The application of the SBAS-PSInSAR method in monitoring surface deformation in Choushui River Fluvial Plain, Taiwan

Natural processes like tectonic activities and soil consolidation can induce land subsidence, as can human activities such as groundwater or oil extraction, mining, and construction. Among the issues stated, groundwater extraction substantially contributes to global subsidence. In the long term, land subsidence can cause unanticipated building and infrastructure damage, resulting in significant financial consequences for governments. Therefore, it is critical to monitor subsidence regularly to inform policy decisions and control the factors contributing to land subsidence.

The research area for this study is the Choushui River Fluvial Plain (CRFP), located in Taiwan's central region. The CRFP is a major agricultural zone and includes a Taiwan High-speed Rail system (THSR) segment. Monitoring and analyzing land subsidence patterns in the CRFP is critical for local governments to reduce the impact of subsidence on civilian life and public transportation.

This study utilized the SBAS-PSInSAR technique to process multiple Sentinel-1’s SAR images and assess the surface deformation in the CRFP. The results indicated three sinking locations in the northern half that could not be previously recorded by point-wise measurement interpolation, indicating the possibility of identifying local deformation of this InSAR-based method. Furthermore, it also detected a massive subsidence funnel with a sinking rate of up to -60 mm/year in the vicinity of the THSR railway in the south, which might potentially threaten railway safety. Last but not least, the obtained results demonstrated the compatibility of the SBAS-PSInSAR and conventional geodetic approaches in monitoring large-scale surface deformation.