Monitoring Coastline Changes in Lagos Using Satellite Imagery and GIS

Lagos State's coastline is one of the most dynamic and economically significant coastal systems in West Africa. Rapid urbanisation, sand dredging, and sea level changes are reshaping coastal morphology at an alarming rate. This study monitors coastline changes along the Lagos coast from 2015 to 2023 using Sentinel-2 multispectral imagery and GIS-based change detection. The Normalised Difference Water Index is used to extract waterline positions from multi-temporal imagery, and the Digital Shoreline Analysis System tool is employed to compute rates of accretion and erosion. Results show that erosion dominates along the Victoria Island and Kuramo Beach frontages, with annual erosion rates reaching 3.2 metres per year in the most exposed sections. Conversely, accretion is observed near Eko Atlantic City, reflecting the influence of protective seawall infrastructure. The study highlights the role of unregulated sand mining in amplifying coastal vulnerability. Findings are intended to support the Lagos State Ministry of Waterfront Infrastructure Development in designing adaptive coastal management strategies. Keywords: coastline change, Lagos, shoreline analysis, remote sensing, coastal erosion