Hurricane Sandy caused widespread havoc when it made landfall in the Caribbean and on North America’s East Coast (as a post-tropical cyclone) in 2012. The storm killed more than 40 people in New York City alone. “Never in its recorded history had the city experienced a storm of this size,” local officials wrote in a report. “Never had a storm caused so much damage. Never had a storm affected so many lives.”
As climate change and rising seas promise even more destructive storms, New York and other coastal communities are thinking about how to better protect themselves. Part of New York’s plan is to create “living,” oyster-encrusted barriers off southern Staten Island, to shield the highly vulnerable neighborhood of Tottenville from storm waves. The project—called Living Breakwaters—involves building structures to weaken storm waves, reduce coastal erosion and revitalize the local ecosystem, as well as educating the community.
Large, dense clusters of oysters once helped to protect Tottenville from storm waves and filter surrounding waters. But a combination of dredging, overharvesting and pollution virtually destroyed them. “It used to be that oyster reefs would provide a lot of structural habitat, but now there’s just a sandy bottom,” explains Brad Howe, an associate at landscape architecture firm SCAPE, which designed Living Breakwaters along with a team of engineers and ecologists. Sandy underscored why this kind of ecological degradation is so problematic—the storm hit Tottenville with some of the most powerful waves in the region, causing fatalities and knocking houses off their foundations.
The New York Governor’s Office of Storm Recovery plans to begin building a 3,200-foot array of nine separate barriers, or “breakwaters,” as early as this summer. Each has a stone trunk that sits partly underwater, between 730 to 1,200 feet offshore. The barriers are designed to dissipate wave energy (graphic). Five of them are meant to keep waves under three feet high during a “100-year storm”—an event that has a 1 percent chance of occurring in a given year—in a scenario with 30 inches of sea-level rise. The other four breakwaters will protect against erosion and attenuate waves during smaller storms.
During a storm, “you’ll see waves breaking onto the breakwaters themselves, but you’ll also see waves come through the gaps [between the barriers],” explains Joe Marrone, an engineer at design and consultancy firm Arcadis, who is working with SCAPE on the project. “As they come through the gaps, they spread out, and the height of the waves is reduced,” he says. “So you’ll still see wave action at the shoreline, but there will be significantly smaller waves.”
By reducing the amount of wave energy pounding the shore, the breakwaters should slow erosion and leave more sediment to help build the beach. The gaps between the barriers are meant to allow some natural sediment to migrate and to let the system flush itself out.
Most of the structures will feature fingerlike ridges jutting into the ocean to provide habitat for fish and other aquatic animals. “The idea is to try to structurally mimic naturally occurring reef formations,” Howe says. The breakwaters will incorporate materials that will help support marine life, and a group called the Billion Oyster Project plans to install the bivalves on and around the barriers.
The Living Breakwaters will also include a “floating water hub”—a boat that will serve as an educational space, giving community members and students access to the breakwaters. “It’s about fostering this idea of social resilience, connecting people who live in the community back to the shoreline,” Howe says.
Other places are also trying to build in cooperation with nature—rather than simply trying to hold it back—as they adapt to climate change. The Dutch city of Rotterdam has built “green,” vegetation-covered roofs to absorb rainfall and a public plaza that also serves as a stormwater basin. Norfolk, Va., has developed a strategy to protect some areas from sea-level rise and coastal storms and to withdraw from others. “Even under the current U.S. national [political] climate, there are things happening,” says Phil Berke, a professor of land use and environmental planning at Texas A&M University. “Cities like New York City, Miami, Norfolk and others are doing this on their own.”
Some experts have concerns, however. “Certainly incorporating green aspects makes [projects such as Living Breakwaters] more resilient,” says Katherine Greig, senior fellow at the University of Pennsylvania’s Wharton Risk Management and Decision Processes Center. “But the notion that that’s going to be the answer is troubling to me. Does it give people in those neighborhoods a false sense of security about what their risk is? Are the most vulnerable people going to be protected behind these infrastructure investments?”
SCAPE, however, says it has worked to address such concerns: “Our design team, along with the Governor’s Office of Storm Recovery, has made a continued effort to engage and educate the community of Tottenville about the risks they face now and in the future and about how the Living Breakwaters reduce some of that risk but do not eliminate all risk.”