Analysis of recent land usage and survey in Western China
中国西部地区土地利用/土地覆盖近期动态分析

From 1995 to 2000, field data collections using Remote Sensing(RS) and Geographic Information System (GIS) have been conducted in 12 provinces of China' western regions. The land usage and 6 types of vegetation coverage show an average accuracy of 92.92%. Dynamic patches of the land usages and vegetation coverage types of the western provinces are analyzed. A total of 138746 of dynamic patches are obtained; and contains all major vegetation coverage types. The average reliability reaches as high as 97.71% for the classification on the dynamic land usage types and 99.85% for the demarcation of patch boundaries. The investigation shows that (1)cultivated land has increased by 1206500 hectares in recent 5years,i.e., 2.41% larger than that in 1995;(2)The forested and grass areas have decreased by 615000 and 1196500 hectares, 0.61% and 0.59% less than that in 1995, respectively;(3)The urban and wetland areas have increased by 192500 and (4)The environmental issues on desertification and salification in Western China have worsen. Unusable area has been increased by 242800 hectares in these regions due to droughts, oil explorations and other human activities, in which the desertification area occupies 26.94%.