Identifying the status of groundwater drought from a GRACE mascon model perspective across China during 2003–2018

The traditional groundwater drought monitoring method relies on the ground observation data, which is difficult to reflect the large-scale groundwater drought information. Thus, Gravity Recovery and Climate Experiment (GRACE) gravity satellite technology is applied to estimate large-scale groundwater drought condition, which can provide a new data source for drought investigation. However, the dynamic variations of GRACE-based groundwater drought were still unclear across China. In this study, the evolutions of groundwater drought were investigated from a high-resolution GRACE mass concentration (mascon) model perspective. The spatio-temporal variations and gridded trend characteristics of groundwater drought were comprehensively identified across China during 2003–2018. Subsequently, the relationships between groundwater and meteorological drought were quantitatively revealed. The results indicated that: (1) the verification results of GRACE were credible and reliable for groundwater drought evaluation; (2) the most serious groundwater drought occurred in April 2011, with an average groundwater drought index (GDI) value of –0.86; (3) the gridded drought trend characteristic showed that groundwater drought presented an upward trend during 2003–2018; and (4) the propagation dynamics from meteorological to groundwater drought were shorter in summer (5–6 months), and longer in winter (14–15 months) across China. This study sheds new viewpoints into groundwater drought variations from a perspective of high-resolution GRACE mascon model, which can also be applied in other areas.