We are combining ocean, engineering, ecologic, social, and economic modeling to provide a high-resolution, rigorous, spatially-explicit valuation of the coastal flood protection benefits provided by coral reefs and the cost effectiveness of reef restoration for enhancing those benefits.
The Problem
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 owing to population growth and climate change. There is an urgent need to develop better risk reduction and adaptation strategies to reduce coastal flooding and associated hazards. There is growing national recognition of the role of natural and nature-based solutions to address coastal risks. The biggest limitation to advancing the use of natural defenses in coastal management, however, is the lack of quantitative assessments of their engineering performance and economic benefits. Coral reefs, in particular, can substantially reduce coastal flooding and erosion by dissipating as much as 97 percent of incident wave energy. Reefs function like low-crested breakwaters, with hydrodynamic behavior well characterized by coastal engineering models. Indeed, the need for approaches that use state-of-the-art hydrodynamic and economic models to quantify risk reduction in monetary terms has been widely acknowledged and, thus far, unaddressed, particularly at regional scales. There are currently no comprehensive, high-resolution maps of the benefits or cost effectiveness of coral reef restoration for coastal flood risk reduction. Without this information, it is not possible for Federal, State, Territorial, and local governments and communities to include coral reef restoration in flood recovery and mitigation efforts.
Our Approach
We are combining hydrodynamic, coastal engineering, geospatial, social, and economic modeling to provide a high-resolution, rigorous, spatially explicit valuation of the coastal flood protection benefits provided by coral reefs at present across, and the cost effectiveness of reef restoration for enhancing those benefits. Our risk-based methods follow probabilistic risk assessment approaches used by the insurance industry and by FEMA and NOAA for the quantification of baseline risk and risk-reduction measures. We are assessing the benefits provided by reefs under present conditions and for different coral reef restoration scenarios. The restoration scenarios cover the range of risk reduction effects that restoration projects could provide, and therefore can pinpoint sites where restoration will be most beneficial and/or cost-effective. We are calculating spatially explicit values of the cost effectiveness of coral reef restoration and making them available in maps through a widely used, web-based, interactive, online decision-support tool.
For more information, see:
“The Value of U.S. Coral Reefs for Risk Reduction” and
Read the featured news article in Frontiers, “Coral reef restorations can be optimized to reduce flood risk.”
Please also see the associated efforts on the Coral Reef Ecosystem Studies (CREST) Project website:
Learn more about our related studies.
Quantifying Flood Risk and Reef Risk Reduction Benefits in Florida and Puerto Rico: The Consequences of Hurricane Damage, Long-term Degradation, and Restoration Opportunities
The Value of U.S. Coral Reefs for Risk Reduction
Summary of the report, “Rigorously valuing the role of U.S. coral reefs in coastal hazard risk reduction”
Coral Reef Ecosystem Studies (CREST)
Coral Reef Seafloor Erosion and Coastal Hazards
Below are data or web applications associated with this project.
Model parameter input files to compare the influence of channels in fringing coral reefs on alongshore variations in wave-driven runup along the shoreline
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
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,
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
Below are publications associated with this project.
A numerical study of geomorphic and oceanographic controls on wave-driven runup on fringing reefs with shore-normal channels
Action plan for restoration of coral reef coastal protection services: Case study example and workbook
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
Rebounds, regresses, and recovery: A 15-year study of the coral reef community at Pila‘a, Kaua‘i after decades of natural and anthropogenic stress events
Wave-driven flood-forecasting on reef-lined coasts early warning system (WaveFoRCE)
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 U.S. coral reefs in coastal hazard risk reduction
Below are news stories associated with this project.
- Overview
We are combining ocean, engineering, ecologic, social, and economic modeling to provide a high-resolution, rigorous, spatially-explicit valuation of the coastal flood protection benefits provided by coral reefs and the cost effectiveness of reef restoration for enhancing those benefits.
The Problem
Waikīkī from atop Diamond Head. Photo credit: Zetong Li on Unsplash 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 owing to population growth and climate change. There is an urgent need to develop better risk reduction and adaptation strategies to reduce coastal flooding and associated hazards. There is growing national recognition of the role of natural and nature-based solutions to address coastal risks. The biggest limitation to advancing the use of natural defenses in coastal management, however, is the lack of quantitative assessments of their engineering performance and economic benefits. Coral reefs, in particular, can substantially reduce coastal flooding and erosion by dissipating as much as 97 percent of incident wave energy. Reefs function like low-crested breakwaters, with hydrodynamic behavior well characterized by coastal engineering models. Indeed, the need for approaches that use state-of-the-art hydrodynamic and economic models to quantify risk reduction in monetary terms has been widely acknowledged and, thus far, unaddressed, particularly at regional scales. There are currently no comprehensive, high-resolution maps of the benefits or cost effectiveness of coral reef restoration for coastal flood risk reduction. Without this information, it is not possible for Federal, State, Territorial, and local governments and communities to include coral reef restoration in flood recovery and mitigation efforts.
