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Coral reefs provide $5.3 billion in flood protection on U.S. coast

A new study from UC Santa Cruz has revealed that flood protection provided by coral reefs is worth more than $1.8 billion per year in the United States alone. The research showed that losing one meter of reef height would impact 90 percent more property and increase damages by $5.3 billion.

In collaboration with experts at the U.S. Geological Survey, the researchers also determined that the country has 200 miles of extremely valuable reefs, mainly located in Hawaii and Florida. For flood protection alone, these reefs are worth more than $1.6 million per mile annually.

“Valuing the flood risk-reduction service of existing ecosystems is one step toward managing them as natural infrastructure,” said study lead author Borja Reguero. “This study provides new local information on how reefs protect communities at the building-block level, while maintaining a national focus for policy purposes.”

To create detailed estimates of the value of coral reef defenses along U.S. coastlines, the researchers combined computer models of storms and waves with engineering, ecological, mapping, social, and economic tools.

The team analyzed flood risk and assessed reef benefits along reef-lined coasts of Hawaii, Florida, Guam, American Samoa, Puerto Rico, the U.S. Virgin Islands, and the Commonwealth of the Northern Mariana Islands.

“These results identify how, where and when U.S. coral reefs provide the most significant coastal flood reduction benefits, helping state and territorial agencies better direct efforts to safeguard lives, avoid economic losses, and meet the goals of the U.S. Coral Reef Task Force to protect and preserve U.S. coral reefs,” said study co-author Curt Storlazzi.

The study authors calculated how much critical infrastructure – including hospitals, fire stations, roads, and power plants – coral reefs protect from coastal flooding. The researchers developed new computer models that can forecast flood damages with and without coral reefs all along the shoreline at very high resolution.

“Achieving this kind of definition required a complex modeling strategy to account for all the processes relevant in coral reef environments, which are significantly different to those driving flooding in other coastlines,” said Reguero. “The approach can also be applied to other ecosystems, and it now allows assessing the impacts of future changes in storms or sea level rise too.”

Coral reefs are threatened across the United States, but they can recover if resources are invested in their management and restoration, according to study co-author Michael Beck, who holds the AXA Chair in Coastal Resilience at UC Santa Cruz.

“This work quantifies the critical role of reefs in flood mitigation and provides the evidence needed to invest hazard management, disaster recovery, and insurance funds in these natural defenses,” said Beck. 

“We are glad to see that some of the key data and results from this work are already being used by the Federal Emergency Management Agency and the Nature Conservancy to inform reef restoration and new insurance options for reefs.”

The study is published in the journal Nature Sustainability.

By Chrissy Sexton, Staff Writer

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