The Analysis Of Desertification Landscape Changes Around Qinghai Lake

The study area in this article is Qinghai lake , a inland lake in Qinghai-Tibet plateau. using remote sensing (RS) and geographic information systems (GIS), through the NDVI, texture analysis, band ratio method, maximum likelihood, spectral angle Mapping (SAM) and other methods, we derive the hierarchical classification of landscape images from the two TM images shot by Landsat in 1987 and 2006. According to the wild investigation in the study area, combined with relevant information and research, established a classification standards of desertification land grading, and in accordance with this standard, the classification of desertified landscape type are present. calculating the area of desertified land form and the matrix of desertified land change. With the method of landscape ecology, analyzing the landscape characteristics and the changes of landscape pattern in the past 20 years from the the level of patch type and landscape level. Meanwhile, discussing the driving factors of desertification in this area,including natural factors, social factors and nature-society factors, we can get the conclusions as follows:(1)the overall characteristics of the regional landscape: the main landscape types in this study is the potential desertified land, lakes and alpine meadows. Among which the area of potential desertified land is the biggest.(2)Desertification is very common around the lake, and the total area of desertified land are 5807.03km~2, accounting for 38.90% of total area in the study region. The potential desertified land is the most, the serious desertified land and intensive desertified land are in the second, and the developing desertified land is at least.(3)The density of desertification land scape patch increased from 1987 to 2006, so the degree of landscape fragmentation became higher, and the analysis of landscape patches represent that the desertification is on progressing.(4)The total area of desertification is decreasing slightly, but the other three types are increasing significantly. The change around the lake is the most obvious. The land becoming the bank when the water level descends is the main transition, and the potential desertification is in the second. So the area of desertification is expending.(5)The desertification in the study region is resulted by the natural factors and social factors. The natural factors are predisposing factors and climate warming and drying is the main driving force. At the same time, population growth and other mankind activities are the fundamental driving factors.