Investigation On Terrestrial Water Storage Changes And Their Connections To Climate Factors Over The Qaidam Basin Based On GRACE Data

Water resources play a very important role in human survival and economy.The rapid development of modern industry and agriculture has exacerbated the contradiction between water supply and demand.The main way to alleviate this contradiction is to understand the terrestrial water storage changes.Thus,the study of terrestrial water storage changes(TWSC)has great significance.The Qaidam Basin is a typical closed mountain basin.The special topography and geomorphology restrict the traditional methods of monitoring water storage changes.Gravity Recovery And Climate Experiment(GRACE)provides a new method for monitoring large scale water storage changes.Compared with the traditional methods,the advantages of this method are obvious.It has achieved huge results in the field of geoscience research.The time-variable gravity field data from GRACE and GRACE Follow-on of RL06 version between April 2002 and December 2019 provided by CSR are used in this study.The methods based on spherical harmonic coefficient(GSH)and Mascon are both adopted to obtain the temporal and spatial distribution of TWSC over the Qaidam Basin.The singular spectrum analysis(SSA)method is used to analyze the time series,and compares with the Global Land Data Assimilation System(GLDAS),precipitation and other data;According to the water balance principle,this study compares the results with GRACE;Correlation analysis of three climatic factors(Arctic Oscillation,Pacific Decade Oscillation,El Ni(?)o and Southern Oscillation)and GRACE interannual and seasonal signals is carried out to analyze the impact of climate factors on the TWSC of the basin.The main contents and conclusions of the study are as follows:(1)From 2002 to 2019,the TWSC in the Qaidam Basin showed an increase trend.The rates obtained by GSH and Mascon were 0.62 cm/yr?0.56 cm/yr,respectively;After SSA analysis,it was found that the interannual signals trend of TWSC is divided into stages: rise-fall-accelerated rise.The two turning points appeared in 2013 and 2015 respectively(Mascon method is 2016);The spatial trend of TWSC in the basin is positive;the overall characteristics are “fast in the south and slow in the north,high in the south and low in the north”;(2)The TWSC obtained by GLDAS also shows an increase trend,with a rate of 0.25 cm/yr.The interannual signal is also divided into three stages: rise-fall-accelerated rise;The seasonal characteristic is that it reaches a peak in summer or autumn and drops to a valley in spring;Before2019,TWSC derived from GSH and Mascon are more consistent with GLDAS;(3)The precipitation and evapotranspiration in the basin show an obviously seasonal characteristics;Precipitation is the dominant factor affecting TWSC in the basin;It is found that climate factors have little influence on the seasonal signals of TWSC in the basin,but have an influence on the interannual signals.Among them,the impact of the Pacific Decade Oscillation has a greater influence on it.