U.S. Department of the Interior

U.S. Geological Survey

Open-File Report 2019–1027

Rigorously Valuing the Role of U.S. Coral Reefs in 

Coastal Hazard Risk Reduction

Prepared in cooperation with the University of California Santa Cruz and The Nature Conservancy
Cover. Photograph of waves breaking and dissipating their energy on the coral reefs off Waikīkī and Honolulu, O‘ahu, Hawai‘i, demonstrating

 the coastal protection provided by these ecosystems. Photograph by Zetong Li on Unsplash.
Rigorously Valuing the Role of U.S. Coral Reefs 

in Coastal Hazard Risk Reduction

By Curt D. Storlazzi, Borja G. Reguero, Aaron D. Cole, Erik Lowe, James B. Shope, 

Ann E. Gibbs, Barry A. Nickel, Robert T. McCall, Ap R. van Dongeren, and 

Michael W. Beck

Prepared in cooperation with the University of California Santa Cruz and 

The Nature Conservancy

Open-File Report 2019–1027

U.S. Department of the Interior

U.S. Geological Survey
U.S. Department of the Interior

DAVID BERNHARDT, Acting Secretary

U.S. Geological Survey

James F. Reilly II, Director

U.S. Geological Survey, Reston, Virginia: 2019

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Suggested 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., and 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, 42 p., https://doi.org/10.3133/ofr20191027.

ISSN 2331-1258 (online)
iii

Contents

Abstract...........................................................................................................................................................1

Introduction.....................................................................................................................................................1

Methodology...................................................................................................................................................3

Projecting the Coastal Hazards..........................................................................................................4

Evaluating the Role of Coral Reefs in Coastal Protection ..............................................................4

Quantifying the Social and Economic Value of Coral Reef Protection ........................................6

Uncertainties, Limitations, and Assumptions.................................................................................13

Results ...........................................................................................................................................................14

Flooding Extents..................................................................................................................................14

Societal Impacts .................................................................................................................................14

Economic Impacts ..............................................................................................................................14

Critical Infrastructure.........................................................................................................................14

Evaluating Additional Potential Scenarios ..............................................................................................22

Conclusions...................................................................................................................................................22

Acknowledgments.......................................................................................................................................22

References Cited..........................................................................................................................................22

Additional Digital Information....................................................................................................................28

Appendix 1. SWAN Model Settings ..........................................................................................................30

Appendix 2. SWAN Model Grid Information............................................................................................31

Appendix 3. Benthic Habitat and Shoreline Datasets ..........................................................................32

Appendix 4. Cross-shore XBeach Transects ..........................................................................................33

Appendix 5. Bathymetric and Topographic Datasets ...........................................................................34

Appendix 6. XBeach Model Settings........................................................................................................35

Appendix 7. Societal Impacts by Demographics....................................................................................36

Appendix 8. Economic Impacts by Building Structure Type.................................................................38

Appendix 9. Economic Impact Caused by Building Damage................................................................42
iv

Figures

1. Map showing the location of the study areas .........................................................................2

2. Schematic drawing that shows the methodology used to evaluate the role of coral 

reefs in hazard risk reduction.....................................................................................................3

3. Maps showing output examples of the Simulating Waves Nearshore (SWAN) model 

and how one of the 500 wave conditions were dynamically downscaled to the 200-

meter grid scale offshore west Maui, Hawai‘i.........................................................................4

4. Map showing the coral extent and coverage offshore Lahaina, Maui, Hawai‘i................5

5. Plots of example topographic-bathymetric cross-sections and XBeach model wavedriven total water levels with and without the presence of coral reefs offshore west 

Maui, Hawai‘i.................................................................................................................................7

6. Map showing the 100-year floodplains with and without coral reefs on south Maui, 

Hawai‘i ............................................................................................................................................8

7. Maps showing example 10-meter resolution flood depth estimates for various storm 

recurrence intervals on south Maui, Hawai‘i...........................................................................9

8. Map showing the distribution of people protected by coral reefs from flooding for 

the 100-year storm on south Maui, Hawai‘i............................................................................11

9. Map showing the value of infrastructure protected by coral reefs from flooding for 

the 100-year storm on south Maui, Hawai‘i............................................................................12

10. Example plots showing damage curves both for “with” and “without” reef scenarios 

for Maui, Hawai‘i.........................................................................................................................13

Tables

1. Wave and current friction coefficients for different percentages of coral cover as 

determined from benthic habitat maps.................................................................................................... 6

2. Gross domestic product per person by island or region...................................................................10

3. Spatial extent, in square kilometers, protected by coral reefs from flooding for 

different return-interval storms by island or region............................................................................15

4. Spatial extent, in percentage of total coastal area per island or region, protected by coral 

reefs from flooding for different return-interval storms by island or region ................................15

5. Total number of people protected by coral reefs from flooding for different 

return-interval storms by island or region.............................................................................................16

6. Total number of buildings protected by coral reefs from flooding for different 

return-interval storms by island or region.............................................................................................16

7. Total value of all buildings protected by coral reefs from flooding for different 

return-interval storms by island or region.............................................................................................17

8. Total value of economic activity protected by coral reefs from flooding for different 

return-interval storms by island or region.............................................................................................17

9. Annual value of protection provided by coral reefs from flooding by island or region.............18

10. Total number of essential facilities protected by coral reefs from flooding for different 

return-interval storms by region..............................................................................................................19

11. Total number of lifeline utility systems protected by coral reefs from flooding for different 

return-interval storms by region..............................................................................................................20

12. Total transportation systems protected by coral reefs from flooding for different 

return-interval storms by region..............................................................................................................21

13. Critical infrastructure protected by coral reefs from flooding annually by region.....................21
v

Appendix Tables

7.1. Number of children protected by coral reefs from flooding for different 

 return-interval storms by island or region...........................................................................36

7.2. Number of senior citizens protected by coral reefs from flooding for different 

 return-interval storms by island or region...........................................................................36

7.3. Number of low-income individuals protected by coral reefs from flooding for

 different return-interval storms by island or region...........................................................37

7.4. Number of racial or ethnical minority individuals protected by coral reefs from 

 flooding for different return-interval storms by island or region.....................................37

8.1. Value of residential infrastructure protected by coral reefs from flooding for 

 different return-interval storms by island or region...........................................................38

8.2. Value of commercial infrastructure protected by coral reefs from flooding for 

 different return-interval storms by island or region...........................................................38

8.3. Value of industrial infrastructure protected by coral reefs from flooding for 

 different return-interval storms by island or region...........................................................39

8.4. Value of government infrastructure protected by coral reefs from flooding for 

 different return-interval storms by island or region...........................................................39

8.5. Value of educational infrastructure protected by coral reefs from flooding for

 different return-interval storms by island or region...........................................................40

