Nature-Based Solutions for Coastal Highway Resilience: An Implementation Guide
Nature-based solutions can serve as a first line of defense and improve the resilience of coastal highways. FHWA developed Nature-Based Solutions for Coastal Highway Resilience: An Implementation Guide to help transportation professionals understand when, where, and which nature-based solutions may work for them. The guide follows the project implementation process from planning all the way through construction and maintenance.
Nature-based solutions provide risk-reduction benefits to coastal highways by reducing coastal flooding, wave heights, and erosion. These reductions are the result of both physical and biophysical processes, underscoring the importance of the ecological components of a nature-based solution. Vegetative features like tidal marshes, mangroves, and maritime forests can reduce coastal flooding and effectively dissipate wave energy that contributes to wave-induced flooding, erosion, and infrastructure damage. Reefs dissipate wave energy and force waves to break further from shore, leading to reductions in wave runup and overtopping, wave energy, and erosion. Beaches and dunes dissipate wave energy and reduce coastal flooding and are known to effectively minimize damage to the built environment during extreme events.
Nature-based solutions offer habitat, water quality, and recreational benefits. The natural aquatic edge or shoreline, provision of substrate, and/or use of structures like marsh sills or breakwaters provide habitat for juvenile finfish and shellfish as well as foraging opportunities for birds and mammals. Water quality improvements result from reductions in available nitrogen, phosphorous, and total suspended solids. The habitat and water quality benefits combine to produce beneficial opportunities for recreational fishing, kayaking, paddle boarding, and bird watching.