When flooding strikes, it can unleash a deluge of money as well as water. Billions of dollars flow to places soaked by hurricane-driven storm surges or massive rainstorms
Some of that money could go toward nature-based infrastructure that reduces future threats while also giving ecosystems a boost. But for such “green” solutions to beat out the default response of concrete and rock walls, it’s not enough to just tout the benefits. Proponents need to show these approaches also make financial sense before agencies such as the U.S. Army Corps of Engineers will open their wallets.
Now, scientists working in Florida and Puerto Rico have done just that. A new study in Science Advances shows that restoring reefs there could reduce future damages by hundreds of millions of dollars—with more than 200 kilometers of reef crossing the threshold where economic benefits outweigh the costs.
“Most hazard mitigation and disaster-recovery funding supports more artificial infrastructure such as seawalls that degrade nature. By valuing the benefits of natural infrastructure, we level the playing field and open major new funding opportunities for reef restoration,” said Michael Beck, head of the University of California Santa Cruz-based Center for Coastal Climate Resilience, which conducted the new research in tandem with scientists at the U.S. Geological Survey and the National Oceanic and Atmospheric Administration.
Interest in finding more natural ways to boost coastal protection was spurred in the Caribbean partly by destruction from the 2017 double-blow of hurricanes Irma and Maria. Those disasters opened the door to around $10 billion in coastal flood prevention projects. But to qualify for federal funding to reduce damage from future storms, a project needs an analysis showing that it will save more money than it will cost. That had never been done for natural alternatives to artificial breakwaters and bulkheads, the scientists write.
They set out to do just that for what they call “hybrid” reefs—artificial foundations topped with live coral. Using detailed maps of more than 1000 kilometers of coastline in Florida and Puerto Rico, along with models showing how flood waters would move across the landscape with and without these reefs, the scientists built a house-by-house picture of flood damage in different scenarios.
Reefs have long been recognized as natural storm and wave barriers. It’s evident to anyone who has watched huge waves break on the outside of a reef, while the inner waters stay calm. The new analysis showed that rebuilding reefs along all that coastline could shrink the amount of land inundated by a major hurricane—flooding that would occur roughly once every century—by nearly 20 square kilometers. When accounting for storms of various sizes, each year the reefs would, on average, extend flood protection to more than 3,000 people and reduce damage by $180 million for structures and another $210 million in economic activity.
In many places, the economic benefits didn’t exceed the cost of building the reefs—estimated at $3 million per kilometer. But it was a net gain in more than 200 kilometers of coastline where people and infrastructure are concentrated. Some of the biggest beneficiaries live in development hotspots in southern Florida – Palm Beach, Broward and Miami-Dade counties.
The model enables people to “measure when and how cost effective it is to adapt” with these reefs, said Borja Reguero, a UC Santa Cruz scientist involved in the research.
And the benefit isn’t just for the beachfront mansions of Palm Beach millionaires. The scientists found that homes right along beaches would often still get flooded. It was the people living just a short distance back from the beach who would be out of reach of the waves. Since property values and wealth often track with proximity to the beach, the scientists found that compared to the overall population of an area, the reefs delivered more of a benefit to the poor (256%), elderly (261%) and people of color (239%).
There are still potential downfalls for such an approach. As climate change advances, underwater heatwaves have devastated Caribbean corals, raising questions about the survival of coral on these new reefs.
But this research could serve as a model for how to help unlock disaster funding for natural infrastructure well beyond the shores of Florida, the scientists note. It could also be used by people interested in building dunes, marshes, mangrove forests or oyster reefs to help hold back the water with something besides more concrete.
Storlazzi, et. al. “Hybrid coral reef restoration can be a cost-effective nature-based solution to provide protection to vulnerable coastal populations.” Science Advances. Jan. 15, 2025.
Image: Lauren Toth/USGS
