Significant variations in terrestrial water flux in mainland China during 2024 using GRACE-FO: impacts of extreme climate events

Abstract

In 2024, China experiences frequent and severe hydrological extremes, including record-breaking rainfall and widespread droughts, reflecting the intensifying impacts of climate change. The significant changes in terrestrial water storage (TWS) caused by these extreme precipitation events require more detailed analysis to assess short-term hydrological dynamics. Here, we first analyze precipitation anomalies (PA) and percentage of PA (PPA) across mainland China from April to August 2024. The results reveal that PA and PPA in most regions exhibit extreme values in different months, resulting in severe droughts, floods, and abrupt drought-to-flood transitions. To assess the associated water storage changes, we define and apply the terrestrial water flux (TWF), the differenceof GRACE/GRACE-FO-derived TWS anomalies in two adjacent months, as a diagnostic indicator of short-term hydrological variability. Relative to 2002–2024, the grids with TWF percentiles within the 0-10th and 90-100th ranges respectively account for 36.52%, 46.22%, 44.79%, and 46.48% of the total grids from April to August in China. Additionally, 19.89% of grids have the maximum TWF value in 2024. These extremes closely align with variations in precipitation, suggesting that intensified TWF is primarily driven by meteorological factors rather than GRACE-FO data uncertainties. Overall, this study demonstrates the effectiveness of TWF in capturing rapid hydrological changes under climate extremes. The findings provide critical insights into the impacts of climate change on regional hydrological processes and offer a valuable reference for future climate risk management and adaptation strategies at both national and global scales.