Spatiotemporal dynamics of groundwater storage inferred from MT-InSAR and hydraulic head data in Anyang–Puyang Plain

Groundwater overexploitation in northern Henan Province has led to significant land subsidence and aquifer degradation. This methodologically driven study proposes a physically consistent framework that integrates Sentinel-1A-based Multi-Temporal Interferometric Synthetic Aperture Radar (MT-InSAR) data (2017–2022) with long-term groundwater head observations to invert elastic and inelastic skeletal storage coefficients and assess total groundwater storage (TGWS) changes. The framework is applied to the Anyang–Puyang Plain as a representative case study. MT-InSAR deformation time series were combined with Multi-channel Singular Spectrum Analysis (MSSA) decomposition and polynomial fitting to extract seasonal and long-term trends, enabling spatially distributed inversion of aquifer parameters. Results show strong spatial coupling between land subsidence and hydraulic head decline (maximum Pearson r is 0.993), with deformation dominated by inelastic compaction. The elastic storativity ranges from 0.00093 to 0.01596, whereas the inelastic storativity, ranging from 0.0362 to 0.0457 indicates irreversible compaction processes associated with a cumulative groundwater loss of approximately 3.01 × 10⁸ m³. Based on the long-term groundwater level observations collected in this study and the inferred assumption of preconsolidation head, the TGWS loss reached −12.27 × 10⁹ m³, with a mean annual rate of −2.19 × 10⁹ m³/yr and pronounced depletion in northern areas. Standard deviational ellipse (SDE) analysis revealed a north-westward shift of the depletion centre and enhanced spatial clustering. These findings provide critical hydromechanical insights and quantitative constraints for future groundwater regulation and aquifer recovery strategies in overdrawn regions.