By Alisha Renfro, Coastal Scientist, National Wildlife Federation
Coastal communities throughout the U.S. are increasingly threatened by rising sea levels and extreme weather events. The conventional approach for protecting people and property along the coast has relied on engineering solutions such as levees, seawalls and bulkheads, which “harden” shorelines. However, not only can these structures be expensive to build and difficult to maintain, but in some cases, they can also increase erosion, impair the recreational uses of the area and reduce water quality.
In recent years, efforts to protect coastal communities have been expanded to recognize restoration and conservation of coastal habitats as ways to help buffer coastlines from waves and storm surge. In a study recently published in Nature, “Coastal habitats shield people and property from sea-level rise and storms,” researchers assessed the risk reduction that natural habitats provide to vulnerable people and property and found that loss of the ecosystems that currently exist will result in greater damage to people and property.
Different types of coastal habitat and shoreline offer varying levels of protection to coastal communities depending on their morphology and previously observed ability to offer protection from erosion and flooding. For example, in this study, coastal forests and high cliff shorelines were classified as providing a higher level of protection when compared to marsh and oyster reef habitat, with barrier beach shorelines and areas with no habitat offering the lowest level of protection.
To provide a nationwide view of the risk reduction that could be provided by natural coastal habitat, the researchers in this study compiled a coastal habitat map for the U.S. and compared model runs with and without the habitats under present-day and future sea level scenarios. Their modeling results indicated that, today, 16 percent of the U.S. coastline is classified as a “high hazard” area. When the same conditions were modeled without the presence of protective coastal habitats, the results suggested the extent of U.S. coastline that would be considered vulnerable to storms and sea level rise would double.
Compared to the West Coast, the low-relief Gulf and eastern coasts of the U.S. are more vulnerable to both sea level rise and storms. In order to better protect these vulnerable regions, the authors of this study suggested that large expanses of coastal forests and wetlands, oyster and coral reefs, dunes and sea grass beds are critical.
Recently, some coastal protection plans have begun incorporating conservation and restoration of coastal habitat alongside traditional physical structures. Louisiana’s 2012 Coastal Master Plan is an excellent example of a plan that acknowledges not only the value that coastal habitats have for the fish and wildlife of the area, but it also examines how to combine conservation and restoration of these habitats with traditional engineering strategies to enhance protection for the millions of people that call coastal Louisiana home.