Satellite Gravimetry Based Total Water Storage Changes from Global Hydrological Basins

Satellite gravimetry using the GRACE/GRACE-FO missions has transformed our ability to investigate total water storage changes in basin scale. The current study investigates the total water storage changes over global hydrological basins based on GRACE/GRACE-FO data. The total water storage changes in terms of variation in equivalent water heights (EWH) are estimated using GRACE/GRACE-FO release 6 (RL06) of the CSR data centre over the time period between 2002 and 2022. The time series have been decomposed into trends, seasonal components and residuals for a better understanding of the variations. The EWH time series shows seasonal signals over most of the basins. The seasonal variations in EWH are in accordance with the prevailing precipitation regime. The highest amplitude of variations is obtained in the case of Orinoco basin. The lower values of EWH variations are observed in the Lena and Mackenzie River basins. Declining trends of EWH variations have been observed in basins like Brahmaputra and Indus. We observe that the decline in the trends is related to the groundwater depletions over the basins.