Natural Hazards Research Summit 2024: Engineering Design of Emergent Vegetation to Mitigate Wave Overtopping

This poster describes three studies that support the implementation of Nature-based Solutions (NbS), specifically emergent vegetation, for flood risk reduction. NbS are landscape features used for flood risk management. They are increasingly popular due to the additional benefits they confer beyond flood protection, including increased habitat and carbon storage. However, widespread implementation of these systems is lacking. Ostrow et al. (2022) surveyed 32 stakeholders to learn more about barriers to implementation of NbS. We found that in the engineering sector, the most common barrier mentioned was the lack of engineering design standards. To support engineering design standard development, the research group has since investigated performance of emergent vegetation for wave overtopping mitigation. Libby et al. (in review) conducted a large-scale experiment in the O.H. Hinsdale Wave Research Laboratory Large Wave Flume. We compared the overtopping of configurations with wall alone, wall with mangroves, wall with revetment, and wall with both mangroves and revetment. We found that the mangroves reduced overtopping by an amount comparable to the reduction by the revetment. Furthermore, we found that the green and gray components of the hybrid system acted independently. Ostrow and Cox (in review) proposed a performance-based design methodology for design with emergent vegetation. The methodology considered growth and mortality processes, and uncertainties in the system. To demonstrate the methodology, we considered an idealized embayment inspired by Southern Florida, and considered the overtopping onto a coastal road. We found that performance of the mangroves generally improves with time as the mangroves develop. The audience of this poster is natural hazards researchers, and data from the overtopping experiments will be posted on Design Safe.