Multi-Scale Time Series InSAR Integrated with ICA for Deciphering the Coupling Mechanism Between Groundwater Dynamics and Surface Deformation

Land subsidence has become an increasingly serious environmental problem worldwide, especially in areas where groundwater is over-exploited. Hengshui City, as part of the North China Plain in eastern China, has been experiencing increasingly severe land subsidence due to long-term groundwater over-exploitation, which has seriously affected local infrastructure and the sustainable utilization of water resources. In order to explore the relationship between hydraulic head changes and subsidence, this study systematically analyzed the ground subsidence characteristics and its driving mechanism in the Hengshui area from January 2018 to July 2022 using the time series InSAR (interferometric synthetic aperture radar) technique combined with independent component analysis (ICA). The subsidence signals were decomposed into seasonal, trend, and stochastic features by independent component analysis, revealing the multi-scale time lag effect of hydraulic head fluctuations on subsidence. The results show that the magnitude of land subsidence is increasing under the condition of a continuously decreasing water level, reflecting the groundwater compaction problem triggered by the over-exploitation of groundwater. This study provides a theoretical basis and technical support for groundwater management and subsidence prevention and control in Hengshui and similar regions.