Retrieving Three‐Dimensional Deformation in Groundwater Pumping Areas Based on InSAR Data

Abstract Monitoring three‐dimensional (3D) surface deformation in groundwater pumping areas remains a significant challenge, as conventional InSAR techniques are constrained by their limited sensitivity to north‐south displacement. This study develops an inversion approach—the Vertical Gradient‐Constrained Strain Model (VG‐SM3D)—that combines multi‐track (ascending and descending) InSAR line‐of‐sight data with a strain model and a physical prior relating horizontal deformation to the vertical deformation gradient. The method is validated using simulated data and applied to the Tianjin region, which experiences substantial subsidence due to groundwater extraction. VG‐SM3D successfully reconstructs the 3D deformation field, revealing pronounced subsidence (peaking at ∼150 mm/yr) and horizontal motion (up to ∼20 mm/yr) that converges toward the centers of subsidence funnels. Comparisons with leveling and GNSS measurements demonstrate good agreement, with estimated uncertainties below 4 and 5 mm/yr for the horizontal and vertical components, respectively. The derived horizontal strain field shows compression within funnel centers and extension along their edges. Furthermore, comparisons with groundwater level data indicate that subsidence is spatially correlated with groundwater drawdown cones, while horizontal deformation aligns well with horizontal hydraulic gradients. This study provides an effective framework for retrieving 3D deformation in pumping zones and offers important insights into the interactions between groundwater extraction, aquifer stress, and surface displacement.