A Low-Cost Nature-Based Solution for Coastal Dune Restoration: The Case Study of AlgoBox in South Brittany, France

Sedrati, M.; Dalour, L.; Bulot, G., and Metge, N., 2024. A low-cost Nature-Based Solution for coastal dune restoration: The case study of AlgoBox in south Brittany, France. In: Phillips, M.R.; Al-Naemi, S., and Duarte, C.M. (eds.), Coastlines under Global Change: Proceedings from the International Coastal Symposium (ICS) 2024 (Doha, Qatar). Journal of Coastal Research, Special Issue No. 113, pp. 1082-1086. Charlotte (North Carolina), ISSN 0749-0208. Preventing marine submersion and coastal erosion is a major challenge in the most coastal areas because of increasing vulnerability of human issues. Awareness of the decline in biodiversity and degradation of coastal ecosystems has led to emergence of nature-based solutions, more sustainable and resilient than traditional coastal engineering. On sandy coasts, the AlgoBox system is a sustainable ecological solution for preserving the coastline and restoring dunes, first natural barriers against waves. This tool combines the use of sand-trapping fence cases with filling by algae wrack. The addition of algae to the box helps to dampen waves and provides nutrients for plants colonisation, responsible for fixing sediments. The AlgoBox system has been implemented for several years on various beaches in Morbihan, France. The evaluation of the “AlgoBox” including regular topographic dune-beach profile surveys and vegetation colonization processus in order to evaluate it effectiveness in different weather and hydrodynamic conditions, especially during storms. The results show that these low-cost nature-based solutions have successfully increased sediment levels and regeneration dune. Overall, AlgoBox have had the positive effects of (1) stabilising the coastline and preventing it from retreating during storms (2) forming an embryonic dune and (3) enriching coastal vegetation.