Our Approach
Map showing the simulated flooding for a 100-year storm event with (blue) and without (red) coral reefs in San Juan, Puerto Rico. The red area thus represents the area protected by coral reefs. We are combining hydrodynamic, coastal engineering, geospatial, social, and economic modeling to provide a high-resolution, rigorous, spatially explicit valuation of the coastal flood protection benefits provided by coral reefs at present across, and the cost effectiveness of reef restoration for enhancing those benefits. Our risk-based methods follow probabilistic risk assessment approaches used by the insurance industry and by FEMA and NOAA for the quantification of baseline risk and risk-reduction measures. We are assessing the benefits provided by reefs under present conditions and for different coral reef restoration scenarios. The restoration scenarios cover the range of risk reduction effects that restoration projects could provide, and therefore can pinpoint sites where restoration will be most beneficial and/or cost-effective. We are calculating spatially explicit values of the cost effectiveness of coral reef restoration and making them available in maps through a widely used, web-based, interactive, online decision-support tool.
Map displaying the distribution of total economic losses (direct building damages and indirect economic disruption) in the U.S. that are prevented from flooding by coral reefs annually. In total, the annual coastal flooding risk reduction benefits provided by U.S. coral reefs exceed $1.8 billion. For more information, see:
“The Value of U.S. Coral Reefs for Risk Reduction” and
Read the featured news article in Frontiers, “Coral reef restorations can be optimized to reduce flood risk.”
Please also see the associated efforts on the Coral Reef Ecosystem Studies (CREST) Project website:
- Science
Learn more about our related studies.
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...The Value of U.S. Coral Reefs for Risk Reduction
Summary of the report, “Rigorously valuing the role of U.S. coral reefs in coastal hazard risk reduction”
Coral Reef Ecosystem Studies (CREST)
The specific objectives of this project are to identify and describe the processes that are important in determining rates of coral-reef construction. How quickly the skeletons of calcifying organisms accumulate to form massive barrier-reef structure is determined by processes of both construction (how fast organisms grow and reproduce) and destruction (how fast reefs break down by mechanical...Coral Reef Seafloor Erosion and Coastal Hazards
Synchronized field work focused on geochemistry, geology, and metabolic processes overlaid on a habitat map of an entire reef to produce a synoptic overview of reef processes that contribute to carbonate precipitation and dissolution. - Data
Below are data or web applications associated with this project.
Model parameter input files to compare the influence of channels in fringing coral reefs on alongshore variations in wave-driven runup along the shoreline
An extensive set of physics-based XBeach Non-hydrostatic hydrodynamic model simulations (with input files here included) were used to evaluate the influence of shore-normal reef channels on flooding along fringing reef-lined coasts, specifically during extreme wave conditions when the risk for coastal flooding and the resulting impact to coastal communities is greatest. These input files accompanyProjected 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 componenProjected 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 maskHyCReWW 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
Below are publications associated with this project.
Filter Total Items: 13A numerical study of geomorphic and oceanographic controls on wave-driven runup on fringing reefs with shore-normal channels
Many populated, tropical coastlines fronted by fringing coral reefs are exposed to wave-driven marine flooding that is exacerbated by sea-level rise. Most fringing coral reef are not alongshore uniform, but bisected by shore-normal channels; however, little is known about the influence of such channels on alongshore variations on runup and flooding of the adjacent coastline. We con-ducted a parameAuthorsCurt D. Storlazzi, Annouk Rey, Ap van DongerenAction plan for restoration of coral reef coastal protection services: Case study example and workbook
This report was prepared by the U.S. Environmental Protection Agency (USEPA), Office of Research and Development, as part of the Air, Climate and Energy (ACE) research program, with support from Tetra Tech, Inc., and in collaboration with the National Oceanic and Atmospheric Administration, the U.S. Geological Survey, and The Nature Conservancy. The ACE research program provides scientific informaAuthorsCatherine A. Courtney, Jordon M. West, Curt Storlazzi, T. Shay Viehman, Richard Czaplinski, Erin Hague, Elizabeth C. ShaverRigorously 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. BeckRebounds, regresses, and recovery: A 15-year study of the coral reef community at Pila‘a, Kaua‘i after decades of natural and anthropogenic stress events
Pila‘a reef on the north shore of Kaua‘i, Hawai‘i was subjected to a major flood event in 2001 that deposited extensive sediment on the reef flat, resulting in high coral mortality. To document potential recovery, this study replicated benthic and sediment surveys conducted immediately following the event and 15 years later. Coral cores were analyzed to determine coral growth rates and density. OuAuthorsKu'ulei S. Rodgers, A. Richards Dona, Y. O. Stender, A. O. Tsang, J. H. J. Han, Rebecca Weible, Nancy G. Prouty, Curt D. Storlazzi, Andrew M. GrahamWave-driven flood-forecasting on reef-lined coasts early warning system (WaveFoRCE)
Increasing the resilience of coastal communities while decreasing the risk to them are key to the continued inhabitance and sustainability of these areas. Low-lying coral reef-lined islands are experiencing storm wave-driven flood events that currently strike with little to no warning. These events are occurring more frequently and with increasing severity. There is a need along the world’s coralAuthorsWilliam Skirving, Curt Storlazzi, Emily A SmailCoral 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 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. Beck - News
Below are news stories associated with this project.