Stabilization of Grand-Lahou sandy belt
Preserving an estuarine area with a soft solution to protect against erosion, flooding and marine submersion
CONTEXT & ISSUES
A case study in coastal erosion, Grand-Lahou has become a pilot project under the World Bank’s West Africa Coastal Areas Management Program (WACA). The project consists of stabilising a sand belt to protect the village of Lahou Kpanda. Located to the immediate west of the mouth of the Bandama river, on the coastline of the Tagba lagoon, this village is subject to rapid coastal erosion and risks of flooding and marine submersion.
The pre-feasibility study, conducted by Artelia in 2020, led to a concerted decision on a solution for stabilising the channel based on several developments: filling in the existing channel, opening a new channel 3 km to the east, implementing soft solutions to maintain the western bank and drawing up a plan for dredging the channels of the lagoon. The recharging and revegetation of the sandy belt has also been scheduled.
The stability of the proposed structures was tested using a physical sediment model and a digital morphodynamic model. Furthermore, our teams were able to verify the viability of the scheduled maintenance operations to ensure the long-term sustainability of this soft solution.