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A prototype-scale physical model was used to study wave height attenuation through an idealized mangrove forest and the resulting reduction of wave forces and pressures on a vertical wall. An 18 m transect of a Rhizophora forest was constructed using artificial trees, considering a baseline and two mangrove stem density configurations. Wave heights seaward, throughout, and shoreward of the forest and pressures on a vertical wall landward of the forest were measured. Mangroves reduced wave-induced forces by 4%–43% for random waves and 2%–38% for regular waves. For nonbreaking wave cases, the shape of the pressure distribution was consistent, implying that the presence of the forest did not change wave-structure interaction processes. Analytical methods for determining nonbreaking wave-induced loads provided good estimations of measured values when attenuated wave heights were used in equations. The ratio of negative to positive force ranged between 0.14 and 1.04 for regular waves and 0.31 to 1.19 for random waves, indicating that seaward forces can be significant and may contribute to destabilization of seawalls during large storms. These results improve the understanding of wave-vegetation-structure interaction and inform future engineering guidelines for calculating expected design load reductions on structures sheltered by emergent vegetation. 

Coastal and nearshore communities face increasing coastal flood hazards associated with climate change, leading to overland flow and inundation processes in the natural and built environments. As communities seek to build resilience to address these hazards, natural infrastructure (e.g., emergent vegetation) and hybrid designs have been identified for their potential to attenuate storm-driven waves and associated effects in developed nearshore regions. However, challenges remain in robustly characterizing the performance of natural systems under a range of incident hydrodynamic conditions and in bridging interdisciplinary knowledge gaps needed for successful implementation. This paper synthesizes field and laboratory results investigating the capacity of Rhizophora mangle (red mangrove) systems to mitigate wave effects. Results indicate that R. mangle forests of moderate cross-shore width have significant effects on wave transformation and load reduction in sheltered inland areas. Opportunities for future interdisciplinary collaborations are also identified. 

This project investigated the potential of mangroves of modest cross-shore thickness to attenuate wave heights and reduce loads on sheltered structures through a prototype-scale physical model. Two forest densities and a baseline case were considered, and transient, regular, and irregular waves generated over the 18 m mangrove test section. Water surface elevations seaward, throughout, and leeward of the mangrove forest were measured, as well as pressures on a test wall positioned behind the forest test section.