8.6. Value of agricultural infrastructure protected by coral reefs from flooding for 

 different return-interval storms by island or region...........................................................40

8.7. Value of religious infrastructure protected by coral reefs from flooding for 

 different return-interval storms by island or region...........................................................41

9.1. Value of economic activity protected by coral reefs from flooding of residential 

 buildings for different return-interval storms by island or region ...................................42

9.2. Value of economic activity protected by coral reefs from flooding of commercial and 

 (or) industrial buildings for different return-interval storms by island or region..............42
vi

Conversion Factors

U.S. customary units to International System of Units

Multiply By To obtain

Length

inch (in.) 2.54 centimeter (cm)

inch (in.) 25.4 millimeter (mm)

foot (ft) 0.3048 meter (m)

mile (mi) 1.609 kilometer (km)

mile, nautical (nmi) 1.852 kilometer (km)

yard (yd) 0.9144 meter (m)

Area

square foot (ft2

) 929.0 square centimeter (cm2)

square foot (ft2

) 0.09290 square meter (m2)

square inch (in2

) 6.452 square centimeter (cm2)

section (640 acres or 1 square mile) 259.0 square hectometer (hm2

) 

square mile (mi2

) 259.0 hectare (ha)

square mile (mi2

) 2.590 square kilometer (km2) 

Abbreviations

DSAS Digital Shoreline Analysis System

EAB expected annual benefit

EAD expected annual damage

FFWCC Florida Fish and Wildlife Conservation Commission

FWRI Fish and Wildlife Research Institute

GOW Global Ocean Wave database

GDP gross domestic product

NGDC National Geophysical Data Center

NOAA National Oceanic and Atmospheric Administration

OIA Department of Interior’s Office of Insular Affairs

PacIOOS Pacific Island Ocean Observing System

PIBHMC Pacific Islands Benthic Habitat Mapping Center

SWAN Simulating Waves Nearshore spectral wave model

TIGER Topographically Integrated Geographic Encoding and Referencing 

USGS U.S. Geological Survey
Rigorously Valuing the Role of U.S. Coral Reefs in Coastal 

Hazard Risk Reduction

By Curt D. Storlazzi1, Borja G. Reguero2,3, Aaron D. Cole3, Erik Lowe3, James B. Shope3, Ann E. Gibbs1, Barry A. 

Nickel3

, Robert T. McCall4, Ap R. van Dongeren4, and Michael W. Beck2,3

Abstract

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, 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-squaremeter 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. Based on 

these results, the annual protection provided by U.S. coral reefs is 

estimated in:

• Avoided flooding to more than 18,180 people;

• Avoided direct flood damages of more than $825 million 

to more than 5,694 buildings;

• Avoided flooding to more than 33 critical infrastructure 

facilities, including essential facilities, utility systems, 

and transportation systems; and

• Avoided indirect damages of more than $699 million in 

economic activity of individuals and more than 

$272 million in avoided business interruption annually.

Thus, 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. The overall goal is to ultimately reduce the risk 

to, and increase the resiliency of, U.S. coastal communities.

Introduction

Coastal flooding and erosion from extreme weather events 

affect thousands of vulnerable coastal communities. Globally, 

insurers paid out more than $300 billion for coastal damages from 

storms in the 2000s (United Nations Office for Disaster Risk 

Reduction, 2011). The impacts of coastal flooding are predicted 

to worsen during this century owing to population growth and 

climate change (Hallegatte and others, 2013; Hinkel and others, 

2014; Reguero and others, 2018; Storlazzi and others, 2018). 

There is an urgent need to develop better risk reduction and 

adaptation strategies to reduce coastal flooding and associated 

hazards (Hinkel and others, 2014; National Research Council, 

2014). For example, the United States spends, on average, 

$500 million per year mitigating such coastal hazards (Federal 

Emergency Management Agency, 2016a). However, most of 

these funds are destined for the creation and maintenance of “gray 

infrastructure” (McCreless and Beck, 2016), such as seawalls, 

which have negative impacts on coastal ecosystems (Chapman 

and Underwood, 2011), and may not be cost effective for risk 

reduction when compared to natural (for example, coral or oyster 

reef restoration) and hybrid (for example, placing artificial new, 

hard substrate for natural recolonization) alternatives (Reguero and 

others, 2018). 

There is growing national recognition of the role of natural 

and nature-based solutions to address coastal risks (Wells and 

others, 2006; Cheong and others, 2013; Temmerman and others, 

2013; Costanza and others, 2014; Spalding and others, 2014; 

Sutton-Grier and others, 2015). The National Science and 

Technology Council highlights that “integrating ecosystem-service 

considerations into planning and decision making can help draw 

attention to the many critical contributions natural systems make 

toward improving the productivity, resilience, and livability of 

1

U.S. Geological Survey.

2

The Nature Conservancy.

3

University of California Santa Cruz.

4

Deltares.
2 Rigorously Valuing Coral Reef Coastal Protection

our Nation and communities” (National Science and Technology 

Council, 2015). 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 (Ferrario and others, 2014). Reefs function 

like low-crested breakwaters, with hydrodynamic behavior well 

characterized by coastal engineering models (Hoeke and others, 

2011; Taebi and Pattiaratchi, 2014; Quataert and others, 2015; 

Reguero and others, 2018). Yet the value of coral reefs for coastal 

defense is not fully recognized, and thus they continue to be 

lost—75 percent of the world’s coral reefs are rated as threatened 

(Hoegh-Guldberg and others, 2007; Mumby and others, 2007). 

The loss of reefs and their protection services will continue unless 

their economic value is accurately quantified and mainstreamed 

into policy and management decisions. Although there have been 

attempts to determine the influence of coral reefs in coastal hazard 

risk reduction (van Zanten and others, 2014; Yee and others,2014;

Pascal and others, 2016), these efforts made broad generalizations 

of coral coverage and reef morphology and their resulting influence 

on waves and wave-driven water levels that define the coastal 

hazard. Most of these studies provide index-based approaches to 

quantifying coastal flooding hazards rather than physics-based 

hydrodynamic model results that account for all of the interactions 

between the intrinsic properties of the reef (coral coverage and 

morphology) and extrinsic forcing (wave heights and periods). We 

have built on the work of Beck and others (2018) to build coupled 

hydrodynamic and economic models of reef benefits.

Our goal here is to develop and apply a process-based, highresolution, nonlinear model of coastal protection benefits from 

corals reefs, map these natural defense benefits at a resolution 

relevant to management scales, and provide a framework to 

rigorously value the people and property protected by coral reefs 

for a range of storm scenarios. These data were generated for all 

populated U.S. coral-reef-lined coasts, including 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 (fig. 1).

