In just two weeks, Hurricane Harvey devastated Houston, killing at least 70 people on the Gulf Coast, and on Wednesday, September 6, Hurricane Irma slammed into Puerto Rico after leaving the island of Barbuda “barely habitable,” according to the New York Times.
Many cities have built levees and other barriers to hold back the walls of water that hurricanes send surging onto land. However, constructing, maintaining and repairing this infrastructure can be expensive, and such barriers are not always effective at holding back the sea. But nature shows another way, according to Michael Beck, the lead marine scientist at the Nature Conservancy and an adjunct professor in the Department of Ocean Sciences at the University of California, Santa Cruz.
Beck is a coauthor of a new paper, published in the journal Nature’s Scientific Reports, which analyzed the economic value of coastal wetlands in flood prevention.
Beck and his colleagues found that wetlands on the northeast coast of the United States significantly reduced flooding from Hurricane Sandy in 2012 and avoided $625 million in damages.
The researchers worked with several major insurance companies, which have collected decades of data on the impact of weather-related disasters, to calculate the economic impact of coastal restoration.
Oceans Deeply spoke with Beck about the economic payoff of coastal restoration, why so much coastline is being lost and how green infrastructure can be financed to prevent future disasters.
Oceans Deeply: People often hear about how coastal wetlands, reefs and mangroves can reduce storm surges and protect coasts, but how does that actually work?
Michael Beck: Reefs work by breaking waves before they can reach the shore, so a lot of the wave energy is dissipated offshore. This is why you can see enormous waves breaking offshore with surfers on them and only ripples coming in to your hotel beach at the shore. Wetlands – mangroves and marshes – also break waves but more importantly they reduce storm surge by acting like barriers and baffles.
Oceans Deeply: Your study estimates that coastal wetlands reduced flood heights and saved $625 million in flood damage across 12 states affected by Hurricane Sandy. How did you come to that conclusion?
Beck: With support from the Lloyd’s of London Research Foundation, we worked with the insurance industry – with Risk Management Solutions (RMS) and Guy Carpenter and Co. – and used RMS risk models and property data to look at the damage caused to property by Hurricane Sandy along the northeast U.S. coastline. We wanted to know how much worse that damage might have been if there were no wetlands. So, in the insurance models, we took out every natural barrier along the coast and compared the two scenarios.
In addition, we looked at how storms impacted one area – Ocean County in New Jersey – over many years. We modeled 2,000 storms and found that, annually, wetlands reduce flood damage to property by 16 percent. This figure is likely to be relevant for many areas with temperate wetlands.
Oceans Deeply: This might seem like an obvious question, but why are we losing these ecosystems and natural barriers?
Beck: We’re losing most of it to development – everything from airports to aquaculture. In coastal cities, we’re clearing away these natural barriers and we’re building in the lowest-lying, most easily flooded areas. When the next storm comes, these areas will be the first and most heavily impacted. We need to be much more careful about building in these high-risk areas, particularly if we are building on top of our first line of defense to do it.
Oceans Deeply: In your view, how much more should we put toward the restoration of coastal wetlands? What is the goal?
Beck: We think that there needs to be 10 times more money going to coastal restoration. We need to be investing a great deal more money in it. Right now, after a storm, you have more than 97 percent of funding going to rebuilding gray infrastructure with very little going toward rebuilding our natural or green infrastructure. We need to rebalance this coastal funding portfolio.
Oceans Deeply: You have also looked into how much this kind of coastal restoration might itself cost – how will we pay for it?
Beck: There are many ways to fund this restoration and here are the top three based on our work.
First, insurers could lower insurance premiums in areas that are better protected by natural infrastructure, which would save communities money and incentivize them to restore their coastlines.
Second, we need to allocate more post-disaster spending toward natural infrastructure.
Third are tools like resilience bonds, which municipalities and others could use to invest in natural infrastructure to make areas less at risk to flooding, and so less financially risky as well.
In a report earlier this year on financing green infrastructure to reduce coastal flood damage, we concluded that one of the best ways to fund it is through public–private partnerships. Habitat restoration can be very cost effective, but it is not necessarily cheap, and so partnerships between the public and private sectors will be necessary to restore the natural infrastructure along our coasts.