Multi-temporal SBAS-InSAR monitoring of urban ground deformation in Riyadh, Saudi Arabia

Riyadh, Saudi Arabia, is undergoing rapid urban transformation driven by large-scale infrastructure development projects. Recently, Riyadh Metro project is considered one of the cutting-edge technologies that aims to decrease the overwhelming road congestion. However, the general ground deformation caused by tunneling and excavation activities may cause a serious threat to the infrastructures. This study investigates ground deformation associated with the Riyadh Metro constructions over a six-years period (2017–2023) using advanced remote sensing techniques. Interferometric Synthetic Aperture Radar (InSAR) analysis was implemented through the Small Baseline Subset (SBAS) approach to derive high-resolution deformation measurements. A total of 252 Sentinel-1 SAR scenes from the ascending orbit were processed, generating 126 interferograms from the IW mode, with analysis focused on the F2 subswath covering the metropolitan area of Riyadh. Line-of-sight (LOS) velocity fields and deformation time-series were produced to quantify spatial and temporal patterns of ground movement. Validation was conducted using observations from the SAS0 GNSS station for the period (2019–2021) demonstrating strong agreement between satellite-derived and ground-based measurements. The results reveal localized subsidence exceeding 6 cm/year in major construction zones, particularly near metro line intersections, tunneling corridors, and deep excavation sites. Temporal analysis indicates a pronounced acceleration of subsidence in early 2020, interpreted as a delayed geotechnical response to intensive excavation and loading activities during 2019. These findings confirm the robustness and reliability of the SBAS-InSAR techniques for long-term urban deformation monitoring. Furthermore, the study underscore the critical importance of continuous geodetic surveillance in mitigating geotechnical risks, safeguarding adjacent infrastructures and supporting sustainable urban development during and after megaprojects such as the Riyadh Metro.