140°E 150°E 160°E 170°E 180° 170°W 160°W 150°W 140°W 130°W 120°W 110°W 100°W 90°W 80°W 70°W 60°W

60°N

50°N

40°N

30°N

20°N

10°N

0°

10°S

20°S

30°S 6,000 KILOMETERS

0 1,000 2,000 3,000 MILES

0 1,000 2,000 3,000 4,000 5,000

COMMONWEALTH

OF THE NORTHERN

MARIANA ISLANDS

GUAM

HAWAI‘I

FLORIDA

AMERICAN

SAMOA

PUERTO

RICO

U.S. VIRGIN

ISLANDS

NORTH

PACIFIC

OCEAN NORTH

ATLANTIC

OCEAN

SOUTH

PACIFIC

OCEAN

NORTH

AMERICA

SOUTH

AMERICA

AUSTRALIA

ASIA

Figure 1. Map showing the location of the study areas (outlined in red boxes).
Methodology 3

Methodology

Engineering, ecologic, social, and economic tools were 

combined to provide a quantitative valuation of the coastal 

protection benefits of coral reefs off populated coastlines of 

the United States. The goal of this effort was to identify how, 

where, and when coral reefs provide the most significant coastal 

flood reduction benefits in social and economic terms. This 

analysis follows a risk quantification valuation framework 

to estimate the risk reduction benefits from coral reefs and 

provide annual expected benefits in social and economic 

terms (Beck and Lange, 2016; Beck and others, 2018). This 

national mapping represents a unique and innovative effort to 

provide risk reduction values in rigorous quantitative terms, 

based on high-resolution flood modeling and state-of-the-art 

damage modeling with calculations based on approaches used 

by the Federal Emergency Management Agency. The methods 

follow a sequence of steps (fig. 2) that integrate physics-based 

hydrodynamic modeling, quantitative geospatial modeling, and 

social and economic analyses to quantify the hazard, the role of 

coral reefs in reducing flooding, and the averted economic and 

social consequences.

N

E W

S

Deep-water wave energy

Time (years)

Shallow-water wave energy

500 conditions

Flooding extents

Return intervals (years)

with reefs

without

reefs

Damage (percent)

Depth flooded (meters)

People

threatened

Return intervals (years)

with reefs

without

reefs

$$$

threatened

with reefs

without

reefs

Wave energy

Return intervals (years)

Area = Area

w/ reef

Area

w/o reef [ ]-[ ]

People = People

w/ reef Peoplew/o reef [ ]-[ ]

Built = Built

w/ reef

Built

w/o reef [ ]-[ ]

Cells = Cells

w/ reef

Cells

w/o reef [ ]-[ ]

Census

Hazus

Offshore wave data

100-m reef profiles

Map flood zones

HAZARDS: Downscaling waves to shore

ECOSYSTEM: Reef flood modeling

CONSEQUENCES: Assessing impact and benefits

Representative sea states

Storm intensity

Assess exposure

Propagate to nearshore

Effects of the reef

Economic damage

Reconstruct shallow

water wave data

Flood frequency

Assess risk

reduction benefits

A B C D

E F G H

I J K L

Figure 2. Schematic drawing that shows the methodology used to evaluate the role of coral reefs in hazard risk reduction. Each step 

is described in more detail in the methodology section.
4 Rigorously Valuing Coral Reef Coastal Protection

2

2

Projecting the Coastal Hazards

Sixty one years (1948–2008) of validated long-term, hourly 

hindcast deep-water wave data were extracted from the Global 

Ocean Wave (GOW) database (Reguero and others, 2012) for 

the populated, reef-lined coastal areas (fig. 2A). Following the 

methodology of Camus and others (2011), we propagated more 

than half a million hourly data on wave climate parameters to 

the nearshore shore using a hybrid downscaling approach. The 

offshore wave climate data (wave heights, wave periods, and 

wave directions) were synthesized into 500 combinations of 

sea states that best represented the range of conditions from the 

GOW database (fig. 2B). These selected sea states were then 

propagated to the coast using the physics-based Simulating Waves 

Nearshore (SWAN) spectral wave model (Booij and others, 1999; 

Ris and others, 1999; Delft University of Technology, 2016), 

which simulates wave transformations nearshore by solving the 

spectral action balance equation (fig. 2C). Previous studies have 

demonstrated that SWAN is capable of accurately simulating wave 

propagation around reef-lined islands (Hoeke and others, 2011; 

Taebi and Pattiaratchi, 2014; Storlazzi and others, 2015). Standard 

SWAN settings were used (for example, Hoeke and others, 2011; 

Storlazzi and others, 2015), except that the directional spectrum 

was refined to 5-degree bins to better handle refraction and 

diffraction in and amongst islands (appendix 1). 

In order to accurately model from the scale of the main island 

groups or large sections of coastline (order of tens of kilometers 

[km]) down to management scales (order of hundreds of meters 

[m]), a series of as many as three dynamically downscaled 

nested grids with square grid cells were used, depending on 

the region. The coarse SWAN grids provided spatially varying 

boundary conditions for finer scale SWAN grids (fig. 3B, C). 

The bathymetry for the SWAN grids was generated by grid-cell 

averaging of various bathymetric datasets (appendix 2). The 

propagated 500 shallow-water wave conditions from the finest 

SWAN grids were extracted at 100-m intervals along the coastline, 

at a water depth of 30 m (fig. 2D), and then reconstructed into the 

61-year hourly time series using multidimensional interpolation 

techniques (Camus and others, 2011). 

Evaluating the Role of Coral Reefs in Coastal 

Protection

Benthic habitat maps of coral cover percentage and 

spatial extent (appendix 3) were used to delineate the location 

of nearshore coral reefs and relative coral abundance along the 

reef-lined shorelines (fig. 4). Cross-shore transects were created 

every 100 m alongshore (appendix 4) using the Digital Shoreline 

Analysis System (DSAS) software version 4.3 in ArcGIS version 

10.3 (Thieler and others, 2009). Transects were cast in both 

landward and seaward directions using the smoothed baseline 

cast method with a 500-m smoothing distance, perpendicular to a 

baseline generated from coastlines digitized from U.S. Geological 

Survey 1:24,000 quadrangle maps and smoothed in ArcGIS using 

the polynomial approximation with exponential kernel algorithm 

and a 5,000-m smoothing tolerance (fig. 2E). Transects varied 

157° 156.5° 

21.0° 

20.7° 

156° 

160° 159° 158° 157° 156° 

22° 

21° 

1.0° 

0.9° 

156.58° 156.50° 156.42° 

20° 

19° 

155° 

7

0

Wave height (m)

A

B

C

Map area in B

Map area in C

EXPLANATION

Figure 3. Maps showing output examples of the Simulating Waves 

Nearshore (SWAN) model and how one of the 500 wave conditions were 

dynamically downscaled to the 200-meter (m) grid scale offshore west 

Maui, Hawai‘i. A. The 5-kilometer (km) resolution Hawaiian chain model. 

