Study On The Variation Of Terrestrial Water Storage In The Qaidam Basin Based On GRACE Data

The terrestrial water storage(TWS)is a comprehensive reflection of regional precipitation,run-off,evaporation,groundwater,mankind's development and utilization,and other related activities.It is an important part of the global water cycle observation on the ground.The study of TWS and its changes on regional scale or watershed scale plays an important role in understanding and identifying the status of water resource,climate change,agricultural production,droughts and other natural disasters.Since the implementation of the Gravity Recovery and Climate Experiment(GRACE),studies on the variation of TWS,sea-level and ice sheet have been carried out using GRACE data by the scholars both at home and abroad.For the Qaidam Basin,water cycle on the surface of earth is the main factor that influence the time-variable gravity field of the earth.The residual signal is the variation of TWS after removing the effects of human activity and mass changes in the atmosphere and ocean tides.In this paper,we break through limits of traditional monitoring methods.Data of GRACE RL05,water resources development and utilization,mineral resources development and hydrometeorology are applied to study spatial and temporal variation of TWS and their causes in the Qaidam Basin.Regional time-variable gravity field of the Qaidam Basin is affected more or less in areas with a lot of human activity.We take this part of the disturbance into consideration when calculating the variation of TWS.The ascending velocity of TWS is about 0.26 mm per month during 2003~2015.TWS shows the property of periodicity with the season,it reaches the highest level in winter and the lowest level in summer.The maximum value of TWS appeared in August 2012,In spatial variation,TWS in each region of the Qaidam Basin has increased in varying degrees,the variation of TWS in spatial is quite notable.The multi-year average increment of TWS is gradually increased from the northwest to the southeast.water resource has undergone a process of redistribution,a lot of ice and snow melting water in the high elevation mountainous area flows into low-lying areas in the middle basin.In this process,the water exchange happens between Surface water and ground water.The Qaidam Basin is the most apparent area with increased TWS in the Tibetan Plateau and the variation of TWS accords with the integral change in the north of Tibetan plateau.Increasing precipitation is an important driving factor for the rise of TWS in the study area.In addition,the variation of TWS is also under the influence of terrain topography,vegetation coverage and the change of actual evapotranspiration caused by seasonally frozen soil.The method that we calculate the variation of TWS based on GRACE provides a new way to the water resources assessment in data scarce region in the northwest of China.