The Impact of Climate Changes on the Cold Region Hydrology at the Northern Slopes of the Qilian Mountains
Yang Zhenniang, Wang Qiang and Zhu Shousen(Lanzhou Institute of Glaciology and Geocryohgy. Chinese Academy of Sciences, 730000)
The water resources of the Hexi area originated from the Qilian Mountains, which are covered with glaciers and permafrost. Streams of the eastern Qilian Mountains are mainly supplied by precipitation, and in the western are supplied by ice-snow melt water. The stream runoff has been decreasing in the eastern and mid sections of the Qilian Mountains since 1950s to 1990s; and the stream runoff is less than the mean runoff during 1950s to 1960s, then during 1970s to 1990s, the runoff changes are in the opposite in the western Qilian Mountains.Base on the variation period, runoff formation, the statistical analysis method is used to predict the stream runoff. It shows that the warm climate period would occur in 2020, and the stream runoff would decrease by 30% and 50% for the precipitation feeding type of streams, when the precipitation decreases by about 25% and 50% respectively. And the stream runoff would increase by 40%-70% for the type of ice-snow melt feeding streams, when the air temperature rises by 2.5℃ and 3.5℃ respectively.