Flow-Canopy Interactions Within Mangrove Forest, Oyster Reef and Seagrasses With Applications to Design of Nature-Based Features

Features of aquatic ecosystems such as wetlands, reefs, barrier islands and dunes function as natural infrastructure to reduce risk from environmental hazards. Community interest to restore functionality to degraded ecosystems is moving beyond the boundaries of traditional restoration to include the integration of nature-based features into built infrastructure as an emerging climate adaptation strategy. For instance, new oyster reef may be constructed and combined with planted vegetation within riparian and intertidal zones to create living shorelines. However, the application of living materials to infrastructure involves careful balance, and sometimes trade-offs, between engineering and ecological objectives. In this work, results of field study within natural and restored or engineered biological canopies, including sea grasses, oyster reefs, and mangrove forests, are discussed with reference to nature-based design applications. For example, investigations of mean flow and turbulence above and within canopies of intertidal Eastern oyster (Crassostrea virginica) indicated that restored reefs were hydrodynamically similar to historically healthy reefs within a year of restoration. This is an important finding for coastal managers wanting to restore ecosystem services associated with live reefs. However, while created reefs built within living shoreline stabilization often met engineering objectives of flow attenuation and sediment accretion, they sometimes failed to recruit oyster. To optimize among multiple benefits of nature-based features, the study of Ecohydraulics and Ecomorphodynamics has much to contribute towards understanding the hydrogeomorphic interactions that influence the ultimate impact and longevity of such features.