Mapping persistent oil spill risk in the Niger Delta using Sentinel-1 SAR and environmental exposure indicators

Oil spills remain a major source of marine and coastal pollution in hydrocarbon-producing regions, where repeated releases can lead to long-term contamination of wetlands, waterways, and adjacent communities. Although satellite remote sensing has improved the detection of oil spills, translating these observations into assessments of cumulative environmental and human exposure is still challenging, particularly in complex deltaic systems. Here, we present a spatially explicit framework for assessing persistent oil spill exposure in the Niger Delta by integrating Sentinel-1 synthetic aperture radar (SAR) observations with ecological, infrastructural, terrain, and demographic data. Rather than focusing on individual spill events, we quantify chronic exposure patterns by finding recurring oil spill signatures and combining them within a multi-criteria risk model. Our results reveal persistent contamination hotspots strongly associated with dense oil infrastructure, low-lying wetlands, flat terrain, and high population density, collectively affecting approximately 9400 km² over the past decade. Spill exposure extends beyond reported incident locations and includes both protected and upland areas, showing widespread vulnerability across the delta. These findings show that long-term pollution risk in the Niger Delta is governed by cumulative exposure and landscape controls rather than isolated spill events alone. The proposed framework provides a transferable approach for monitoring, assessing, and managing chronic oil pollution in coastal and deltaic environments worldwide.