Evaluation Of Basin's Ecological Sensitivity

With the social development and technological progress, the scope and intensity that the human impacted on the natural environment are constantly increasing, resulting desertification, salinization, soil erosion, acid rain and other environmental problems have also been expanded and intensified. These regional ecological and environmental problems are serious threat to human survival resources, such as atmosphere, land and water. Economic losses that caused directly and indirectly each year are considerable. In China, the economic loss caused by wind and sand damage every year reach 4.5 billion Yuan; soil erosion caused are more than 10 billion Yuan; and the economic losses caused by acid rain are as much as 1.4 billion Yuan. It has seriously affected the capacity for sustainable development. Therefore, environmental problems of the prevention and remediation have become very urgent.In recent years, the development of Chongqing's economic is more rapidly, and GDP average annual growth rate is reach to 10.1%.So, environmental problems are more serious, especially soil erosion, acid rain, water pollution and other issues. Jialing River as one of most important tributaries of the Yangtze River, its ecological environment qualities will directly affect the water quality of Yangtze River. Because of the changes in the natural environment and the increase of human activities intensity along the Jialing River in recent years, the degenerated ecological environment qualities are seriously affects people's survival and socio-economic development, and threatened the basin's ecological and environmental security. Thus, this section of Chongqing downtown along the Jialing River is selected as the study area, combined with Jialing River basin's practical characteristics of the ecological environment, extracted the geospatial information of Chongqing downtown along the Jialing River basin, constructed evaluation index system of eco-environmental sensitivity, selected and improved the appropriate single factor, multi-factor evaluation model at the same time. And this paper used the remote sensing images of Chongqing city in 2007, land using maps of Chongqing, administrative maps, soil maps, river maps, digital elevation maps, years of rainfall and other data, and remote sensing, geographic information systems and statistical methods to evaluate environmental sensitivity of Jialing River basin comprehensively. In the evaluation process, the sensitivity of soil erosion, acid rain, comprehensive ecological sensitivity are also be evaluated, and be divided into non-sensitive, light sensitive, moderately sensitive, highly sensitive and extremely sensitive level.In study area, soil erosion has no extremely sensitive areas. Moderately and light sensitivity are the main degree of soil erosion sensitivity. Their areas are 1287km2 and 1113km2, and accounted for 39.40% and 45.56% of total area. These regions are distributed along the Jialing River, south of Shapingba, Beibei, and Northern Yubei. Light sensitivity is the main degree of Acid rain sensitivity, and its area is 1260km2, accounting for 44.21% of the total area, mainly distributed along the Jialing River, north of Yubei, north of Beibei, and south of Shapingba. Moderately sensitivity is the main degree of comprehensive environmental sensitivity, and its area is 1194km2, accounting for 42.27% of total area, mainly distributed along the Jialing River, north of Beibei, Yubei and Shapingba.Thus, the coastal area along the Jialing River is the most sensitive sites of ecological environment, especially in Yuzhong District and Jiangbei District. There have rapidly economic growth and highly urbanization, so they have greater impact on the ecological environment. And most parts of the study area are moderate degree of sensitivity, especially Yubei district. In recent years, the Economic Development Zone and Northern New Zone in YuBei become the key areas of Chongqing development. And Yubei has larger area that accounted for almost 1/2 of the study area, so Yubei have greater impact on the ecological sensitivity of the entire study area.