Use Nature, Not Seawalls, to Defend from Storms

A Living Shoreline replaced a failing bulkhead at the N.C. Wildlife Resource Commission’s Edenhouse boat ramp on the Chowan River. Photo by the North Carolina Coastal Federation

From the Harvard Gazette, an article by Colleen Walsh on the environmental damage and lack of success in general from manmade seawalls:

For years coastal homeowners have tried to beat back Mother Nature with seawalls, imposing structures of wood and/or concrete intended to fend off angry tides and surging storms. But emerging research suggests that in some areas, biological barriers both better protect against erosion and preserve vital ocean habitats.

Not only have seawalls in certain areas been shown repeatedly to fail when tested, but they pose a threat to the delicate ecosystems associated with wetlands and intertidal areas, Rachel Gittman, a postdoctoral research associate at Northeastern University’s Marine Science Center, said during a talk at Radcliffe on Thursday. Instead of absorbing energy generated by wind and waves, seawalls reflect that force back into the water, said Gittman, further eroding the shore and erasing important habitats for fish, crabs, and shore birds.

“You are essentially talking about a little over a 25 percent loss in biodiversity and also around a 35 to 40 percent loss in abundance when you have a seawall instead of a natural shoreline.”

Gittman’s talk was part of the Radcliffe Institute for Advanced Study’s “Next in Science,” a new program that brings together early career scientists to present their research to the Harvard community and the public. The session, which included speakers from the University of Glasgow and the Sea Education Association, was a preview of Radcliffe’s October ocean symposium, “From Sea to Changing Sea,” as well as a series of upcoming ocean-related talks.

Gittman’s graduate research along the North Carolina coast in the aftermath of Hurricane Irene in 2011 suggests that the use of “living shorelines” instead of seawalls “can protect private property from these coastal hazards without compromising the habitats.” (The National Oceanic and Atmospheric Administration defines a living shoreline as one that “uses plants, sand, and limited use of rock to provide shoreline protection and maintain valuable habitat.”)

In an area of North Carolina hardest hit by the hurricane, Gittman observed “75 percent of the bulkheads had some kind of damage,” while other types of shorelines, including living shorelines, were damage-free.

While such living shorelines won’t work everywhere, they are often a viable option, said Gittman, who helped North Carolina residents plant sea grass for their living shorelines as part of her research. “And with the right amount of education and incentives,” she added, “it’s possible we could push private-property owners in the direction of thinking about the long-term sustainability and resilience and ecological function of their shorelines rather than just ‘I want my property to stay exactly the way it is for the next 30 years.’”

Read the remainder of the article, focused on whale communication, here.

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