Open-Source Sentinel-1 SBAS InSAR Monitoring of Ground Deformation in Pantnagar (Indian Terai) Using HyP3 and MintPy

Abstract

Aims: The study aims to measure ground-surface displacement and assess land subsidence along the under-monitored Terai belt of the Himalayan foothills using an open-source remote-sensing workflow. Study Design: Observational time-series analysis utilising satellite radar interferometry to monitor surface deformation. Place and Duration of Study: Pantnagar region, Udham Singh Nagar district, Uttarakhand, with acquisitions covering 8 January 2023 to 21 June 2026. Methodology: Sentinel-1 interferograms were generated via the Alaska Satellite Facility’s HyP3 service and analysed using MintPy with the Small Baseline Subset (SBAS) method across 88 acquisitions. Following network inversion and digital elevation model error correction, pixels were masked at a temporal coherence threshold of 0.7, retaining 80.8% of the ~40 m grid. Results were evaluated against Dynamic World land-cover data, rainfall, and modelled groundwater storage. Results: Most of the scene remained stable, showing a median line-of-sight velocity of −0.4 cm yr−1 (interquartile range: −1.2 to 0.0 cm yr−1; 1σ uncertainty: 0.06 cm yr−1). A distinct, linear subsiding zone in the south-west reached ~−6.1 cm yr−1, representing roughly 21 cm of cumulative line-of-sight displacement over 3.45 years. This deformation persisted over cropped farmland and showed no seasonal rebound during monsoons. Conclusion: The persistent, non-rebounding subsidence points to inelastic aquifer-system compaction driven by sustained irrigation pumping. Although the rates remain provisional because nearby ground-station verification is unavailable, this methodology provides a reproducible template for regional Terai subsidence monitoring.