Infrastructure subsidence monitoring — detecting millimetre-scale vertical displacement of critical assets over time — has traditionally relied on geodetic survey benchmarking programmes that provide point measurements at months-long intervals at costs of $500–$2,000 per benchmark per campaign. For a large dam with 200 survey monuments, an annual monitoring programme costs $100,000–$400,000 in survey labour alone, while the point sampling density provides limited spatial coverage of differential settlement patterns that may indicate localized foundation problems. InSAR (Interferometric Synthetic Aperture Radar) processing of Sentinel-1 time-series offers a fundamentally different monitoring paradigm: spatially continuous displacement maps at 5m×20m pixel resolution, updated every 6 days, at data acquisition cost of zero.
The Persistent Scatterer InSAR (PS-InSAR) processing chain for infrastructure monitoring involves several critical steps: Sentinel-1 GRD product coregistration to a common reference geometry using precise orbit files; interferogram formation across all image pairs in the time series; PS candidate identification using amplitude stability index thresholding (typically σ/μ < 0.25); phase history analysis using StaMPS or SNAP-StaMPS algorithms to separate deformation signal from atmospheric noise; and velocity map generation using linear regression against the temporal baseline. For concrete dam structures with high backscatter stability, PS densities of 500–2,000 persistent scatterers per km² are achievable — providing spatial resolution comparable to dense survey networks.
Detection thresholds for operational infrastructure monitoring applications depend on atmospheric noise mitigation. Raw InSAR displacement measurements contain atmospheric phase screen contributions from tropospheric water vapour variability that can reach 3–5mm of apparent displacement per acquisition. ERA5 reanalysis-based atmospheric correction reduces tropospheric noise to approximately 1mm RMS, enabling detection of true structural displacement at the 2–3mm/year threshold with high statistical confidence after 2 years of time-series accumulation. For alert generation applications — triggering engineering inspection when displacement rate exceeds a threshold — the combination of PS-InSAR velocity maps and GPS corner reflector reference points provides both the spatial coverage and absolute accuracy required for regulatory reportable condition assessments.
The Prime Logic Monitoring Command Center integrates automated Sentinel-1 InSAR processing for critical infrastructure clients, delivering spatially continuous subsidence velocity maps updated on 12-day Sentinel-1 repeat cycles, PS-InSAR time-series dashboards with alert thresholds configurable by asset type and engineering risk classification, and automated regulatory notification workflows for dam safety programmes. The GIS Dashboard Suite visualizes deformation patterns overlaid on asset engineering drawings, LiDAR point clouds, and geotechnical investigation datasets — enabling structural engineers and dam safety regulators to correlate observed settlement patterns with subsurface conditions and identify anomalous deformation zones requiring targeted ground investigation.