Study On The Vulnerability Of Ecological Environment In The Upper Reaches Of Jialing River Basin

With the increasing attention of the whole society to the living environment of people,the concepts of ecological civilization construction,sustainable development and human land coordination have gradually entered our vision.Facing the increasingly conflicting human land contradiction,the increasingly scarce natural resources,and the accelerating urban expansion,the ecological environment problems need to be solved.The quantitative evaluation of ecological environment vulnerability and the accurate identification of ecological environment vulnerable areas are very important.The upper reache of Jialing River is the interlaced belt in the South and north of China,the transition zone of first and second steps,the important sub basins of the Yangtze River,the junction zone of Sichuan,Shaanxi and Gansu provinces,which is the ecological security barrier of the Yangtze River economic belt,the reserve of economic construction in the western region,the bottom line of ensuring the living environment safety and the rear of maintaining species resource abundance.The melting of ice and snow,the advance and retreat of loess and the turbid water source all indicate global climate change.This paper selected 22 indicators which can reflect the natural and social aspects of the upper reaches of Jialing River Basin.The ecological environment special evaluation of the research area in 2000 and 2015 was carried out by using principal component analysis and different index combination methods.The evaluation projects include three aspects: ecological environment sensitivity,ecological environment restoration and ecological environment stress.Based on the result of special evaluation,In this paper,the entropy weight method is used to determine the corresponding weight coefficient,and then constructs a comprehensive evaluation model of ecological environment vulnerability.Finally,according to the spatial and temporal characteristics of the vulnerability index of the ecological environment in this area,and combining the characteristics of regional geographical elements,the vulnerability of the ecological environment is divided into three parts.The main conclusions are as follows:(1)The spatial distribution pattern of ecological environment vulnerability in 2000 and 2015 is basically the same.generally,the vulnerability index of the ecological environment in this area reduced from 0.22 to 0.21,77% of the areas with the decrease and 23% increase of the index were respectively.The overall development trend of ecological environment in the research area is good.(2)This paper divides into five areas the fragile ecological environment area of loess hills in South Gansu,the fragile zone of ecological environment in Huicheng basin,the fragile zone of Mianli fault Jialing River ecological environment,the main stream ecological environment vulnerability zone of Bailong River Basin,the ecological environment vulnerable areas in the northern section of Longmenshan mountain,and the transition ecological environment stability area between the mountain and loess hills The five ecological environment stability areas represented by Ruoergai Plateau mind I mountain system ecological environment stability area,Bailong River Baishui River watershed ecological environment stability area,Jiuzhaigou high altitude ecological environment stability area and West Qinling ecological environment stability area are representative areas;the north and South Qinling ecological environment excellent areas,the Ferris mountains ecological environment excellent area and Micang mountain ecological environment excellent area 3 ecological environment excellent areas.(3)By considering the correlation between the fragility of the ecological environment and the differentiation of geographical elements,the first laws of geography are confirmed in the heterogeneity distribution of regional ecological environment vulnerability.The factors that cause the vulnerability of the ecological environment in the upper reaches of Jialing River Basin are summarized as geomorphic factors,altitude factors,fault factors and population factors.The four factors are related to each other,which together create the spatial distribution characteristics of the vulnerability of the ecological environment in the study area.(4)In order to better support the ecological governance and assist the development of river length system,77 small basins in the study area are used as evaluation units to evaluate the ecological environment vulnerability of each small watershed.The results show that the rivers with high ecological environment vulnerability mainly develop in loess hilly areas,while those with low ecological environment vulnerability mainly concentrated in the vicinity of Jiuzhaigou County in 2000,while in 2015,they became Qinling Mountains near Fengxian County.According to the statistical results,the ecological environment vulnerability index of Yanguan River,Yangshui River,maoshui River,Taishi River,Beiyu River,Gou Ba River and Gongjia river is higher.(5)Through the analysis of the driving factors which cause the change of the vulnerability of the ecological environment in this area,the research finds that the surface vegetation type is the most important factor affecting the vulnerability of the ecological environment,while other main driving factors are: land use type,vegetation index,road density,valley density and population density.To improve the vulnerability of regional ecological environment,we can start with the following aspects: increasing the surface vegetation coverage,planting plants suitable for the natural conditions of the region,reducing the impact of human activities on the ecosystem,reducing the rate of reclamation of steep slopes in the region.