How Nature Protects Communities from Flooding

Sadly, the 2017 hurricane season will long be remembered.

Our thoughts and condolences go out to those who are suffering due to the devastation and unprecedented flooding caused by the hurricanes that have pummeled through the Atlantic Ocean, Caribbean Sea and Gulf of Mexico this season. As news reports have shown, hurricanes Harvey, Irma and Maria have been exceptionally destructive. 

This page suggest ways in which nature can help reduce flood risk for communities. Reducing the risks that storms pose always involves multiple solutions working in tandem. These solutions include: early warning systems; manmade or “built” solutions like reservoirs, dams, levees, seawalls and pumps; working with willing communities and homeowners to move people out of areas that are subject to frequent flooding, and; nature itself, which we call “nature-based solutions” or “natural infrastructure.” But, sadly, there are some storms so severe that they inundate even the best, holistic systems designed to reduce flood risk—Hurricanes Harvey, Irma and Maria were such storms.


Aerial views of the damage caused by Hurricane Sandy to the New Jersey coast taken during a search and rescue mission by 1-150 Assault Helicopter Battalion, New Jersey Army National Guard, Oct. 30, 2012. © Master Sgt. Mark C. Olsen/U.S. Air Force

Aerial views of the damage caused by Hurricane Sandy to the New Jersey coast taken during a search and rescue mission by 1-150 Assault Helicopter Battalion, New Jersey Army National Guard, Oct. 30, 2012. © Master Sgt. Mark C. Olsen/U.S. Air Force


Harvey, Irma, and Maria are painful reminders as Sandy’s 5-year anniversary nears.

Hurricanes Harvey, Irma and Maria struck as we at The Nature Conservancy were reflecting on Hurricane Sandy and the destruction it brought with it. Sandy made landfall in New Jersey five years ago on October 29. Sandy was deemed the second costliest hurricane in U.S. history (behind Hurricane Katrina), but it also hit Jamaica, Cuba and the Bahamas hard. Sadly, Sandy, Harvey, Irma and Maria are not anomalies—since 2005, five hurricanes have caused a total of more than 2,200 deaths and some $230 billion in damages in the U.S. alone, and these figures do not include Harvey, Irma, Maria or Hurricane Matthew, which struck in 2016, killing 546 people in Haiti and 47 in the United States. Experts are now predicting Harvey may end up costing as much as or more than Katrina.

The severity and impacts of these storms are growing worse. But there is a role that nature itself can play in helping reduce flood risk for communities while providing other benefits, like improved water quality and enhanced recreational opportunities and wildlife habitat, all of which can also enrich local economies.


Dunes provide protection at South Seaside Park, N.J. © Cara Byington/The Nature Conservancy

Dunes provide protection at South Seaside Park, N.J. © Cara Byington/The Nature Conservancy


Dunes provide protection at South Seaside Park, N.J.

In December 1992, a Nor’easter caused significant flooding and erosion at South Seaside Park, in part because naturally occurring dunes there had been removed years before to improve ocean views and beach access. After the 1992 Nor’easter the community used snow fencing to help rebuild the dunes and then stabilized them by planting dune grasses. When Hurricane Sandy hit in 2012, the dunes were 25 feet high and 150 feet wide. During the storm, these dunes protected the community from severe damage and flooding along the ocean front. The dunes, rather than homes, businesses and infrastructure, took the brunt of the storm.

South Seaside Park also serves as a case study for the Naturally Resilient Communities program, which is a partnership of county governments, professional engineers, community planners, floodplain managers and conservationists who work with communities to improve their quality of life and economies through the use of nature-based solutions.


The South Cape May Meadows Preserve is included among the case studies at NRCSolutions.org that demonstrate the successful use of nature-based solutions that help reduce flood risk while providing other benefits for communities. © Erika Nortemann/The Nature Conservancy

South Cape May Meadows Preserve demonstrates the successful use of nature-based solutions to help reduce flood risk while providing other benefits for communities. © Erika Nortemann/The Nature Conservancy


Beaches and wetlands reduce flood damage at South Cape May, N.J. 

The Nature Conservancy owns and manages the 200-acre South Cape May Meadows Preserve, where we have worked with partners to restore wetlands and sand dunes that have helped protect the neighborhood located behind them from the impacts of several storms, including Hurricane Irene in 2011 and Sandy in 2012. This natural infrastructure protected Cape May Point during Hurricane Sandy against the third highest storm surge experienced since Hurricane Gloria in 1985. The restored wetland absorbed nearly 10 inches of rainfall—also the highest recorded since 1985—resulting in minimal damage to nearby neighborhoods.

In 2014, Conservancy scientists produced an analysis of the economic and social benefits of the ecological restoration at South Cape May. They found that the restoration helped reduce the average flood damage per storm from $143,713 to $3,713 (for the same level of storm surge). During Sandy, nourished beaches on New Jersey’s Atlantic Coast reduced the likelihood of severe damage or destruction to “first row” homes and businesses by 50 percent. Watch a recent news story online.


