the Three Gorges water conservancy project on the landscape and vegetation of the study area wetlands. Found that the landscape pattern of Dongting Lake area is complicate since1989, due to the rapid development of society, urbanization accelerated, and the implementation of the operation of the Three Gorges water conservancy. Dongting Lake wetland landscape fragmentation has gradually increased in the1989-2008; diverse index and both index continued to rise, diverse index increased from0.99to1.05, both index rose from0.61to0.65; Due to the fragmentation level of the landscape pattern was deeper, as well as the shape of patch was unregular, the landscape pattern large patches were cut separation, and crowding level was decreased. Because of the Implementation and construction of the Three Gorges water conservancy project, the vegetation cover of the Dongting Lake area was reduced, vegetation condition was low. As the function of water storage of Three Gorges water conservancy regulation was improved, the water area of Dongting Lake is increased, the area of mudflats, moss marsh land and reed Beach is reduced. Large-scale enrichment planting of a large number of artificial woods, leading to the the shelterbelt beach area continues to increase.Finally, by looking for documents and to gather the related data of Dongting Lake, the impact of the Three Gorges water conservancy project on the shape, biodiversity, floods, and Schistosomiasis Control of the Dongting Lake area are described.