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

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
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Coral Reef Project
Quantifying Flood Risk and Reef Risk Reduction Benefits in Florida and Puerto Rico: The Consequences of Hurricane Damage, Long-term Degradation, and Restoration Opportunities
Data used to generate the maps of the U.S. states and territories, plus related data releases, are listed below.
Projected flooding extents and depths based on 10-, 50-, 100-, and 500-year wave-energy return periods, with and without coral reefs, for the States of Hawaii and Florida, the Territories of Guam, American Samoa, Puerto Rico, and the U.S. Virgin Islands,
Projected flooding extents and depths based on 10-, 50-, 100-, and 500-year wave-energy return periods for the State of Florida and the Commonwealth of Puerto Rico before and after Hurricanes Irma and Maria due to the storms' damage to the coral reefs
Projected flooding extents and depths based on 10-, 50-, 100-, and 500-year wave-energy return periods for the State of Florida, the Commonwealth of Puerto Rico, and the Territory of the U.S. Virgin Islands for current and potentially restored coral reefs
Model parameter input files to compare locations of coral reef restoration on different reef profiles to reduce coastal flooding
Cross-reef wave and water level data from coral reef environments
Database to model three-dimensional flow over coral reef spur-and-groove morphology
Model parameter input files to compare wave-averaged versus wave-resolving XBeach coastal flooding models for coral reef-lined coasts
HyCReWW database: A hybrid coral reef wave and water level metamodel
BEWARE database: A Bayesian-based system to assess wave-driven flooding hazards on coral reef-lined coasts
The pamphlets and maps accompany the U.S. Geological Survey Open-File Report shown below. Additional publications on related topics are also listed.
Rigorously valuing the role of U.S. coral reefs in coastal hazard risk reduction
Rigorously valuing the coastal hazard risks reduction provided by potential coral reef restoration in Florida and Puerto Rico
Rigorously valuing the impact of projected coral reef degradation on coastal hazard risk in Florida
Rigorously valuing the impact of Hurricanes Irma and Maria on coastal hazard risks in Florida and Puerto Rico
Coral reef restorations can be optimized to reduce coastal flooding hazards
The value of US coral reefs for flood risk reduction
Role of future reef growth on morphological response of coral reef islands to sea-level rise
The risk reduction benefits of the Mesoamerican Reef in Mexico
Coastal development and climate change are dramatically increasing the risks of flooding, erosion, and extreme weather events. Coral reefs and other coastal ecosystems act as natural defenses against coastal hazards, but their degradation increases risk to people and property. Environmental degradation, however, has rarely been quantified as a driver of coastal risk. In Quintana Roo, Mexico, a reg
Rigorously valuing the role of coral reefs in coastal protection: An example from Maui, Hawaii, U.S.A.
Below are news stories associated with this project.
Related Content
- Science
Below are other science projects associated with this project.
Coral Reef Project
Explore the fascinating undersea world of coral reefs. Learn how we map, monitor, and model coral reefs so we can better understand, protect, and preserve our Nation's reefs.Quantifying Flood Risk and Reef Risk Reduction Benefits in Florida and Puerto Rico: The Consequences of Hurricane Damage, Long-term Degradation, and Restoration Opportunities
Coastal flooding and erosion from extreme weather events affect thousands of vulnerable coastal communities; the impacts of coastal flooding are predicted to worsen during this century because of population growth and climate change. Hurricanes Irma and Maria in 2017 were particularly devasting to humans and natural communities. The coral reefs off the State of Florida and the Commonwealth of... - Data
Data used to generate the maps of the U.S. states and territories, plus related data releases, are listed below.
