STUDY OF CHANGES OF VEGETATION AND SNOW AREA IN QILIAN MOUNTAINS USING METEOROLOGY SATELLITE DATA

The characters of vegetation spatial distribution and changes in Qilian Mountains are analyzed using NOAA meteorology satellite data in 1989 and 1998. The changing features of snow area in Qilian Mountains are studied using the same data. The results show that the vegetation of the main body of the mountain is degenerating and the major degenerating vegetation are shrubbery and grass. The basic annual changing characteristic for the snow area is double peak style, but there are differences in the changes of the snow area among each river valley. The ten-day averaged snow area in 1998 is lesser than that in 1989. The decrease extent of the snow area is gradually increased from west to east. The snow area decreased 2.17% in Danghe valley (in the west of the mountains) and 10.05% in Xiyinghe valley (in the east of the mountains). The changing features of snow area in 1998 was similar to in 1989 in spring and the snow area in 1998 was obvious lesser than in 1989 in winter. Because the temperature in 1998 is much higher in 1989, the velocity of snow melting in 1998 is faster than in 1989.