Spatio-temporal Variation Of Terrestrial Water Storage In Typical Lake Basins In Central Asia

Central Asia is seriously short of water resources and Lakes are the main support for the ecological environment.In recent decades,affected by the impacts of climate change and human activities,the relationship between inland river basins and water balance in Central Asia has changed,and the contradiction between water resources,ecological environment and social and economic development has become increasingly prominent,which has attracted extensive attention from the international community.However,Terrestrial Water Storage(TWS),one of the important parameters of land water variation,can provide scientific basis for the sustainable utilization of water resources in Central Asia by analyzing its variation trend and influencing factors.In the paper,the Aral Sea Basin,Balkhash Lake Basin and Issyk-Kul Basin in Central Asia were selected as the study areas,and RL06 M and RL05 data products of GRACE gravity satellite from 2002 to2016 were used as data sources,based on the Gl DAS-NOAH hydrological system data?CRU TS4.04 meteorological data? GLDAS-Noah surface evapotranspiration data and high precision land use data,we analyzed the time series trend changes of TWSC?precipitation?temperature and water evaporation by the way of linear trend method.Quantitative analysis of the correlation between TWSC and precipitation?land surface temperature?evapotranspiration and other factors,.thus exploring the effects of climate change and human activities on TWS in typical lake basins of Central Asia.The relevant elements and conclusions are summarized as follows:(1)From 2002 to 2016,the TWS of three typical lake basins showed a decreasing trend.The Aral Sea basin suffered the most severe loss of TWSC.The descending rates of RL06M-JPL?RL06M-CSR?RL05-CSR?RL05-GFZ?RL05-JPL in the Aral Sea Basin were-3.20mm/a?-4.89mm/a?-6.72mm/a?-4.85mm/aand-6.52mm/a;the descending rates in the Balkash Lake Basin were-0.56mm/a?-5.06mm/a?-1.13mm/a?-0.06mm/a?-0.23mm/a;the descending rates in the Issyk-Kul Basin were-2.26mm/a?-7.69mm/a?-5.31mm/a?-4.36mm/a?-4.70mm/a.The seasonal variation trend of TWS in the three basins is consistent: the changes of TWS in the three basins reach the maximum surplus in spring(3 to 5 months)and the maximum loss in autumn(9 to 12 months).(2)The spatial variation characteristics of TWSC extracted from the five GRACE data products are basically consistent,but there are differences between the data products of RL06 M and RL05.The spatial variation of RL06M-JPL and RL06M-CSR showed that the northern part of Balkhash Lake and the central part of Aral Sea Basin had the largest surplus of TWS.The largest losses in TWS are in the eastern part of the Lake Balkhash basin and the northern part of the Aral Sea basin.The results of three sets of RL05 data inversion are consistent,and the maximum surplus is in the north of Balkash Lake Basin.The largest loss occurred in the western part of the Aral Basin.In the inversion results of RL06M-JPL,the TWS of Issyk-Kul Basin showed surplus 0–13.03 mm,while the TWS of other data products decreased by-13.40–-7.70mm?-10.59–0mm?-7.94–0mm?-8.32–0mm.(3)Three basins groundwater storage are declining in time series,the Aral Sea Basin decreases at the rate of-2.26 mm/a and-4.13 mm/a for RL06M-JPL and RL06M-CSR data products;the rate of decrease in Balkhash Lake Basin was-1.74 mm/a and-3.36 mm/a respectively,Issyk-Kul Basin decreased significantly greater than the first two Lake Basin,the decrease rates were-10.25mm/a and-15.72mm/a.The surplus of groundwater storage reaches its maximum in summer(6 to 8 months).RL06-JPL derived groundwater storage increased significantly in the irrigated areas near the middle of the Aral Sea Basin,followed by the eastern part of the Syr River Basin? the southern part of the Amu River Basin and the northwestern part of the Balkhash Lake Basin.In the eastern part of Balkash Lake Basin,the most obvious rate of groundwater storage decline is-31.87–-20.6mm/a.In the inversion results of RL06M-CSR,the largest surplus area of groundwater reserves is concentrated in the central and southern part of the Amu River Basin.The largest losses were concentrated in scattered areas in the east of the Balkhash Lake Basin.(4)The northwest part of the Lake Balkhash Basin as a dissipation area for water resources.With the increase of precipitation and the decrease of temperature,the small increase of evapotranspiration resulted in the decrease of TWS in the northwest of the Balkhash Lake Bsain,the increase of irrigation water and the high level of the southeast of the Balkhash Lake Bsain and the low topography of the northwest leads to a surplus of groundwater storage in the northwest.As an alpine closed lake,Issyk-Kul Basin is less affected by human activities.The significant decrease of precipitation is the main reasons for the decrease of TWS in the Issyk-Kul Basin.The main reason for the surplus of TWS and groundwater storage in the middle part of the Aral Sea Basin is the increase of irrigation-based water storage due to the increase of cultivated land area,the decrease of water area and the increase of evapotranspiration are the main reasons for the decrease of TWS and groundwater in the whole Aral Sea Basin..