Numerical modelling of sediment transport in southwest coast of Nigeria: Implications for sustainable management of coastal erosion in the Bight of Benin

Abstract

Coastal erosion is widespread across the Bight of Benin owing to the perturbation of the sediment transport by the installation of the major ports of Lomé (Togo), Cotonou (Benin), and Lagos (Nigeria), among other factors. While different coastal management measures have been put in place to mitigate the effects of this hazard, they have seldom lessened the damage caused by it. To this end, this study examined the coastal processes in Southwest Nigeria (Barrier-Lagoon and Mud coast sections) through the numerical modelling of the hydrodynamic, spectral-wave, and sediment transport for three months to apprehend the poor performance of the management measures. Model results reveal that the nearshore current is mainly directed eastward with the persistent exposure of the area to wave-action. Two major sediment transports; the eastward/south-eastward and westward/north-westward sediment transports, were also identified. The predominance of these sediment transport patterns implies that the continuous adoption of reactive, site-specific hard-engineering coastal management approaches will give counter-productive results. Thus, to sustainably manage the coastal erosion problem across the Bight of Benin, there is the need to adopt a long-term, regional perspective with a cascade of coastal management measures covering all areas under the influence of the predominant sediment transports.