B. The 1-km resolution Maui Nui model embedded in the Hawaiian chain 

model. C. The 200-m resolution west Maui model embedded in the Maui 

Nui model. Colors indicate significant wave height, in meters.
Methodology 5

EXPLANATION

100-m XBeach 

 transects

Coral cover

0 to <10%

10 to <50%

50 to <90%

90 to 100%

0

0.5 KILOMETER

156°41’ 156°40’ 

20°53’ 

20°52’ 

0

0.1 0.2 0.3 0.4 0.5

0.1 0.2 0.3 0.4

MILE

Kahului

Area of

 map

Maui Kihei

Figure 4. Map showing the coral extent and coverage offshore Lahaina, Maui, Hawai‘i (Anderson, 2007). Colors indicate 

percentage (%) of coral coverage; gray lines show cross-shore transects at 100-meter (m) intervals.
6 Rigorously Valuing Coral Reef Coastal Protection

in absolute length in order to cross the −30 and +20 m elevation 

contours. The bathymetric (appendix 5) and coral coverage 

(appendix 3) data were extracted along these shore-normal 

transects at a horizontal grid-cell resolution of 1 m.

The nearshore wave time series (hourly data from 1948 to 

2008) were fit to a general extreme value distribution (Méndez 

and others, 2006; Menéndez and Woodworth, 2010) to obtain 

the significant wave heights associated with the 10-, 50-, 100-, 

and 500-year storm return periods (fig. 2F). Extreme water 

levels corresponding to the 10-, 50-, 100-, and 500-year storm 

return period for a given location were taken from the nearest 

National Oceanic and Atmospheric Administration tidal station, 

which include the effect of tropical cyclones (National Oceanic 

and Atmospheric Administration, 2017). The significant 

wave heights and peak periods associated with these returnvalue wave heights and sea levels were then propagated over 

the coral reefs along 100-m-spaced shore-normal transects 

(appendix 4) using the numerical model XBeach (Roelvink 

and others, 2009; Deltares, 2016), as demonstrated in figures 

2G and 4. XBeach solves for water-level variations up to the 

scale of long (infragravity) waves using the depth-averaged, 

nonlinear shallow water equations. The forcing is provided by a 

coupled wave action balance, in which the spatial and temporal 

variations of wave energy owing to the incident-period wave 

groups are solved. The radiation stress gradients derived from 

these variations result in a wave force that is included in the 

nonlinear shallow-water equations and generates long waves 

and water level setup within the model. Although XBeach was 

originally derived for mild-sloping sandy beaches, with some 

additional formulations, it has been applied in reef environments 

(Pomeroy and others, 2012; van Dongeren and others, 2013; 

Quataert and others, 2015; Storlazzi and others, 2018) and 

proved to accurately predict the key reef hydrodynamics. 

XBeach was run for 3,600 seconds in one-dimensional 

hydrostatic mode along the cross-shore transects, at a varying 

horizontal resolution between 10 m seawards and 1 m 

landwards (resolution varies depending on depth). Additional 

formulations were applied that incorporate the effect of higher 

bottom roughness on incident wave decay through the incident 

wave friction coefficient (f

w) and the current and infragravity 

wave friction coefficient (cf), as outlined by van Dongeren and 

others (2013). The friction induced by corals was parameterized 

based on the spatially varying coral coverage data and results 

from a meta-analysis of wave-breaking studies over various 

reef configurations and friction coefficients for the different 

coral coverages (for example, van Dongeren and others, 2013; 

Quataert and others, 2015). Coral coverage was assigned f

w and 

cf (table 1) over the spatial extent of the reef along the profile 

as defined from the benthic habitat maps (appendix 3). The 

XBeach model runs generally stabilized after 100–150 seconds 

and thus generated good statistics on waves and wave-driven 

water levels for more than 50 minutes (model parameters given 

in appendix 6). Although the application of a one-dimensional 

model neglects some of the dynamics that occur on natural 

reefs, such as lateral flow, it provides a conservative estimate 

for infragravity wave generation and wave runup, as the forcing 

Table 1. Wave and current friction coefficients for different 

percentages of coral cover as determined from benthic habitat maps.

Coral coverage,

in percent

Wave friction 

coefficient 

(f

w)

Current and infragravity wave 

friction coefficient

(cf)

None (sand) 0.10 0.01

0–10 0.15 0.07

10–50 0.30 0.10

50–90 0.45 0.13

90–100 0.60 0.15

is shore normal. Thus, the flooding is likely underrepresented 

around promontories where wave-energy convergence would 

cause increased wave-driven flooding that is not captured with 

one-dimensional models, and likely underrepresented in small 

embayments where diffraction would disperse wave energy and 

thus reduce wave-driven flooding. The use of one-dimensional 

modeling is warranted in this case because the SWAN wave 

direction output at the most nearshore grid cells that provides 

forcing to the XBeach models were predominantly near normal. 

Upon completion of the simulations, the total water levels 

(setup plus runup) at each grid cell along the profiles were then 

extracted to define the wave-driven flooding along each of the 

profiles (fig. 5).

The wave and sea level conditions were then propagated 

using the XBeach model over the same 100-m spaced shorenormal transects modified to account for the loss of the coral 

reef (fig. 2G). A loss of coral coverage and, thus, rugosity and 

frictional effects (for example, Quataert and others, 2015) was 

parameterized by setting the f

w and cf

 to that of sand (table 

1) per van Dongeren and others (2013). The loss of coral 

reef structure was parameterized by reducing the elevation 

(increasing the depth) of the shore-normal profile 1 m over the 

spatial extent of the reef along the profile based on observations 

of bathymetric change owing to reef loss by Sheppard and 

others (2005) and Yates and others (2017). Total water levels 

(setup plus runup) at each grid cell along the profiles were then 

extracted to define the wave-driven flooding along these profiles 

without the influence of the coral reefs (fig. 5). 

Quantifying the Social and Economic Value of 

Coral Reef Protection

Wave-driven total water levels for each of the four return 

intervals (fig. 2H) along the shore-normal transects were 

then interpolated between adjacent shore-normal transects to 

develop a flood extent layer (fig. 6) for both model runs, with 

and without coral reefs (fig. 2I). The flood extent polygons 

were built by creating a minimum-bounding polygon between 

neighboring flood points (points in space, with information on 

flood water depth, along each 100-m spaced transect). The flood 

points were interpolated to create a flood depth raster (fig. 7) 
Methodology 7

using natural neighbor interpolation and clipped by the extent 

of flooding polygon. For each flood-extent polygon, the cells 

flooded by wave-driven setup and runup for both scenarios were 

logged and areas computed (fig. 2J). The somewhat variable 

nature of the inland flooding extents (fig. 6) are caused by the 

interpolation between adjacent XBeach model profile crosssections spaced every 100-m alongshore. The cross-shore 

profiles intersect different bathymetries, coral reefs, and flood 

up and over different topographies and therefore the extents of 

inland flooding sometimes vary substantially from one profile 

to the next. For example, a transect with high coral cover and 

a steeper shoreface with higher terrestrial elevations that limit 

flood extent may be adjacent to a section of coast characterized 

by lower coral cover, a more gently sloping shoreface, and 

lower terrestrial elevations that would result in greater inland 

flooding than the neighboring transect. 

