Integrative Assessment On Land Sandy Desertification In Western China Based On Remote Sensing And GIS

In the current time, land sandy desertification is the serious environmental problem which has become the focus of the global. During all kinds of the desertification, sandy desertification is the most serious one. China is one of the countries in the world with most serious sandy desertification. The desertified land widely distributes in the arid, semi-arid and sub-humid areas in western China, especially in crisscross zones of pastures and farmlands, where desertified land expands more rapidly. This is becoming a vital threat to the nation's ecological environment and to the people's living and producing in these areas.In this dissertation, in order to assess land sandy desertification in western China, the author analyzed the basic natural, social and economic features in this area firstly. Through this way, the environmental background of land sandy desertification was specified. On the basis of it, according to the laws, methods and indicators of regionalization, the desertified lands of western China were divided into 2 zones and 7 subzones, which provided the regional basis for the following research. Then, with the remote sensing data, the degree of land sandy desertification was classified and the spatial distributions of land sandy desertification were analyzed. Following the above, according to AHP(analytical hierarchic process) and by means of the most advanced international models of Press-State-Response, the concept frame of integrative assessment on land sandy desertification was creatively built and the concept frame of the assessment indicators were formed. On the basis of the above, the integrative assessment and mapping of land sandy desertification in western China were achieved accordingly. The research results are as follows:1 . It is indicated by the analysis of the spatial distributions of land sandy desertification that the area of it accounts for 55.32% of the total research area. The total area of serious sandy desertification land, violent sandy desertification land, extremely violent sandy desertification land and severe sandy desertification land accounts for 59.98% of the total desertified land. The slight sandy desertification land only accounts for 9.99% of the total. At the same time, the sandy desertification degree defers from region to region. But on the whole, the sandy desertification degree in the arid region is more serious than that in the semi-arid region.2. From the point of integrative assessment, the area of the first-level region, the second-level region, the third-level region, the fourth-level region and the fifth-level region accounts separately 1.75%, 6.28%, 12.43%, 24.73% and 54.81%. On the whole, there are little precipitation, severe human beings' disturbances, low-level systematic vigor and serious soil erosion in western China, which resulting in the high degree of sandy desertification accordingly.