Ground Deformation Monitoring in Beijing-Tianjin-Hebei Metropolitan Region Using Time Series InSAR Method

To accommodate the acceleration and expansion of urbanization, it is necessary to monitor urban geological disasters such as land subsidence. The Beijing-Tianjin-Hebei metropolitan region, as a national strategic supersite in China to promote the innovation of regional development systems and mechanisms, has constantly struck by major disasters. Using satellite images provided by the European Space Agency's Copernicus Sentinel-1 mission, this study applies time-series Interferometric Synthetic Aperture Radar (InSAR) analysis to measure and cross-validate the ground deformation in the Beijing-Tianjin-Hebei region based on ascending and descending orbital results. In Beijing, the eastern part is subject to faster sinking rate than other areas. There are three evident areas with high subsidence rates, and the maximum cumulative sinking rate reaches -60 mm/yr during 2017-2022. The exploitation of groundwater and underground space are the primary drivers for ground deformation in Beijing-Tianjin-Hebei. The land subsidence has been recently mitigated by the replenishment of groundwater from the South-to-North Water Diversion Project. Our study shows that time-series InSAR analysis is an effective tool to assess the hazard exposure in metropolitan areas for an ultimate goal of urban resilience.