The resulting number of people threatened, damage, and 

economic impact were then computed using wave-driven flood 

extents and depths. The people and associated demographic 

attributes (race, income, and so on) impacted by wave-driven 

flooding were determined by cross-referencing the flooded cells 

with the U.S. Census Bureau’s (2016) TIGER/Line database, as 

20

10

0

−10

−20

−30

2.0

1.8

1.6

1.4

1.2

1.0

0.8

0.6

20

10

0

1.0

0.5

1.5

2.0

−10

−20

−30

0 500 1,000 1,205 1,210 1,215 1,220

Cross-shore distance (m) 

Profile with reef

Profile without reef Water level without reef

Water level with reef

Water level, in meters

1,500

0 200 400 600 800 1,000 710 715 720

2,000

Profile 3253

Profile 3042

EXPLANATION

Profile 3253 zoomed

Profile 3042 zoomed

A

C

B

D

Figure 5. Plots of example topographic-bathymetric cross-sections and XBeach model wave-driven total water 

levels, in meters (m), with and without the presence of coral reefs offshore west Maui, Hawai‘i. A. Cross-shore 

profile 3253 with a continuous fringing reef offshore. B. Zoomed-in view of profile 3253. C. Cross-shore profile 

3042 with patch reefs offshore. D. Zoomed-in view of profile 3042. The black line denotes bathymetry and the blue 

line the total water level (setup plus runup) with coral reefs; the green line denotes bathymetry and the red line 

the total water level without coral reefs.
8 Rigorously Valuing Coral Reef Coastal Protection

EXPLANATION

Area flooded

100-year storm return period, with reefs

100-year storm return period, without reefs

Reef and hardbottom

0

1 KILOMETER

Area of 

map

156°28' 156°27' 

20°46'

20°45'

20°44'

0

1 MILE

Kahului

Maui Kihei

Figure 6. Map showing the 100-year floodplains with and without coral reefs on south Maui, Hawai‘i. The blue regions denote the 

flooding extent from a 100-year storm with coral reefs present, and the red regions denote the additional flooding extent with 1 meter 

of coral reef loss (beyond the blue region). That is, the region protected by coral reefs from a 100-year storm is in the red band.
Methodology 9

156°27'20" 156°27'

20°44' 20°43'40"

156°27'20" 156°27'

20°44' 20°43'40"

0 0.25 0.50 MILE

0 0.25 0.50 KILOMETER

10-year return interval 50-year return interval

100-year return interval 500-year return interval

Flood depth

EXPLANATION

(meters)

10

0

A B

C D

Figure 7. Maps showing example 10-meter resolution flood depth estimates for various storm recurrence intervals on south Maui, 

Hawai‘i. A. 10-year storm. B. 50-year storm. C. 100-year storm. D. 500-year storm. Colors indicate flood-water depth, in meters, 

interpolated from adjacent XBeach model profile transects spaced every 100 meters along the coast. 
10 Rigorously Valuing Coral Reef Coastal Protection

shown in figure 8. These TIGER/Line values are based on the 

2010 census, and, thus, may not reflect current-day populations 

and demographics. The number of people flooded was calculated 

from the intersection between the flood-depth raster and people 

per unit area. The built infrastructure impacted by wave-driven 

flooding were determined by cross-referencing the flooded cells 

with the Federal Emergency Management Agency’s (2016b) 

flood hazard exposure data in the Hazus database (Scawthorn and 

others, 2006a, b). These Hazus values are based on 2010 data, and, 

thus, may not reflect current-day building values and distributions. 

For the territories with no flood hazard exposure data (Guam, 

American Samoa, and the Northern Mariana Islands), tsunami 

hazard exposure data were used instead. However, the tsunami 

exposure data in these territories have a resolution of 1 square 

kilometer (km2), whereas the flood hazard exposure data are at 

the census-block level (resolution of tens to hundreds of square 

meters). The extracted Hazus data original field names were 

changed, and the data projected into each respective Universal 

Transverse Mercator coordinate system (coordinate system from 

the transects belonging to that region). 

For each type of Hazus asset (COM1, COM2, IND1, 

IND2, and so on), a damage-degree raster was created using 

the damage functions found in Hazus (fig. 2K) for the different 

categories of infrastructure, following the methodology of 

Wood and others (2013). These damage functions translate 

flood-water depth to the degree of damage (percentage of 

damage to each type of building). The damage-degree raster 

was built from the flood-depth raster and every cell represents 

the degree (or percentage) of damage from flooding, with values 

ranging from 0.0 (no damage) to 1.0 (complete damage). Once 

the damage-degree rasters were built, the economic value of 

the damage (in dollars) was calculated for each asset as the 

building value per unit area multiplied by degree of damage, as 

shown in figure 9. Similarly, the number of flooded buildings 

result from the intersection between the flood-depth raster and 

buildings (and specific building types) per unit area, as shown 

in figure 9. Critical infrastructure in the flooded zones, obtained 

from the Hazus database, was also counted, if they were present 

in the flood zone. Finally, building damage, number of flooded 

buildings, and number of people flooded were summarized. The 

summary points were created as regularly 10-m spaced points 

within the union between all flood extents. 

The value of coral reefs in terms of coastal hazard risk 

reduction was then determined as the difference in people and 

infrastructure impacted by wave-driven flooding in the simulations 

including coral reefs from those without coral reefs (fig. 2L). 

The calculated damages were aggregated by infrastructure type 

and summarized into tables (see results section) for each return 

period. The types of infrastructure were aggregated based upon 

the general building stock categories in Hazus (residential, 

commercial, industrial, agricultural, religious, government, and 

education buildings). Damage was estimated by percentage and 

was weighted by the area of flooding at a given depth for a given 

census block. The composition of the general building stock 

within a given census block was assumed to be evenly distributed 

throughout the block. 

The summary tables provide damages for the different return 

periods and for each building stock type (appendix 8). A storm 

return period, Ti

, also known as a recurrence interval, is the inverse 

of the probability of occurring and an estimate of the likelihood 

of an event. For example, a return period of a flood of 100 years 

represents a probability of occurring in a given year of 1/100, or 

0.01. The damages associated with the probability of occurrence 

characterize risk for the two reef scenarios, with and without reefs. 

