Dual impacts of urbanization and precipitation on subsidence in Chongqing revealed by SBAS-InSAR

Southwest China’s rapid urbanization has intensified ground subsidence, threatening infrastructure and the environment. However, the complex mechanisms behind urban subsidence are still poorly understood. This study harnesses 44 Sentinel-1 A images and InSAR to gauge spatiotemporal patterns of urbanized subsidence in Chongqing from 2021 to 2022. Results reveal subsidence up to 8 mm/yr across 26 km², with hotspots near subway lines, construction sites, and agricultural regions. Subsidence along metro lines likely stems from excavation and vibrations during operation. The proliferation of high-rise buildings has sharply increased loading, accelerating consolidation and deformation. Agricultural land experiences substantial subsidence due to groundwater extraction. Moreover, precipitation demonstrates a negative correlation with subsidence. Heavy rainfall during spring and summer replenishes soil moisture, alleviating consolidation. Meanwhile, reduced precipitation in fall and winter diminishes support from bedrock, aggravating subsidence. These findings underscore anthropogenic activities as primary drivers of urban subsidence. Monitoring infrastructure and minimizing land conversion is critical for mitigation. This study demonstrates InSAR’s prowess in unveiling subsidence mechanisms, guiding sustainable urban development.