Study on Water Storage Change and Its Consideration in Water Balance in the Mountain Regions over Arid Northwest China
Changes in permafrost and glaciers influence water balance in mountain regions of arid northwest China. Terrestrial water storage change (TWSC) is an important factor in the water cycle. In this study, we used Gravity Recovery and Climate Experiment (GRACE) satellites data to retrieve the TWSC in Tien Shan and Qi Lian Mountains. Variation of seasonal TWSC was obvious. However, the seasonal and annual differences reflected the imbalance of water resource distribution in two mountains. The TWSC decreased in the Tien Shan Mountains but increased in the Qi Lian Mountains during 2003 to 2010. Permafrost and glaciers play an important role in the water cycle in arid mountain regions. Demands for water for agriculture need more groundwater extraction for irrigation and glacial melt feeding the rivers which leads to the state of loss of TWSC in Tien Shan Mountains. Increase and thickening of the active layer of permafrost could lead to more infiltration of surface water into the groundwater, which result in increasing water storage and changes in the regional water balance. According to water balance, precipitation and evaporation changed little in short time, and TWSC changed obviously, whereas runoff showed an increasing trend in the Tien Shan Mountains and a decreasing trend in the Qi Lian Mountains.