Monitoring and Risk Assessment of Urban Surface Deformation Based on PS-InSAR Technology: A Case Study of Nanjing City

This article carries out high-precision time-series deformation monitoring of the main urban area of Nanjing based on persistent scatterer In-SAR (PS-InSAR) technology and obtains reliable spatial distribution maps of surface deformation rate in the study area. Based on the obtained time-series data, the surface deformation pattern is extracted, the risk level of subsidence hazard is classified, and the spatial and temporal evolution patterns of typical areas are analyzed to further explore the causes of ground subsidence in the study area. The results show that the maximum subsidence rate in the main urban area of Nanjing from 2018 to 2023 reaches 23 mm/yr, and the cumulative subsidence reaches 50 mm. The total area of the subsidence high-risk zone is about 2.3 km2, which accounts for 0.4% of the total area of the main urban area, and the risk of ground subsidence is relatively low. A small part of the surface subsidence area is concentrated in the zone near the Yangtze River, which needs to be focused on. This article proved that the combination of the PS-InSAR method and subsidence risk assessment is effective for urban surface deformation monitoring, and the results of this article can provide a scientific and reliable basis for urban management.