Variations and drivers of terrestrial water storage in ten basins of China

Study region: Ten major river basins in China.Study focus: The spatial and temporal distribution of terrestrial water storage (TWS) in China is significantly affected by global climate change and increased human activity. In this study, we analyzed the spatial and temporal variability of TWS in ten Chinese basins based on data of the Gravity Recovery and Climate Experiment (GRACE). To discuss the driving force of TWS, we assessed the relative contributions and time lags of precipitation (P), evapotranspiration (ET), and runoff (R) to TWS using Spearman correlation analysis and partial least squares regression (PLS). New hydrological insights for the region: Results indicate that: (1) TWS generally shows a reduction trend at a rate of 1.58 +/- 0.067 mm/a from 2003 to 2020, with the most significant decreasing trend in September (-2.77 +/- 0.070 mm/a). (2) The relative contributions of P, ET, and R to the TWS in China are 29.89 +/- 6.98%, 31.03 +/- 6.92% and 39.09 +/- 10.82%, respectively, and are more prominent in low-latitude regions than in high-latitude regions. (3) The best-correlated lag times were 1-2 months between the P and TWS responses. (4) Melting snow, ice and groundwater extraction may have weakened the response of the northern TWS to the climate. The results provide insight into the spatial and temporal variation in water storage, which can provide a basis for the scientific and effective management of water resources.