Projected flooding extents and depths based on 10-, 50-, 100-, and 500-year wave-energy return periods, with and without coral reefs, for the States of Hawaii and Florida, the Territories of Guam, American Samoa, Puerto Rico, and the U.S. Virgin Islands,
This data release provides flooding extent polygons (flood masks) and depth values (flood points) based on wave-driven total water levels for 22 locations within the States of Hawaii and Florida, the Territories of Guam, American Samoa, Puerto Rico, and the U.S. Virgin Islands, and the Commonwealth of the Northern Mariana Islands. For each of the 22 locations there are eight associated flood maskProjected flooding extents and depths based on 10-, 50-, 100-, and 500-year wave-energy return periods for the State of Florida and the Commonwealth of Puerto Rico before and after Hurricanes Irma and Maria due to the storms' damage to the coral reefs
This data release provides flooding extent polygons based on wave-driven total water levels for the coral lined coast of Florida and the Commonwealth of Puerto Rico. The wave and sea-level conditions were then propagated using the XBeach over 100-m spaced shore-normal transects modified to account for base and post-storm scenarios. In situ observations following hurricanes Irma and Maria were usedProjected flooding extents and depths based on 10-, 50-, 100-, and 500-year wave-energy return periods for the State of Florida, the Commonwealth of Puerto Rico, and the Territory of the U.S. Virgin Islands for current and potentially restored coral reefs
This data release provides flooding extent polygons based on wave-driven total water levels for the coral lined coasts of Florida, Puerto Rico, and the U.S. Virgin Islands. The locations of the restoration lines along and across shore were defined by the presence of continuous coral/hardbottom habitat of greater than 100 m alongshore length and proximity to the 3-m depth contour. The wave and seaModel parameter input files to compare locations of coral reef restoration on different reef profiles to reduce coastal flooding
This dataset consists of physics-based XBeach Non-hydrostatic hydrodynamic models input files used to study how coral reef restoration affects waves and wave-driven water levels over coral reefs, and the resulting wave-driven runup on the adjacent shoreline. Coral reefs are effective natural coastal flood barriers that protect adjacent communities. Coral degradation compromises the coastal protectCross-reef wave and water level data from coral reef environments
Coral reefs provide important protection for tropical coastlines against the impact of large waves and storm damage by energy dissipation through wave breaking and bottom friction. However, climate change and sea level rise have led to growing concern for how the hydrodynamics across these reefs will evolve and whether these changes will leave tropical coastlines more vulnerable to large wave evenDatabase to model three-dimensional flow over coral reef spur-and-groove morphology
This data set consists of physics-based Delft3D-FLOW and SWAN hydrodynamic models input files used to study the wave-induced 3D flow over spur-and-groove (SAG) formations. SAG are a common and impressive characteristic of coral reefs. They are composed of a series of submerged shore-normal coral ridges (spurs) separated by shore-normal patches of sediment (grooves) on the fore reef of coral reef eModel parameter input files to compare wave-averaged versus wave-resolving XBeach coastal flooding models for coral reef-lined coasts
This data release includes the XBeach input data files used to evaluate the importance of explicitly modeling sea-swell waves for runup. This was examined using a 2D XBeach short wave-averaged (surfbeat, XB-SB) and a wave-resolving (non-hydrostatic, XB-NH) model of Roi-Namur Island on Kwajalein Atoll in the Republic of Marshall Islands. Results show that explicitly modelling the sea-swell componenHyCReWW database: A hybrid coral reef wave and water level metamodel
We developed the HyCReWW metamodel to predict wave run-up under a wide range of coral reef morphometric and offshore forcing characteristics. Due to the complexity and high dimensionality of the problem, we assumed an idealized one-dimensional reef profile, characterized by seven primary parameters. XBeach Non-Hydrostatic was chosen to create the synthetic dataset and Radial Basis Functions implemBEWARE database: A Bayesian-based system to assess wave-driven flooding hazards on coral reef-lined coasts
A process-based wave-resolving hydrodynamic model (XBeach Non-Hydrostatic, XBNH) was used to create a large synthetic database for use in a Bayesian Estimator for Wave Attack in Reef Environments (BEWARE), relating incident hydrodynamics and coral reef geomorphology to coastal flooding hazards on reef-lined coasts. Building on previous work, BEWARE improves system understanding of reef hydrodynami - Multimedia
- Publications
The pamphlets and maps accompany the U.S. Geological Survey Open-File Report shown below. Additional publications on related topics are also listed.
