The development of Lekki beach into a high-end residential development is under threat from the sea. The proposed development was placed on a rapidly eroding coastline. The proposed residential plots closest to the sea are already inundated with water at high tide, and the beach is eroding.
Royal HaskoningDHV was contracted to assess the coastal erosion problem and define a sustainable solution.
Using numerical models including LITLINE and XBeach, our team analysed the prevailing longshore and cross-shore transport along the Lekki coast. Model results revealed that the existing groyne defences along the coast are effective at preventing the transport of sand along the coast. However, during extreme storm events, large swell waves take large quantities of sand from the beach into the ocean. Such offshore transport of sediment is not rapidly recoverable by natural processes. Intervention is required to avoid unacceptable erosion of the beach.
Royal HaskoningDHV was subsequently contracted for a study to identify feasible engineering options for defending the coastline from the harsh Atlantic swell waves. Our team of coastal engineers came up with several options and discussed the risks and costs of each option with our client and the proposed contractor.
Based on our assessments and predictions, the client decided on further steps to protect its valuable beach.