Study On The Ecological Vulnerability In Shiyang River Basin Based On RS And GIS Approach

Eco-environment is the basic conditions of human's survival and development. And it is also the foundation of economy and social's development. The rapid increment of the population and the unreasonable exploitation of resources make ecosystem's coordination ability descend continuously, and the living environment of mankind becomes more and more vulnerable. Eco-environment vulnerability problems are major issues of the global change and sustainable development that is studied. Arid region is the sensitive and fragile area and also the area of more serious land degradation. It is more significant to studying the eco-environmental vulnerability and the feature of spatial differentiation in this area. With this guide, human being could use correctly natural resources, protect the eco-environment by the right way and make the sustainable development of economy and society.In this paper, the study area is Shiyang River basin which is a typical inland river basin of the north-west arid areas. Using 4 remote-sensing images, the terrain data,the metrological data and other geography aid-information, distributed map of space index factors whose grid size was 100m×100m was obtained by computed. And raster images were integrated in the same space framework. Data of the evaluation factors were standardized according to the data processing function of RS approach. Evaluation model of Principal component analysis which is about the superposition of multi-source spatial grid data is built in this thesis at the support of GIS approach. The ecological vulnerability in Shiyang River Basin were evaluated by the model. On the basis of which, the grades of vulnerability was classified. Finally, the paper analyzed the discipline of Eco-environmental vulnerability spatial differentiation and the causes. The achievement will provide scientific references for evaluating correctly the development processing, improving the ecological conditions of all the county, providing decision-making about sustainable use and protecting eco-environment in?Shiyang River Basin. The results showed as follow:(1)According to the studying in the domestic, the basin's geographical condition, the characteristic and changeable discipline of Eco-environmental vulnerability and the size of Eco- environmental vulnerability, The grades of ecological vulnerability in the basin was classified into five levels. Through which, ecological vulnerability of the situation in Shiyang River Basin was evaluated. The results showed that: Average value of ecological vulnerable index was 0.6158 and the basin belonged to the strong moderate vulnerability. The level of faint,light,moderate,serious,quite serious vulnerable area was 1520.20,13616.25,8783.14,13473.48,4206.92km2, and they accounted the total areas for 3.65%,32.73%,21.11%,32.39%,10.11%.(2)On the basis of this paper's classification standard, 96.35% of the area was different levels of vulnerability in Shiyang River Basin. Most areas of the northern desert region were serious or quite serious vulnerability; Ecological environment in central belonged to the moderate vulnerability; Ecological environment along the Qilian Mountains in southern part was light or faint vulnerability. Changing trends of ecological vulnerability basically showed that: the vulnerability from the plains to the mountains was gradually lower and plain areas were most serious vulnerability, low hilly regions were moderate vulnerability and mountain regions were faint vulnerability.(3)The ecological vulnerability of seven counties in Shiyang River Basin were valuated by ecological vulnerable model which was built in this thesis. The result showed that there were significant differences among the county. Average value of ecological vulnerability was between 0.4817 and 0.7398.The most severity was 0.7398 and the lest severity was 0.4818.The most vulnerable counties were Jinchang and Minqin which dominated by serious or quite serious vulnerability. Ecological environment had been severely damaged, of which the stability was poor. Ecological environment in Tianzhu was relatively good in the upper reaches of Shiyanghe River Basin. The weakest vulnerable counties was Tianzhu which dominated by faint or light vulnerability. The faint areas accounted the county's total areas for 22.40% where the light areas accounted the county's total areas for 74.62﹪.Sunan,Gulang and Wuwei which dominated by light or moderate vulnerability were conditions of light vulnerability. Eco-environment of Yongchang was serious vulnerability which dominated by serious or moderate vulnerability. Ecological environment of all the counties in Shiyanghe River Basin was so terrible. We should pay close attention to eco-environment in the basin and implement watershed management as soon as possible.