Monitoring spatio-temporal changes of terrestrial water storage in Guangdong province based on satellite gravity and analysis of driving factors

Water resource is the core element for maintaining ecosystems and economic development． In recent years, China has actively carried out fundamental surveys of water resources to collect baseline hydrological data for regional water management． In this context, this study integrates GRACE/GRACE-FO, GLDAS and measured groundwater data to investigate spatio-temporal changes in terrestrial water storage (TWSA), surface water storage (SWSA), and groundwater storage (GWSA) in Guangdong province from April 2002 to December 2024． This study analyzes driving factors for changes in regional water storage using precipitation, temperature, potential evapotranspiration, and water consumption data． In Guangdong province, TWSA shows surpluses in eastern and northern regions, with an overall rate of change at (0.19±0.09) cm·a⁻¹ and a consistency of 72.4% in relative change rates compared to water resource bulletin data． GWSA saving function in central and western regions was limited by exploitation, and correlation coefficient between GWSA and measured groundwater changes reached 0.73． Driver analysis revealed that changes in terrestrial water storage correlated with meteorological factors in descending order of correlation strength: precipitation, potential evapotranspiration, and temperature, but exhibiting a negative correlation with water consumption． Regarding extreme drought and flood events monitoring, drought index GRACE-DSI and standardized precipitation index (SPI) reach 51.9% and 62.5% agreements respectively for identifying regional drought and flood events, and effectively reflected types of wet and dry years recorded in the water resource bulletin． These findings provide large-scale data references for fundamental surveys of water resources in Guangdong province．