Assessment of Coastal Erosion Risk in Lagos State Linked to Storm Surge and Sea Level Rise

Coastal erosion in Lagos State represents an escalating geophysical and meteorological hazard, driven by the combined forces of storm surge events, longshore sediment transport dynamics, and the compounding pressure of sea level rise. This study assesses coastal erosion risk along selected sections of the Lagos coastline, linking meteorological forcing conditions including storm surge height and wave energy with observed shoreline retreat rates. Historical shoreline positions were extracted from multi-temporal Google Earth imagery (2010, 2015, 2022) and measured using the Digital Shoreline Analysis System (DSAS) tool in ArcGIS. Storm surge records from the Lagos Port meteorological station and wave energy estimates derived from ERA5 reanalysis data were used as independent meteorological forcing variables. Results indicate that sections of the Bar Beach and Kuramo Beach coastlines have retreated by 25 to 48 metres over the 12-year study period, with erosion rates accelerating significantly following major storm surge events in 2020 and 2022. Regression analysis confirms that storm surge height is the strongest predictor of episodic shoreline retreat, accounting for 64 percent of variance in annual erosion rates. Projected sea level rise of 15 to 30 centimetres by 2050 under moderate emission scenarios is estimated to increase storm surge heights and coastal erosion rates by 12 to 18 percent. Recommendations include enforcement of coastal setback regulations and construction of groin structures at high-erosion sites. Keywords: coastal erosion, storm surge, Lagos, sea level rise, shoreline retreat.