3D surface displacement modeling in Lorca, Spain, using dual-orbit MT-InSAR and multiple prior constraints

Excessive groundwater pumping is a significant driver of land deformation, potentially threatening regional geological stability. Interferometric synthetic aperture radar (InSAR) has been widely used to monitor such deformation. However, existing studies primarily focus on retrieving InSAR line-of-sight (LOS) or ground vertical deformation, limiting insights into three-dimensional (3D) ground displacements driven by subsurface processes. To address this, we propose a novel approach for modeling 3D surface displacement by integrating dual-orbit Multi-Temporal InSAR measurements with multiple prior deformation models. Specifically, we first estimate two sets of 3D displacements using a Bayesian approach by integrating dual-orbit InSAR measurements into prior models. Subsequently, bidirectional matching is employed to identify reliable homologous points, which are then used to reconstruct the complete horizontal displacement fields through the surface horizontal force equilibrium equation. Following the proposed methodology, for multi-track and high-coherence data, minimum acceleration (MinA) combination, multiple-aperture interferometry (MAI), and burst-overlap interferometry (BOI) techniques can serve as alternatives to conventional approaches. Moreover, incorporating along-track motion will further enhance 3D deformation estimation using SAR data. In the Lorca basin, Spain, we utilized Sentinel-1A ascending and descending SAR images to construct high-precision 3D cumulative displacement fields between October 7, 2015, to March 24, 2017. The experimental results reveal a maximum cumulative subsidence of 121.5 mm and notable horizontal displacements with a peak magnitude of 18.6 mm, a component that has received limited attention in earlier studies. The proposed approach eliminates the need for ground-based observations and yields improvements of 33.7 %, 51.3 %, and 43.9 % in the accuracy of vertical, east–west, and north–south deformation components, respectively, compared to the SMVCE method that integrates both InSAR and GNSS data. This study addresses the low sensitivity of InSAR in monitoring north–south displacement induced by groundwater extraction, offering new evidence to elucidate deformation mechanisms and providing valuable implications for sustainable groundwater management and geohazard mitigation.