Dual Impacts of Urbanization and Precipitation on Subsidence in Chongqing Revealed by SBAS-InSAR

Abstract

Abstract Rapid urbanization in Southwest China has exacerbated ground subsidence, imposing severe threats to infrastructure and the environment. However, an understanding of the intricate multi-factorial mechanisms inducing urban subsidence remains inadequate. This study harnesses 44 Sentinel-1A images and InSAR to gauge spaciotemporal patterns of urbanized subsidence in Chongqing from 2021–2022. 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. Whereas 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.