Rigorously valuing the role of U.S. coral reefs in coastal hazard risk reduction
The degradation of coastal habitats, particularly coral reefs, raises risks by increasing the exposure of coastal communities to flooding hazards. 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, geospatialAuthorsCurt D. Storlazzi, Borja G. Reguero, Aaron Cole, Erik Lowe, James B. Shope, Ann E. Gibbs, Barry A. Nickel, Robert T. McCall, Ap R. van Dongeren, Michael W. BeckRigorously valuing the coastal hazard risks reduction provided by potential coral reef restoration in Florida and Puerto Rico
The restoration of coastal habitats, particularly coral reefs, can reduce risks by decreasing the exposure of coastal communities to flooding hazards. In the United States, the protective services provided by coral reefs were recently assessed in social and economic terms, with the annual protection provided by U.S. coral reefs off the coasts of the State of Florida and the Commonwealth of PuertoAuthorsCurt D. Storlazzi, Borja G. Reguero, Kristen A. Cumming, Aaron Cole, James B. Shope, Camila Gaido L., T. Shay Viehman, Barry A. Nickel, Michael W. BeckRigorously valuing the impact of projected coral reef degradation on coastal hazard risk in Florida
The degradation of coastal habitats, particularly coral reefs, raises risks by increasing the exposure of coastal communities to flooding hazards. In the United States, the physical protective services provided by coral reefs were recently assessed, in social and economic terms, with the annual protection provided by U.S. coral reefs off the coast of the State of Florida estimated to be more thanAuthorsCurt D. Storlazzi, Borja G. Reguero, Kimberly K. Yates, Kristen A. Cumming, Aaron Cole, James B. Shope, Camila Gaido L., David G. Zawada, Stephanie R. Arsenault, Zachery W. Fehr, Barry A. Nickel, Michael W. BeckRigorously valuing the impact of Hurricanes Irma and Maria on coastal hazard risks in Florida and Puerto Rico
The degradation of coastal habitats, particularly coral reefs, raises risks by increasing the exposure of coastal communities to flooding hazards. In the United States, the physical protective services provided by coral reefs were recently assessed in social and economic terms, with the annual protection provided by U.S. coral reefs off the coasts of the State of Florida and the Commonwealth of PuAuthorsCurt D. Storlazzi, Borja G. Reguero, T. Shay Viehman, Kristen A. Cumming, Aaron Cole, James B. Shope, Sarah H. Groves, Camila Gaido L., Barry A. Nickel, Michael W. BeckCoral reef restorations can be optimized to reduce coastal flooding hazards
Coral reefs are effective natural coastal flood barriers that protect adjacent communities. Coral degradation compromises the coastal protection value of reefs while also reducing their other ecosystem services, making them a target for restoration. Here we provide a physics-based evaluation of how coral restoration can reduce coastal flooding for various types of reefs. Wave-driven flooding reducAuthorsFloortje Roelvink, Curt Storlazzi, Ap van Dongeren, Stuart PearsonThe value of US coral reefs for flood risk reduction
Habitats, such as coral reefs, can mitigate increasing flood damages through coastal protection services. We provide a fine-scale, national valuation of the flood risk reduction benefits of coral habitats to people, property, economies and infrastructure. Across 3,100 km of US coastline, the top-most 1 m of coral reefs prevents the 100-yr flood from growing by 23% (113 km2), avoiding flooding to 5AuthorsBorja G. Reguero, Curt Storlazzi, Ann E. Gibbs, James B. Shope, Aaron Cole, Kristen A. Cumming, Mike BeckRole of future reef growth on morphological response of coral reef islands to sea-level rise
Coral reefs are widely recognised for providing a natural breakwater effect that modulates erosion and flooding hazards on low‐lying sedimentary reef islands. Increased water depth across reef platforms due sea‐level rise (SLR) can compromise this breakwater effect and enhance island exposure to these hazards, but reef accretion in response to SLR may positively contribute to island resilience. MoAuthorsGerd Masselink, Robert T. McCall, Eddie Beetham, Paul Kench, Curt StorlazziThe risk reduction benefits of the Mesoamerican Reef in Mexico
Coastal development and climate change are dramatically increasing the risks of flooding, erosion, and extreme weather events. Coral reefs and other coastal ecosystems act as natural defenses against coastal hazards, but their degradation increases risk to people and property. Environmental degradation, however, has rarely been quantified as a driver of coastal risk. In Quintana Roo, Mexico, a reg
AuthorsBorja G. Reguero, Fernando Secaira, Alexandra Toimil, Mireille Escudero, Pedro Diaz-Simal, Michael W. Beck, Rodolfo Silva, Curt D. Storlazzi, Iñigo LosadaRigorously valuing the role of coral reefs in coastal protection: An example from Maui, Hawaii, U.S.A.
The degradation of coastal habitats, particularly coral reefs, raises risks by exposing communities to flooding hazards. 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 not considered in decision-making. Here we present a new methodology that combines economic, ecological, and enginAuthorsCurt D. Storlazzi, Borja G. Reguero, Erik Lowe, James B. Shope, Ann E. Gibbs, Mike Beck, Barry A. Nickel - News
Below are news stories associated with this project.