Monitoring Ground Displacement of Large-Scale Landfills in Wuhan Using Time-Series InSAR Technology

Objectives: With the acceleration of urbanization, landfills have become a primary and economically viable solution for the safe disposal of solid waste. The stability monitoring of them is of great significance for ensuring the safety of urban residents' lives and property. Methods: Taking the Chenjiachong and Changshankou municipal solid waste landfills in Wuhan as examples, based on Sentinel-1 SAR images from two adjacent tracks (Path 113 and Path 40), this paper obtains ground deformation information of two large landfill sites in Wuhan urban areas by using small baseline subset interferometry synthetic aperture radar (SBAS InSAR) technology, from 2017 to 2024. To further analyze the seasonal, multichannel singular spectrum analysis (MSSA) was used to reconstruct surface deformation and ERA5-derived temperature and rainfall patterns. Conclusions: The results indicate that approximately 85% of the study area remained relatively stable, with line-of-sight (LOS) deformation rates ranging from -55.3 to 39.6 mm/year for Path 113 and -47.3 to 22.7 mm/year for Path 40. The maximum LOS subsidence rate at the Changshankou landfill (40.0 mm/year) was observed in the slope area. While the maximum LOS subsidence rate (55.3 mm/year) was located in the central accumulation area at the Chenjiachong landfill. Subsidence at these landfills is primarily influenced by the mechanical compression of the waste body, biochemical processes, temperature, and rainfall, with a lag of approximately 100 days relative to rainfall (correlation of 0.76) and 60 days relative to temperature (correlation of 0.93). The heavy rainfall on June 21, 2019, further accelerated landfill subsidence. This study confirms that InSAR technology can effectively monitor surface subsidence at landfills, offering technical support for landfill safety management and environmental protection.