Land deformation analysis using SBAS-InSAR time series with land cover class-specific coherence filtering for the Mississippi River Delta

This study presents a comprehensive assessment of land deformation patterns across a 22,043 km² area of southeastern Louisiana and coastal Mississippi using Small Baseline Subset Interferometric Synthetic Aperture Radar (SBAS-InSAR) time series analysis from 2020 to 2024. The study processed 461 ascending-path interferometric Sentinel-1 SAR image pairs using the MintPy framework, implementing a minimum temporal coherence threshold and a land cover class-specific coherence thresholds filtering to optimize signal detection across diverse coastal environments. The analysis integrated National Land Cover Database (NLCD) 2021 data to characterize subsidence vulnerability patterns across different land cover types. The research results reveal extreme spatial heterogeneity in land surface deformation, with line-of-sight velocities ranging from − 43.71 mm/year to + 30.23 mm/year. Coherence-based filtering by land cover class (Developed Land, Pasture/Hay/Barren, Grassland/Shrub/Crops and Forest/Wetland/Marsh) produced LULC specific LOS velocity maps. Land cover class-specific coherence threshold filtering produced separate LOS velocity maps for Urban, Barren/Pasture, and Marsh/Agriculture land cover categories, enabling spatially refined deformation characterization across the delta. Results indicate that marsh and wetland areas experience the highest subsidence rates, particularly in organic-rich marshlands and low-elevation areas, while uplift signals are observed in southwestern coastal areas, related to sediment deposition processes. Validation against NOAA CORS GNSS stations (BVHS and GRIS) shows InSAR SBAS LOS velocities of -12.46 mm/yr and − 11.82 mm/yr respectively, compared to GNSS vertical-only rates of -2.5 mm/yr to -5.5 mm/yr. The integration of land cover data in this study proved crucial for understanding deformation mechanisms, as areas with rich organic soils and below-sea level elevations showed accelerate subsidence rates.