The expected annual damage (EAD) is the frequency-weighted 

sum of damages for the full range of possible damaging flood 

events and is a measure of what might be expected to occur in 

a given year. The EAD was calculated from each damage curve 

(with and without reefs; fig. 10) as

EAD = 1

2

1

Ti

− 1

Ti +1

⎛

⎝

⎜

⎞

⎠

⎟(Di + Di+1) i=1

n

 ∑ 

 

where Di represents the loss in the damage curve (fig. 2L) for the 

probability of 1/Ti, per Olsen and others (2015). The benefits were 

calculated as the difference in damages between the two scenarios: 

with and without reefs. The expected annual benefit (EAB), a 

measure of the annual protection of coral reefs, is calculated as

 EAB = EADwithout reefs− EADwith reefs

The economic impact of wave-driven coastal flooding, however, 

is not only the physical damage to structures themselves, but also 

to the disruption of peoples’ and businesses’ incomes and thus the 

contribution to the gross domestic product (GDP) of that housing 

and commercial/industrial infrastructure, respectively (Federal 

Emergency Management Agency, 2018). By multiplying the 

2010 average contribution to GDP per person (table 2; Bureau of 

Economic Analysis, 2018) by the number of people living in the 

regions protected by coral reefs, one can compute the economic 

activity protected for people not displaced by the loss of housing 

from coastal flooding. Similarly, by multiplying the 2010 average 

of 15.1 employees per business (U.S. Census Bureau, 2018) by 

the 2010 average contribution to GDP per person (table 2; Bureau 

of Economic Analysis, 2018) by the number of commercial and 

industrial buildings in the regions protected by coral reefs, one 

can compute the economic activity protected for businesses not 

impacted by the loss of infrastructure from coastal flooding. 

Because there are no data linking the people living in an area 

Table 2. Gross domestic product (GDP) per person by island or region. 

[Data from Bureau of Economic Analysis (2018)]

Location GDP

(in 2010 U.S. dollars)

American Samoa 10,353

Northern Mariana Islands 14,681

Guam 30,700

Florida 38,604

Hawaiʻi 49,418

Puerto Rico 26,436

Virgin Islands 40,043
Methodology 11

EXPLANATION

Area flooded

100-year storm return period, 

 with reefs

100-year storm return period, 

 without reefs

Population protected by coral reefs

0–50

50–100

100–200

200–300

300–400

400–500

500–600

600–700

700–800

Reef and hardbottom 800–900

156°28' 156°27'

20°46'

20°45'

20°44'

0

0 1 KILOMETER

1 MILE

Kahului

Kihei Maui

Area of

 map

Figure 8. Map showing the distribution of people protected by coral reefs from flooding for the 100-year storm on south Maui, Hawai‘i. 

Colors indicate the population density, based on U.S. Census Bureau’s TIGER/Line data, in the area protected by coral reefs.
12 Rigorously Valuing Coral Reef Coastal Protection

EXPLANATION

Area flooded Total infrastructure exposure (× $1,000)

0–1

1–5

5–10

10–20

20–30

30–40

40–60

60–80

80–100

100–165

100-year storm return period, 

 with reefs

100-year storm return period, 

 without reefs

Reef and hardbottom

156°28' 156°27'

20°46'

20°45'

20°44'

Kahului

Kihei Maui

0

0 1 KILOMETER

1 MILE

Area of

 map

Figure 9. Map showing the value of infrastructure, in thousands of 2010 U.S. dollars, protected by coral reefs from flooding for the 100-year 

storm on south Maui, Hawai‘i. Colors indicate the total value of infrastructure, based on Federal Emergency Management Agency’s Hazus 

data, in the area protected by coral reefs.
Methodology 13

0

4,000

6,000

8,000

10,000

12,000

10 50 100 500

Number of people

10 50 100 500

Storm return interval, in years Storm return interval, in years

 With reefs

EXPLANATION

 Without reefs

2,000

A B

0

100

200

300

400

500

Building value, in millions of dollars ($)

Figure 10. Example plots showing damage curves both for “with” and “without” reef scenarios for Maui, Hawai‘i. A. Number 

of people displaced by loss of housing from coastal flooding. B. Values of damage to buildings by coastal flooding. The gray 

region denotes the protection provided by coral reefs.

to where those people work, we assume here that the economic 

activity protected for people not displaced by the loss of housing 

from coastal flooding is independent from the economic activity 

protected for businesses not impacted by the loss of infrastructure 

from coastal flooding.

Uncertainties, Limitations, and Assumptions

Numerical model errors were estimated to be 

±50centimeters. This value is greater than the root-meansquare and absolute errors computed between model results and 

measurements (van Dongeren and others, 2013; Quataert and 

others, 2015) but was used in an effort to mitigate for the fact 

that the number of storms tested are few and the geographic 

scope is large compared to where measurements for validation 

are available. The vertical resolution of the Hazus depth-damage 

curves is 0.3 m. Uncertainties associated with the baseline digital 

elevation model varied based on input data; see references listed 

in appendix 5. Other limitations and assumptions pertaining to 

flood extents and the resulting computed social and economic 

consequences include

• The extreme value analysis for selecting storm 

return periods was stationary and did not include 

nonstationary effects, such as El Niño, in the selection 

of values. The fit of each time series had to be limited 

to a number of thresholds and could not be adapted 

iteratively. These thresholds were also different for 

each region, depending on the number of extremes to 

select (with a limit of at least 30 extreme values to fit 

the extreme value distribution).

• The model scheme used to define the extreme flood 

levels were a combination of the wave and surge 

conditions for certain storm probabilities and did not 

consider dependencies between both variables or the 

joint distribution of wave heights, wave periods, and 

surge levels. However, it is likely that large surges and 

waves occur simultaneously for large return periods.

• We did not consider tide levels, beyond those registered 

in the extreme values measured in the tidal gauges 

that were used to define the extreme sea level for each 

region.

• The modeling structure of one-dimensional cross-shore 

transects assumes shore-normal wave and flooding 

processes.

• The approach for assessing flood damages 

and the resulting benefits associated with each 

probability assumes that the probability of the extreme 

flooding conditions on the fore reef defines the 

probability of the flood zones and the resulting flood 

damages (thus, the 1-in-100-year total water level 

represents the 100-year damage). 
14 Rigorously Valuing Coral Reef Coastal Protection

• The most statistically accurate assessment of flood 

damages would require defining the statistical distribution 

of damages, instead of flood levels—for example, 

calculating the extreme economic damages. However, this 

requires the reconstruction of the runup time series and the 

calculation of spatial losses associated with each event, 

which is outside the scope of this work.

• Alternative ways to calculate these statistics of economic 

damages would imply taking larger simplifications and 

uncertainties in the modeling of flooding, which would 

likely affect the accuracy of the results.

