Spatiotemporal evolution and attribution analysis of groundwater drought in the North China Plain: GGDI constructed based on downscaled GRACE GWSA

North China Plain (NCP), China. To address the limitations of low-resolution data accuracy and insufficient quantitative characterization of driving mechanisms in groundwater drought assessment in the NCP, this study proposes a systematic research framework: downscaling GRACE data using Geographically Weighted Regression (GWR) to reconstruct 0.05° Groundwater Storage Anomalies (GWSA) for 2002–2023 and construct the GRACE Groundwater Drought Index (GGDI). Furthermore, combining Random Forest (RF) with Geographic Detector (GD) reveals the quantitative contributions of natural and anthropogenic factors and their interactions (2003–2022). This framework overcomes the limitations of traditional research in spatiotemporal resolution and mechanistic interpretation, providing a new methodological approach for regional groundwater drought research. (1) From 2002–2023, the 0.05° GWSA exhibited higher accuracy than the 0.25°, revealing a −17.81 ± 3.31 mm/yr decline. (2) Drought was mild in the northeast and severe in the southwest. The 0.05° GWSA first detected relief in approximately 4 % of the region (e.g., northern Beijing and northwestern Cangzhou). Fifteen drought events were identified during the study period, showing increasing frequency and intensity. The GGDI rebounded in 2016 and 2021 due to rainfall, the South-to-North Water Diversion, and groundwater-withdrawal restrictions. (3) Groundwater extraction was the dominant driver (contributing 45 %), and its interaction with precipitation markedly amplified drought risk (q = 0.83), particularly in fine-grained aquifer areas. • Proposing a downscaling groundwater drought identification framework. • Quantifies driver-response mechanisms of drought by natural and human factors. • 0.05° reveals spatial groundwater drought details obscured at 0.25° resolution. • Groundwater drought in about 4 % of the region has been alleviated. • The synergy of groundwater extraction and precipitation intensifies drought risk.