Mapping Land Subsidence Risk in Warri Using InSAR Remote Sensing

Warri, a major oil industry hub in Delta State, is situated on low-lying sedimentary terrain susceptible to land subsidence from groundwater extraction, oil production, and natural compaction. This study estimates land subsidence rates in Warri metropolis using the Interferometric Synthetic Aperture Radar technique applied to Sentinel-1 SAR image pairs acquired between 2020 and 2023. Persistent scatterer InSAR analysis produces high-density surface deformation maps in the line-of-sight direction. Subsidence rates are analysed in relation to groundwater abstraction well locations, oil field operational data, and geological stratigraphy. Results indicate maximum subsidence rates of 12 millimetres per year in the Pessu and Ogbe-Ijoh areas, coinciding with zones of intensive groundwater extraction and reclaimed land. The study highlights the cumulative risk of combining natural consolidation with anthropogenic extraction in an already low-elevation coastal environment. Recommendations for groundwater abstraction regulation and infrastructure risk zoning are directed at the Delta State Ministry of Environment. Keywords: land subsidence, InSAR, Warri, Sentinel-1, groundwater