Driving factors and changes in components of terrestrial water storage in the endorheic Tibetan Plateau

Terrestrial water storage (TWS) in the endorheic Tibetan Plateau (ETP) increased from 2002 to 2012 but decreased in 2012–2016. This study used Gravity Recovery and Climate Experiment (GRACE) data and Global Land Data Assimilation System (GLDAS) data to analyse TWS changes in the ETP in 2012 from increasing to decreasing. The results showed that these TWS changes could be divided into two stages. From April 2002 to August 2012, TWS increased at a rate of 4.43 Gt/yr from the GRACE-Mascons and 1.11 Gt/yr from the GRACE-SH, whereas after September 2012, it declined at a rate of-5.62 Gt/yr from the GRACE-Mascons and −6.99 Gt/yr from the GRACE-SH. The increase in lake water storage (LWS) (7.98 Gt/yr) was higher than the loss of other components from 2002 to 2012, therefore, the LWS gradually dominated the increase in TWS. However, the soil moisture storage (SMS) decreased more significantly (-5.27 Gt/yr) than the increase in LWS (<1 Gt/yr) during 2012–2016, accounting for 66% of the decrease in TWS in the ETP. From a water balance perspective, the relationship between precipitation (P) and evapotranspiration determined the region’s changes in TWS. It was found that 90% of the decrease in TWS in the ETP during 2012–2016 was attributed to an increase in potential evapotranspiration (PET), whereas 7% was attributed to a decrease in P. Thus, climate change (P and PET) accounted for 97% of the TWS reduction during 2012–2016. Furthermore, 3% of the decrease in TWS in the region was attributed to land surface changes.