| With the completion of the Three Gorges Project, water impoundment operations have been smoothly for some years now. The Three Gorges Project has also had a broad and far-reaching impact on the ecological environment, with tremendous social and economic benefits. This paper is based on the different social and economic conditions, which will result in different characteristics of land use change. In this paper, landscape pattern changes can be illustrated by land use changes, and the changes in ecological index can be analyzed with remote sensing. This paper based on the changes of TN and TP to illustrate the non-point source pollution.The land use interpretation of the 4 phase of the study area in 2001, 2007, 2010, and 2014 was carried out firstly, and verified the accuracy of interpretation by field reconnaissance survey. On this basis, this paper analyzed the variation of landscape pattern of 4 typical districts, based on some means of the theory of landscape ecology, GIS, statistical analysis technique and software such as Fragstats 4.2, ArcGIS 10.1, SPSS 20.0. And carried out the remote sensing monitoring and analysis of the study area in 2001, 2007 and 2014 by GIS software. Finally, by analyzing the changes in the total amount and spatial distribution of TN and TP, this paper revealed the ecological environmental evolution in the study area. The result provides theoretical basis for the optimization of the reservoir area of land use and ecological control.The main contents and conclusions are as follows:(1) The variation of land use type mainly shows the increase of farmland and decrease of woodland and meadow in Jiangjin, farmland has increased 409.77km2. The land use change is not obvious in Zhongxian during the2007 to 2010, farmland increased by 20.88km2. The area of farmland decreased by 155.70km2, the policy of returning farmland to forest in the area of effect is obvious in Fengjie. The area of farmland in Shapingba decreased year by year, in 14 years the area decreased by 84.03 km2, construction land area increased, urban development fast.(2) The Remote Sensing Ecological Index(RSEI) was constructed by four indexes of humidity, dryness, heat and green degree, and the ecological environment evolution of study areas in 2001, 2010 and 2014 was quantitatively evaluated. The mean value of RSEI was increased in Fengjie and Shapingba, ecological environment quality get better. The mean value of RSEI was decreased in Jiangjin District and Zhongxian, ecological environment quality get worse. On the county ecological remote sensing index classification evaluation that 2014 Fengjie, Zhongxian and Shapingba mainly in 4(good), 5(better), Jiangjin mainly in 2(poor) and 3(medium). Through the remote sensing change detection analysis of the study area, to further verify the results of the changes in the ecological environment quality.(3) This paper took the typical land use variation mode and social economic background into consideration, using the dynamic export coefficient model, the spatial variation of non-point source TN and TP under the affect of changing land using type from 2001 to 2014 was analyzed. The TN load in Shapingba is reduced by 50.52%, TP reduced by 39.34%, the non-point source pollution TN, TP load in Jiangjin increased by 93.56% and 74.30%. In Fengjie and Zhongxian, the non-point pollution TN increased by 25.20% and 42.71%, TP increased by 25.10% and 36.52% during 14 years.(4)The three angles from the description of changes of ecological environment in the study area, basically the same conclusion. For Jiangjin and Zhongxian three aspects to prove that the decline of ecological environmental quality, and Shapingba becomes better. Only the rule of Fengjie county is not obvious. This shows that the above three methods have a certain scientific on the description of the evolution of the ecological environment. |
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