• Flood depths and extents between cross-shore transects 

modeled are alongshore interpolations and are not exact 

representations of model output, as they did not consider 

topographic features between the transects.

• U.S. Census Bureau’s (2016) TIGER/Line data and Federal 

Emergency Management Agency’s (2016b) flood hazard 

exposure data in the Hazus database are based on the 2010 

census, and, thus, may not reflect current-day populations, 

demographics, building values, and distributions.

• The composition of the general building stock within a 

given census block was assumed to be evenly distributed 

throughout the block. 

• The 2010 average of 15.1 employees per business was 

uniformly applied to the number of commercial and 

industrial buildings to compute the economic activity 

protected for businesses not impacted by the loss of 

infrastructure from coastal flooding.

• The economic activity protected for people not displaced 

by the loss of housing from coastal flooding is independent 

from the economic activity protected for businesses not 

impacted by the loss of infrastructure from coastal flooding.

Results

Flooding Extents

This section summarizes the benefits provided by coral 

reefs for each region considered in the analysis for the four 

storm return periods. The benefits are expressed in terms 

of land surface, damage averted, and number and value of 

buildings or assets protected from coastal flooding. The 

benefits are calculated as the differences between the “with” 

and “without” reef scenarios. The expected annual benefit, in 

terms of area protected by U.S. coral reefs annually, is 82.9 km2

(32.0 square miles, mi2), or 4 percent of the coastal zone in the 

islands or regions studied in this report (tables 3 and 4).

Societal Impacts

The expected annual benefit, in terms of the number of 

people protected by U.S. coral reefs annually, is 18,180 people 

(table 5). The breakdown in benefits by demographics (children, 

senior citizens, low income, and minorities) is provided in 

appendix 7.

Economic Impacts

The expected annual benefit, in terms of the number 

of buildings protected by U.S. coral reefs annually, is 5,694 

(table 6). The breakdown in benefits by type of structure 

(residential, commercial, industrial, government, educational, 

agricultural, and religious) is provided in appendix 8. The total 

value of those buildings protected by U.S. coral reefs annually 

is $825,926,417 (table 7). The expected annual benefit, in 

terms of the value of economic activity provided by housing 

that is protected by U.S. coral reefs annually, is $699,214,729 

(appendix 9) and the value of economic activity provided by 

commercial and industrial buildings protected by U.S. coral 

reefs annually is $272,825,392 (appendix 9). In sum, the total 

expected annual benefit, in terms of the value of all coastal 

storm flooding protection (sum of tables 7 and 8) provided by 

U.S. coral reefs annually, is $1,805,511,877 (table 9).

Critical Infrastructure

The expected annual benefit, in terms of the number of 

essential facilities (hospitals, fire stations, police stations, 

schools, and emergency operation centers) protected in 

the United States by coral reefs annually, is 19 (table 10). 

The number of lifeline utility systems (water, wastewater, 

electrical, oil and gas, and communications) protected by coral 

reefs annually is 9 (table 11). The length of highway protected 

by coral reefs annually is 41.3 km (15.9 miles, mi) (table 12). 

Four transportation systems (ports and airports) are protected 

annually by coral reefs (tables 12 and 13).
Results 15

Table 3. Spatial extent, in square kilometers, protected by coral reefs from flooding for different return-interval storms by island or region.

Location Sublocation Storm return interval

10-year 50-year 100-year 500-year

American Samoa Tutuila 1.60 1.91 1.88 1.23

American Samoa Ofu and Olosega 0.20 0.22 0.24 0.26

American Samoa Taʻū 0.14 0.15 0.16 0.19

Northern Mariana Islands Saipan 0.34 0.55 0.57 1.11

Northern Mariana Islands Tinian 0.28 0.49 0.49 0.60

Guam Guam 0.88 1.11 1.26 1.28

Florida Peninsula 6.96 10.01 11.52 28.62

Florida Florida Keys 3.19 5.36 8.13 2.58

Hawaiʻi Island of Hawaiʻi 6.23 7.17 7.69 9.15

Hawaiʻi Maui 10.84 9.27 7.57 4.48

Hawaiʻi Lānaʻi 0.73 0.81 0.86 1.02

Hawaiʻi Molokaʻi 1.59 1.71 1.80 2.18

Hawaiʻi Kahoʻolawe 0.40 0.44 0.45 0.47

Hawaiʻi Oʻahu 11.08 9.71 9.52 9.00

Hawaiʻi Kauaʻi 2.60 3.85 4.32 5.89

Hawaiʻi Niʻihau 0.73 0.88 1.07 1.35

Puerto Rico Isla de Puerto Rico 22.71 26.11 29.57 37.74

Puerto Rico Isla de Culebra 0.29 0.40 0.62 0.77

Puerto Rico Isla de Vieques 0.75 1.26 1.39 1.75

Virgin Islands Saint Croix 2.17 2.75 3.01 3.34

Virgin Islands Saint John 0.14 0.22 0.31 0.27

Virgin Islands Saint Thomas 0.32 0.41 0.50 1.33

Table 4. Spatial extent, in percentage of total coastal area per island or region, protected by coral reefs from flooding for different 

return-interval storms by island or region.

[Total coastal area refers to land less than 1 kilometer inland and below 10 meters in elevation]

Location Sublocation Storm return interval

10-year 50-year 100-year 500-year

American Samoa Tutuila 8 9 9 6

American Samoa Ofu and Olosega 7 8 9 10

American Samoa Taʻū 4 5 5 6

Northern Mariana Islands Saipan 2 3 3 5

Northern Mariana Islands Tinian 2 4 4 5

Guam Guam 1 2 2 2

Florida Peninsula 3 4 5 12

Florida Florida Keys 1 2 3 1

Hawaiʻi Island of Hawaiʻi 3 4 4 5

Hawaiʻi Maui 14 12 10 6

Hawaiʻi Lānaʻi 4 4 4 5

Hawaiʻi Molokaʻi 3 3 3 4

Hawaiʻi Kahoʻolawe 4 5 5 5

Hawaiʻi Oʻahu 5 4 4 4

Hawaiʻi Kauaʻi 3 5 6 8

Hawaiʻi Niʻihau 2 2 2 3

Puerto Rico Isla de Puerto Rico 5 6 6 8

Puerto Rico Isla de Culebra 3 4 6 7

Puerto Rico Isla de Vieques 2 3 3 4

Virgin Islands Saint Croix 4 5 6 6

Virgin Islands Saint John 1 1 2 1

Virgin Islands Saint Thomas 2 2 3 7
16 Rigorously Valuing Coral Reef Coastal Protection

Table 5. Total number of people protected by coral reefs from flooding for different return-interval storms by island or region.

