| Surface subsidence is one of the major geological disasters in Tianjin area, which has a serious negative impact on social stability and economic development, and causes huge economic losses every year. Therefore, it is necessary to carry out wide-area and efficient monitoring of surface subsidence. The 48 scenes ascending Sentinel-1A images and 48 scenes descending Sentinel-1B images of Tianjin area from January 2017 to December 2020 were used to monitor the surface subsidence based on Small Baseline Subset InSAR (SBAS-InSAR) technology. The surface subsidence rate and cumulative subsidence results of Tianjin area were obtained. Moreover, the accuracy and reliability of monitoring results were verified by internal coincidence accuracy and existing study results. The spatiotemporal variation characteristics and evolution laws of subsidence were analyzed, and a key study was conducted on typical subsidence areas based on subsidence profiles and land use types. The results show that the subsidence distribution characteristics monitored by the data of ascending and descending orbits are basically the same. The subsidence distribution in Tianjin area is wide and the spatial distribution is uneven. Specifically, the six districts in Tianjin are relatively stable, and five typical subsidence funnels are formed around the urban area, mainly concentrated in Wangqingtuo Town in Wuqing District, Shengfang Town in Bazhou City, Tuanbo Town in Jinghai District, Wangwenzhuang Town in Xiqing District and Balitai Town in Jinnan District. During the monitoring period, the maximum surface subsidence rate reached 127.35mm/a, and the maximum cumulative subsidence amount reached 378.21mm. It is found that the subsidence of Tianjin area is closely related to the over-exploitation of groundwater, the development of urban infrastructure and the construction of large-scale projects. The study shows the reliability of InSAR technology in monitoring surface subsidence in large areas, and the research results can provide data support and important decision-making basis for subsidence prevention and control, and provide reference significance for urban construction in Tianjin. |