The Value of U.S. Coral Reefs for Risk Reduction

By Pacific Coastal and Marine Science Center

Summary of the report, “Rigorously valuing the role of U.S. coral reefs in coastal hazard risk reduction”

Value of US Coral Reefs for Risk Reduction — Report summary pamphlet, Front and Back

Key Points:

The social and economic benefits provided by all U.S. reefs were rigorously assessed across more than 3,100 km (>1,900 miles) of coastline using hydrodynamic models coupled with census data.
Annually U.S. coral reefs provide flood protection benefits to more than 18,100 people and $1.8 billion in averted damages to property and economic activity.
With a 1-m loss in reef height, the 100-year floodplain would increase across the U.S. by 104 km², imperiling 51,000 more people and $5 billion in property and economic activity.
This study provides the most comprehensive set of flood risk maps across all US coral reef coastlines and the first ever national-scale quantification of flood protection benefits provided by coral reefs.

The degradation of coral reefs raises flood risks by increasing the exposure of coastal communities to storms.

The coastal protection benefits of coral reefs and other natural defenses are not usually assessed in the same rigorous, economic terms as artificial defenses such as seawalls, and therefore often not considered as an option in hazard management decisions. In this study, we combine engineering, ecologic, social, and economic data and tools to provide a rigorous valuation of the coastal protection benefits of U.S. coral reefs across Hawaii, Florida, Guam, American Samoa, Puerto Rico, the U.S. Virgin Islands, and the Commonwealth of the Northern Mariana Islands (CNMI).

Coral reefs act like submerged breakwaters by breaking waves and dissipating their energy offshore before they flood coastal properties and communities. This is an enormously valuable function. In 2017, Hurricanes Harvey, Irma and Maria alone caused over $265 billion in damage across the nation.

In this report, we demonstrate that coral reefs provide the U.S. with more than $1.8 billion dollars in flood protection benefits every year. They reduce direct flood damages to public and private property worth more than $800 million annually, and help avert other costs to lives and livelihoods worth an additional $1 billion. Coral reefs annually protect $184 million worth of buildings and economic activity in Puerto Rico, $675 million in Florida and $836 million in Hawaii.

These are not ‘back of the envelope’ numbers. Flood risk was assessed using sophisticated hydrodynamic models and more than 60 years of hourly wave data for U.S. coral reef coast lines – a total area of over 3,100 km (>1,900 miles) of shoreline. We developed flood risk maps projecting the extent and depth of flooding that would occur across a range of storms from the more commonly occurring to the catastrophic, with and without the top 1 m of coral reefs. These flood risk maps were combined with the latest information from the U.S. Census Bureau and the Federal Emergency Management Agency to identify people and properties at risk – and benefiting from the presence of coral reefs – in each location.

Rigorously valuing coral reef benefits in this way is a key step toward mobilizing resources to protect them. These maps and values can be used to inform:

storm response actions & recovery funding
coral reef conservation areas
public & private insurance incentives
benefit : cost analyses for reef restoration
the consideration of reefs as national infrastructure

Report Summary Pamphlets by Territory	Report Maps by Territory
American Samoa, Front and Back Florida, Front and Back Guam and the CNMI, Front and Back Hawaiʻi, Front and Back Puerto Rico, Front and Back US Virgin Islands, Front and Back	American Samoa Florida Guam and the CNMI Hawaiʻi Puerto Rico US Virgin Islands

Citation: Storlazzi, C.D., Reguero, B.G., Cole, A.D., Lowe, E., Shope, J.B., Gibbs, A.E., Nickel, B.A., McCall, R.T., van Dongeren, A.R., Beck, M.W., 2019, Rigorously valuing the role of U.S. coral reefs in coastal hazard risk reduction: U.S. Geological Survey Open-File Report 2019–1027, doi: 10.3133/ofr20191027

Reference: Reguero, B.G., Storlazzi, C.D., Gibbs, A.E., Shope, J.B., Cole, A.D., Cumming, K.A., and Beck, M.W., 2021, The value of U.S. coral reefs for flood risk reduction: Nature-Sustainability, 2398-9629, doi: 10.1038/s41893-021-00706-6

Watch our video below, to learn more.

Video Transcript

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The degradation of coastal habitats, particularly coral reefs, raises risks by increasing the exposure of coastal communities to flooding hazards during storms. The protective services of these natural defenses are not assessed in the same rigorous economic terms as artificial defenses, such as seawalls, and therefore often are not considered in decision-making. Here we combine engineering, ecologic, geospatial, social, and economic tools to provide a rigorous valuation of the coastal protection benefits of all U.S. coral reefs in the States of Hawaiʻi and Florida, the territories of Guam, American Samoa, Puerto Rico, and Virgin Islands, and the Commonwealth of the Northern Mariana Islands. We follow risk-based valuation approaches to map flood zones at 10-square-meter resolution along all 3,100+ kilometers of U.S. reef-lined shorelines for different storm probabilities to account for the effect of coral reefs in reducing coastal flooding. We quantify the coastal flood risk reduction benefits provided by coral reefs across storm return intervals using the latest information from the U.S. Census Bureau, Federal Emergency Management Agency, and Bureau of Economic Analysis to identify their annual expected benefits, a measure of the annual protection provided by coral reefs. The annual value of flood risk reduction provided by U.S. coral reefs is more than 18,000 lives and $1.805 billion in 2010 U.S. dollars. These data provide stakeholders and decision makers with spatially explicit, rigorous valuation of how, where, and when U.S. coral reefs provide critical coastal storm flood reduction benefits, and open up new opportunities to fund their protection and restoration. The overall goal is to ultimately reduce the risk to, and increase the resiliency of, U.S. coastal communities.View the audio-described version.