International Guidelines on Natural and Nature-Based Features for Flood Risk Management

At Swan Island, situated in Chesapeake Bay, high rates of shoreline erosion and subsidence deteriorated the island's natural habitat and its ability to shelter the nearby town of Ewell, Maryland, from wave energy. Prior to restoration in 2019, the low-lying portion of Swan Island consisted of fragmented low marsh in danger of further loss. To reverse this trend and restore the island, the U.S. Army Corps of Engineers (USACE), Baltimore District, placed 60,000 cubic yards of dredged sediments on the island, and planted native salt marsh and dune plants.

High tide flooding events are increasing across the nation. With 40% of the U.S. population living in coastal counties and that population projected to increase, it is clear that a significant portion of the nation is increasingly vulnerable to these hazards. The recently published U.S. Army Corps of Engineers (USACE)-led International Guidelines on the Use of Natural and Nature-Based Features for Flood Risk Management represent the current state of the science on conceptualizing, planning, designing, engineering, implementing, and maintaining natural and nature-based feature (NNBF) projects.

The publication of the Guidelines is the culmination of a five-year collaboration between NOAA, USACE, and many international partners, including more than 175 international authors and contributors from more than 75 organizations and 10 countries.

Nature-based solutions are infrastructure projects that use natural features or processes that might otherwise be provided by engineered structures. Salt marshes, for example, provide essential habitat for healthy fisheries while protecting shorelines from erosion by buffering wave action and trapping sediments. These natural systems reduce flooding by slowing and absorbing rainwater, while enhancing water quality by filtering runoff and metabolizing excess nutrients.

The complex challenges of sea level rise, coastal flooding, and increased storm frequency, among other hazards, pose increasing risks to our nation's communities. In the last five years, weather and climate-related disaster events have cost our nation over $630 billion dollars in damages. Solutions that reduce the impacts of coastal hazards, while also addressing the inevitable competition over the use of natural resources for commerce, food, energy, recreation, and conservation, will require innovative methods and approaches that cannot be solely addressed through the use of traditional hardened infrastructure. By using natural infrastructure such as marshes, dunes, reefs, islands, and mangroves to protect coastal communities, we can sustainably improve community resilience. We can also conserve or restore coastal habitats that support commercially important fish, enhancing marine life and opportunities for aquaculture.

The Guidelines provide end-users with information on using NNBF to improve coastal resilience, aligning with NOAA's mission to manage and conserve coastal and marine ecosystems and resources and maintain healthy and resilient ecosystems. The goal of this milestone effort is to advance the use of NNBF and equip decision makers, project planners, and practitioners with solutions that reduce flood and storm risks while providing jobs, preserving commerce and recreation, improving resilience, and producing more environmentally sustainable solutions.

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