Investigation of land subsidence in Guangdong Province, China, using PS-InSAR technique

Ground subsidence is a natural disaster that can cause severe consequences such as surface deformation and building collapse. With rapid economic growth, activities such as groundwater extraction, subway construction, and large-scale infrastructure projects have weakened the soil’s load-bearing capacity, resulting in subsidence issues for buildings and the ground. As the mechanism of land subsidence caused by the above factors is still unclear, it is necessary to conduct further study in a specific area. Intending to provide a scientific basis for successfully preventing and mitigating the potential risks associated with subsidence, we employed the Persistent Scatterer InSAR (PS-InSAR) technique for monitoring to precisely explore the causes, processes, and impacts of the subsidence. In this study, 14 Sentinel-1A terrain observations by progressive scans (TOPS) Synthetic Aperture Radar (SAR) images from January to December 2020 have been selected to investigate the spatiotemporal ground deformation in the specific Guangzhou and Foshan regions. Various analytical methods have been employed to investigate the significant deformation mechanism. Firstly, we analyzed characteristic points in industrial parks and urban areas. Subsequently, detailed investigations were conducted in three severely subsiding areas: Huadu, Nanhai, and Haizhu districts. Results demonstrate that the region’s surface deformation is highly heterogeneous; subsidence is primarily concentrated in urban areas and usually spreads outward from city centers. Additionally, numerous uplift regions were identified, with the maximum uplift rate exceeding 29 mm/yr. In particular, the highest rates of subsidence were found in Guangzhou’s Haizhu District, with annual average rates ranging from −28.3 mm/yr to −29.4 mm/yr, and significant seasonal fluctuations of nonlinear subsidence patterns have also been detected. Furthermore, comparative analysis of factors such as urban development (e.g., subway systems and artificial structures), rainfall, and industrial expansion in major subsidence areas indicates that subsidence in this region is primarily influenced by anthropogenic factors (such as industrial development and surface loading) as well as natural factors like rainfall and karst processes.