Fig 3. Costs versus water depth and wave height reduction extents of Nature-based Defence (NbD) projects and alternative breakwaters.

Costs of NbDs and cost curves of alternative breakwater structures plotted versus water depth are plotted for a) mangroves (n = 7) and breakwaters in Vietnam and; b) salt-marshes (n = 6) and breakwaters in Europe/USA. Circles represent NbDs and lines represent submerged breakwaters cost-curves in both panels. NbDs that fall below breakwater cost curves are cost effective in comparison. Breakwater cost curves are for an incident wave height Hsi of 0.2 m. All costs are represented on a per-metre coastline length basis (see Methods). Fig only shows mangroves and marshes as these were the only habitat types and locations for which project information was found in close proximity to field measurements.