MONITORING TIANJIN LAND SUBSIDENCE BY SBAS-INSAR BASED ON SENTINEL-1A SAR IMAGES
In order to understand the spatial-temporal evolution of land subsidence in Tianjin, in this study, we applied the Small Baseline Subset Interferometric Synthetic Aperture Radar (SBAS-InSAR) technique to process 36 Sentinel-1A images acquired between 2015 and 2018 released by European Space Agency (ESA). The results show that during the study period, most of the regional land subsidence rate in study area ranged from −18 to 9 mm/a from 2015 to 2018, and the maximum subsidence rate exceeded 75 mm/a, the largest subsidence center is located in Wang qingtuo Town, Xiqing District, Tianjin. Furthermore, the SBAS-InSAR-derived result was verified by levelling data. The alignment was relatively high, and the maximum and minimum deviation were 6.4 mm and 3.3 mm, respectively, demonstrating that the SBAS-InSAR technique is feasible to monitor land subsidence in Tianjin area. The main influencing factors with respect to subsidence show different depending on different region. Additionally, the severe land subsidence in Tianjin is mainly caused by rapid urban development and urban surface load increase.