Satellite radar reveals hidden water crisis, with groundwater reserves in the northern Henan Plain decreasing by over 12 billion cubic meters in 5 years

The Anyang–Puyang Plain in northern Henan is China’s core grain-producing zone. Long-term agricultural irrigation, industrial water demand and uneven seasonal precipitation have caused severe groundwater overexploitation. Sustained groundwater drawdown triggers irreversible inelastic compaction of deep confined aquifers, resulting in extensive land subsidence that damages infrastructure and permanently reduces aquifer storage capacity. Similar coupled hydro-geological hazards have been documented worldwide, such as California’s Central Valley and Iran’s Rafsanjan Plain. Conventional groundwater storage estimation relying solely on well logs or GRACE satellite gravity cannot separate recoverable elastic water from permanent inelastic water loss. Multi-Temporal InSAR (MT-InSAR) can acquire high-precision surface deformation time series and distinguish elastic and inelastic compaction signals, providing a new way to invert aquifer skeletal storage coefficients. At present, few integrated inversion frameworks combining InSAR deformation and multi-year well water levels have been developed for this study area, which restricts systematic quantitative analysis of groundwater depletion patterns. Based on Sentinel-1A MT-InSAR deformation time series from 2017 to 2022 and long-term in-situ hydraulic head observations, this paper constructs a hydrogeology-coupled inversion system to calculate elastic and inelastic skeletal storage coefficients, quantitatively assess total groundwater storage loss, and reveal the spatiotemporal migration of depletion zones. The results offer quantitative support for groundwater extraction control and aquifer restoration in northern Henan.

The datasets include 66 ascending Sentinel-1A C-band SAR scenes (March 2017–November 2022), 30 m TanDEM-X DEM, multi-year water level records from 85 monitoring wells, and vertical displacement data of 19 CORS stations for result validation. GAMMA and StaMPS/MTI software are adopted for MT-InSAR processing; TOPS co-registration is optimized, and orbital plus atmospheric phase artifacts are removed to extract time-series vertical deformation of stable distributed scatterers. Multi-channel Singular Spectrum Analysis (MSSA) decomposes deformation and water level sequences to separate seasonal elastic components and long-term inelastic trends. Based on preconsolidation head theory, two compaction types are distinguished: when hydraulic head exceeds the preconsolidation threshold, deformation is purely elastic, and elastic storativity is solved by the ratio of seasonal deformation to seasonal head variation; when head drops below the threshold, aquitards undergo irreversible inelastic compaction, and the inelastic skeletal storage coefficient is fitted via Hoffmann’s lag compaction equation. Total groundwater storage change is estimated by integrating deformation over spatial areas. The Standard Deviational Ellipse (SDE) model is applied to characterize annual shifts of depletion centroids and directional patterns. A standardized remote sensing-hydrogeology joint inversion workflow is established, with CORS data used to verify InSAR deformation accuracy.

The results show that time series of InSAR subsidence and well water levels show strong correlation, with the maximum Pearson correlation coefficient reaching 0.993; surface subsidence is dominated by inelastic aquifer compaction. The elastic skeletal storativity ranges from 0.00093 to 0.01596, while inelastic storativity varies between 0.0362 and 0.0457, 5–12 times larger than elastic values, indicating most water loss from over-extraction is permanent. From 2017 to 2022, the cumulative irreversible groundwater loss reaches about 3.01×10⁸ m³, and total groundwater storage depletion is −12.27×10⁹ m³ with an annual average loss of −2.19×10⁹ m³; northern Anyang suffers the most severe depletion. The maximum annual subsidence rate hits −73 mm, with two major subsidence centers in urban Anyang and southern Huaxian; local uplift zones exist where groundwater recharge occurs. SDE analysis demonstrates that groundwater depletion centroids continuously migrate northwestward, the minor axis of ellipses shrinks and the major axis extends, showing intensified spatial clustering aligned along the northwest direction. The study proves the aquifer system undergoes persistent overdraft, elastic regulation capacity declines sharply, and permanent inelastic depletion expands continuously. The derived hydrogeological parameters and spatiotemporal evolution features provide quantitative reference for regional groundwater extraction restriction and artificial recharge planning.

Title:
Spatiotemporal dynamics of groundwater storage inferred from MT-InSAR and hydraulic head data in Anyang–Puyang Plain
Journal Name: Geodesy and Geodynamics
DOI: 10.1016/j.geog.2025.09.004
URL: https://scholarcast.cast.org.cn/top-news/2078006489820557312