Land use and economic development influenced the hotspots of groundwater storage gains and losses in mainland China in the past 20 years

Groundwater is the world’s largest freshwater resource after ice caps and glaciers, and its over-exploitation can disrupt regional hydrological cycles, leading to issues such as land subsidence and salinization. Identifying hotspots and drivers of groundwater storage changes is essential for sustainable water management and climate change mitigation. This study uses GRACE/GRACE-FO satellite data to identify groundwater storage change hotspots in mainland China over the past two decades, employing Pettitt-test and temporal stability analyses. To ensure reliability, we cross-validated the GRACE/GRACE-FO-derived groundwater storage against Watergap Global Hydrological Model and available well records, the correlation coefficient distribution is 0.76–0.88. The hotspots are categorized into loss (I, II, III) and gain (IV, V) categories. The severity of both gain and loss conditions increases with the level. Additionally, the study quantifies the contributions of natural and anthropogenic factors by integrating climatic and socio-economic variables. The results indicate that loss hotspots dominate in North China, Loess Plateau, Northwest China, Northeast China, and Qinghai-Tibet Plateau. In the Qinghai-Tibet Plateau region, the combined proportion of Level I, II, and III loss hotspots exceeds 60%, whereas in other regions, the combined proportion of these loss hotspots is over 75%. In contrast, surplus hotspots are prevalent in South China, Ch-Yu region, Middle-Lower Yangtze River, and Yun-Gui Plateau, where level IV and V gain hotspots exceed 60%. Groundwater changes in the Qinghai-Tibet Plateau and Loess Plateau are primarily influenced by land use, whereas economic factors play a more significant role in other regions. This study offers valuable insights into regional groundwater changes across China and provides a scientific foundation for effective water resource management.