Impact of Climate Change on Snowmelt Runoff in the Mountainous Regions of Northwest China
WANG Jian, SHEN Yong ping, LU An xin, WANG Li hong, SHI Zheng tao (Cold and Arid Regions Environmental and Engineering Research Institute, CAS, Lanzhou Gansu 730000, China)
Snow cover is an indicator for global warming. Climate change influences the distribution of glaciers and snow. Thus, air temperature rising results in changing of distribution of seasonal snow cover and regime of snowmelt runoff in Northwest China. Heihe Basin is a typical snow cover region with an area of 10 009 km 2 in Northwest China, where snowmelt runoff is the main supply for water resources. It is found that an impact of climate change on snowmelt runoff in mountainous regions is clear in the basin. So in this paper, the Heihe Basin was sampled to analysis the impact in mountainous regions of Northwest China. The impact of snowmelt runoff was simulated by using Snowmelt Runoff Model——SRM and satellite remote sensing data under air temperature rising. By analyzing the climatic and hydrological data sets derived from 46 observation stations for 40 years(1956—1995), an air temperature rising trend since 1956 is seen, together with a stable precipitation. The annual mean air temperature has increased about 0 7~1 4 ℃. Temperature mainly rises in January and February, but less rises in the spring. Meanwhile, in the test area, variation in rainfall and snowfall has a small effect. When air temperature increasing in winter is the main variation of climate change, snowfall will increase correspondingly. Based on statistics, snowfall increasing due to air temperature rising reaches 7%~10%. Snowmelt runoff regime changes with climate changing temporally and spatially. The curves of different coefficient of discharge show a change of monthly mean discharge contribution from the middle ten days of April to the middle ten days of October. The snowmelt period stretches with the shifted advance 10 days. While the discharge increases, the peak of runoff also advances to May.