Numerical Modelling of Potential Sea Level Rise Impacts on Eti-Osa and Ibeju-Lekki Coast, Lagos, Nigeria

The Eti-Osa and Ibeju-Lekki coastlines of Lagos, Nigeria, are increasingly threatened by rising sea levels, heightening the risk of flooding and coastal erosion. Understanding how potential sea level rise will impact this region requires a detailed investigation of its wave, current, and tidal dynamics. This study employs advanced hydrodynamic and spectral wave modelling to simulate tidal variations, storm surges, and sea level changes along the Eti-Osa and Ibeju-Lekki Coast. Using the MIKE 21/3 coupled model, a numerical framework was developed to evaluate observed sea level conditions and project potential future flooding scenarios of + 0.5m, + 2m, + 3m and + 5m. QGIS was further applied to generate inundation maps illustrating flood extents under varying sea level rise scenarios. Model results reveal that the western segment of the study area, Tarkwa Bay Beach and Eko Atlantic City, experiences the highest water levels (0.28–0.95 m) and tidal ranges (0.49–2.98 m) during both the simulation period and projected sea level rise scenarios (+ 0.5m, + 2m, + 3m and + 5m). These findings are consistent with the inundation maps, which show that water level increases are most pronounced along the western axis, under the + 0.5m, + 2m, + 3m and + 5m sea level rise scenarios, respectively. This trend is primarily attributed to the relatively lower elevation and stronger wave activity in the western zone. Overall, the study provides valuable insights into how nearshore hydrodynamic processes drive spatial variations in sea level rise along the Eti-Osa and Ibeju-Lekki Coast.