Volunteers work to restore oyster reefs in Mobile Bay, Alabama. © Erika Nortemann/The Nature Conservancy

Volunteers work to restore oyster reefs in Mobile Bay, Alabama. © Erika Nortemann/The Nature Conservancy


Oyster reefs reduce wave energy. 

In 2008, the National Oceanic and Atmospheric Administration (NOAA) Restoration Center provided $167 million for habitat restoration projects through the American Recovery and Reinvestment Act. The Nature Conservancy was selected to lead eight coastal restoration projects totaling approximately $24.5 million.

Several of these projects involved the restoration of natural features that help reduce risk for coastal communities, such as oyster reefs in Alabama and Virginia. At these two project sites, the Conservancy worked with partners to restore 27 acres of oyster reefs and 130 acres of seagrass beds, both of which have been proven to help improve water quality, help reduce shoreline erosion, and provide valuable habitat for fish, blue crabs and other marine animals. The two projects also created nearly 100 jobs, and more than 500 volunteers logged over 2,400 hours to restore oyster reefs at Alabama’s Mobile Bay. Across the U.S., The Nature Conservancy has worked with partners and volunteers to restore over 760 acres of oyster reefs.


The Nature Conservancy is working to restore healthy coral reefs along Florida’s unique reef track that runs between the Dry Tortugas and Fort Lauderdale. © Carlton Ward, Jr.

The Nature Conservancy is working to restore healthy coral reefs along Florida’s unique reef track that runs between the Dry Tortugas and Fort Lauderdale. © Carlton Ward, Jr.


Coral reefs help protect coastal communities.

Coral reefs can reduce wave energy by an average of 97 percent before they reach shore, and coral reef restoration highly cost effective at reducing flood risk compared to artificial solutions. Recovery Act funding from NOAA’s Restoration Center also included support for Conservancy-led coral reef restoration projects in Florida, the U.S. Virgin Islands and Hawaii. In Florida and the U.S. Virgin Islands, the funding was used to create 35 coral reefs at eight locations. The innovative work included growing cuttings of coral on cement blocks in water nurseries around the Florida Keys and then transplanting them to restoration sites.

In Hawaii, the restoration efforts focused on removing some 2,200 tons of invasive algae that harms coral, while also working with the community at Maunalua Bay to increase coral reef protection and stimulate local entrepreneurial investments in coastal and marine habitat restoration, which in turn helps boost the local economy. Combined, these projects in Florida, the USVI and Hawaii created or directly supported some 135 jobs. The Conservancy has also restored reefs in Grenada that now help reduce flooding and coastal erosion for a local fishing town there. 


Mangrove displaying impressive arching underwater root system in the Exuma Cays Land and Sea Park, Bahamas. © Jeff Yonover

Mangrove displaying impressive arching underwater root system in the Exuma Cays Land and Sea Park, Bahamas. © Jeff Yonover


Mangroves: formidable defenses against storms.

While oyster and coral reefs can reduce wave energy, studies have shown that mangroves can reduce wave heights by 66 percent and reduce coastal surges, making these forests formidable defenses for coastal communities. Mangroves also provide extremely valuable habitat for fish and wildlife and possess an enormous capacity to sequester (or store) carbon (or greenhouse gasses).

Working with the World Bank, The Nature Conservancy has shown that mangroves reduce the cost of flood damage by 25 percent every year. The Conservancy’s president, Mark Tercek, and its lead marine scientist, Mike Beck, recently co-authored an article touting the many benefits—including flood risk reduction and carbon sequestration—that mangroves provide.


Marsh and grasses at Guerin Creek, a tributary of Wando River near Francis Marion National Forest in Berkeley County, South Carolina. © Tom Blagden, Jr.

Marsh and grasses at Guerin Creek, a tributary of the Wando River near Francis Marion National Forest in Berkeley County, South Carolina. © Tom Blagden, Jr.


Science shows that marshes reduce property losses.  

The Nature Conservancy worked with the insurance industry—including Lloyd’s and Risk Management Solutions—to use insurance risk models to show that coastal wetlands in the northeastern U.S. prevented $625 million in property damages from flooding during Hurricane Sandy. The study also showed that these same wetlands reduce annual storm damage by at least 15 percent. Together, we have also produced a report that shows that there are many cost-effective and sensible ways to finance natural infrastructure for coastal flood damage reduction and support the re-building of coastal resilience.

Less than 3 percent of funding currently goes to natural infrastructure as opposed to “grey” or “built” infrastructure. This is a coastal investment portfolio that should be re-balanced, especially when funds are made available for rebuilding after major storms, as has already happened because of the devastating hurricanes during the 2017 season..

GET TEXT UPDATES*