Temporal and spatial variation of groundwater storage and drought monitoring in the Tibetan Plateau based on GRACE

With global warming, it is of great significance to understand the changes of groundwater storage in the Tibetan Plateau for water resources management and utilization. Based on the GRACE gravity satellite data, this paper studies the changes of groundwater storage in the Tibetan Plateau from April 2002 to August 2022, and conducts drought monitoring. The results show that the average groundwater storage on the Tibetan Plateau have increased slightly in the past 20 years, with an average increase rate of 0.33 mm/a. In terms of space, the variation trend of groundwater storage mainly shows that the Western Qaidam basin and the Northern Tibetan Plateau increase, and the other regions decrease. When the interannual rainfall in the Tibetan Plateau decreases or increases rapidly, the groundwater reserves will decrease in one year or increase in the next year. There are obvious regional differences in the spatial and temporal variation pattern of the Tibetan Plateau during the year. The northern part of the Tibetan Plateau is mainly affected by rainfall, and the increase intensity and extent gradually increase with the increase of summer and autumn rainfall, and from west to east, the change of groundwater reserves responds to precipitation for a longer time. In the southern Tibetan Plateau, groundwater reserves decreased in summer and autumn and increased in winter and spring. WSDI can effectively monitor drought events on the Tibetan Plateau, which are mainly distributed in the north, northeast and southeast regions of the plateau.