西藏自治区土壤风力侵蚀与沙地变化研究

Study on Wind Erosion and Changes of Sandy Land in Tibet

根据遥感调查的土壤风力侵蚀数据和用主成份分析法得出的土壤风力侵蚀动力指数,对西藏自治区土壤风蚀进行宏观分析。根据中国资源环境数据库中近10年来遥感调查的土地利用时空变化数据,对西藏沙地变化进行空间分析,发现沙地总体上没有明显扩展,处于缩小的过程。沙地主要变化为人工林地,表明了人为因素对沙地的减少做出重要贡献。将地貌数据与沙地的空间分布数据进行叠加,发现西藏的沙地主要分为3种类型:湖积平原型、洪积平原型和河流谷地型。每种类型有着较为独特的沙地成因、分布格局和变化方式,成为西藏风力侵蚀的特点。70年代以来的沙漠化气候因子值偏小,表明了气候因素所导致的土地沙化趋势在减弱。

Based on the data of soil wind erosion intensity and the soil wind erosion dynamic index, the spatial analysis of soil wind erosion of Tibet is carried out. Using landsatTM images, the land use changes from 1990 to 2000 are studied. The result shows there is no obvious expansion of sandy land. The sandy land is shrinking, as is reflected with the expansion of forest. Human activities such planting the trees dedicate to the reduction of sandy land. To the geomorphological analysis of the wind erosion caused sandy desertification in Tibet, three kinds of process exist corresponding to three typical areas that have varied driving factors and different spatial distribution. Using the meteorological data, the climatic factor of sandy desertification is calculated and its spatialtemporal change is analyzed. The result shows that the northwest part of Tibet experiences more intensified wind erosion. From about 1970s to 1990s, the value of climatic factor in most part of the Tibet is decreasing sharply.