[–, no value determined]

Location Sublocation Storm return interval

10-year 50-year 100-year 500-year

American Samoa Tutuila 1,046 1,009 990 649

American Samoa Ofu and Olosega 6 8 9 12

American Samoa Taʻū 15 17 17 25

Northern Mariana Islands Saipan 704 878 560 1,580

Northern Mariana Islands Tinian 9 51 58 23

Guam Guam 197 156 198 312

Florida Peninsula 7,820 15,981 20,130 53,584

Florida Florida Keys 1,064 3,344 3,938 2,099

Hawaiʻi Island of Hawaiʻi 600 724 743 796

Hawaiʻi Maui 6,248 6,013 4,235 2,749

Hawaiʻi Lānaʻi 0 0 0 0

Hawaiʻi Molokaʻi 2 3 3 13

Hawaiʻi Kahoʻolawe – – – –

Hawaiʻi Oʻahu 5,586 5,637 3,957 3,553

Hawaiʻi Kauaʻi 193 189 313 355

Hawaiʻi Niʻihau 0 0 0 0

Puerto Rico Isla de Puerto Rico 6,840 12,424 17,609 35,279

Puerto Rico Isla de Culebra 17 32 39 90

Puerto Rico Isla de Vieques 1 1 1 1

Virgin Islands Saint Croix 482 699 914 429

Virgin Islands Saint John 6 8 25 8

Virgin Islands Saint Thomas 108 113 93 80

Table 6. Total number of buildings (of all infrastructure types) protected by coral reefs from flooding for different return-interval storms 

by island or region.

[–, no value determined]

Location Sublocation Storm return interval

10-year 50-year 100-year 500-year

American Samoa Tutuila 425 405 417 269

American Samoa Ofu and Olosega 1 2 2 2

American Samoa Taʻū 9 11 11 16

Northern Mariana Islands Saipan 53 72 58 167

Northern Mariana Islands Tinian 2 8 9 9

Guam Guam 58 45 59 84

Florida Peninsula 1,129 2,565 2,945 9,781 

Florida Florida Keys 537 1,703 1,985 1,099

Hawaiʻi Island of Hawaiʻi 280 325 335 356

Hawaiʻi Maui 1,914 1,791 1,232 853

Hawaiʻi Lānaʻi 0 0 0 1

Hawaiʻi Molokaʻi 1 2 3 9

Hawaiʻi Kahoʻolawe – – – –

Hawaiʻi Oʻahu 1,586 1,722 1,163 1,049

Hawaiʻi Kauaʻi 113 137 209 222

Hawaiʻi Niʻihau 0 0 0 0

Puerto Rico Isla de Puerto Rico 3,425 5,667 7,261 11,622

Puerto Rico Isla de Culebra 17 29 37 69

Puerto Rico Isla de Vieques 2 4 4 2

Virgin Islands Saint Croix 175 250 274 190

Virgin Islands Saint John 4 6 15 5

Virgin Islands Saint Thomas 27 26 24 22
Results 17

Table 7. Total value of all buildings (of all infrastructure types) protected by coral reefs from flooding for different return-interval 

storms by island or region.

[Values in 2010 U.S. dollars. –, no value determined]

Location Sublocation Storm return interval

10-year 50-year 100-year 500-year

American Samoa Tutuila 45,062,194 50,235,092 55,296,346 45,151,430

American Samoa Ofu and Olosega 133,904 190,098 256,618 343,816

American Samoa Taʻū 1,332,694 1,705,537 1,913,229 1,714,184

Northern Mariana Islands Saipan 8,440,917 13,510,503 14,037,252 33,267,181

Northern Mariana Islands Tinian 1,135,367 1,901,951 2,095,199 2,870,504

Guam Guam 12,523,985 10,845,848 14,307,264 21,479,597

Florida Peninsula 496,808,161 1,087,517,050 1,433,821,392 4,639,275,600

Florida Florida Keys 51,302,037 114,538,932 152,395,028 115,357,921

Hawaiʻi Island of Hawaiʻi 42,875,759 50,655,894 52,324,393 59,566,784

Hawaiʻi Maui 202,802,131 234,104,090 225,630,115 194,479,455

Hawaiʻi Lānaʻi 97,224 104,730 105,981 106,313

Hawaiʻi Molokaʻi 72,094 92,642 128,534 354,783

Hawaiʻi Kahoʻolawe – – – –

Hawaiʻi Oʻahu 368,841,786 353,116,245 340,006,994 314,872,587

Hawaiʻi Kauaʻi 10,080,787 14,529,798 18,675,364 23,309,226

Hawaiʻi Niʻihau 0 0 0 0

Puerto Rico Isla de Puerto Rico 107,237,273 195,128,049 277,282,495 514,413,849

Puerto Rico Isla de Culebra 232,754 498,925 693,718 1,439,420

Puerto Rico Isla de Vieques 175,922 126,877 148,189 207,562

Virgin Islands Saint Croix 30,521,477 50,437,724 63,035,367 57,335,990

Virgin Islands Saint John 852,151 1,489,952 3,965,600 1,880,331

Virgin Islands Saint Thomas 5,910,764 7,253,756 7,139,596 8,204,784

Table 8. Total value of economic activity protected by coral reefs from flooding for different return-interval storms by island or region.

[Values in 2010 U.S. dollars. –, no value determined]

Location Sublocation Storm return interval

10-year 50-year 100-year 500-year

American Samoa Tutuila 12,838,554 12,737,169 12,689,057 8,134,705

American Samoa Ofu and Olosega 70,720 100,464 108,116 140,024

American Samoa Taʻū 260,015 332,638 322,957 428,946

Northern Mariana Islands Saipan 14,048,119 18,498,753 12,628,264 35,093,069

Northern Mariana Islands Tinian 178,904 925,324 1,056,896 499,245

Guam Guam 18,836,690 13,142,572 17,730,626 24,400,493

Florida Peninsula 437,955,608 885,356,612 1,085,772,141 2,967,707,234

Florida Florida Keys 61,747,854 194,808,506 245,200,855 160,115,742

Hawaiʻi Island of Hawaiʻi 47,318,440 54,994,432 56,569,432 59,507,116

Hawaiʻi Maui 485,867,446 464,643,386 311,738,118 186,049,202

Hawaiʻi Lānaʻi 2,323 3,379 3,287 5,608

Hawaiʻi Molokaʻi 120,000 170,267 235,027 882,889

Hawaiʻi Kahoʻolawe – – – –

Hawaiʻi Oʻahu 354,961,794 352,609,166 246,048,630 223,615,374

Hawaiʻi Kauaʻi 11,600,021 10,698,418 16,910,505 19,878,382

Hawaiʻi Niʻihau 1,620 4,454 3,914 3,914

Puerto Rico Isla de Puerto Rico 186,767,291 342,346,484 488,469,977 976,771,828

Puerto Rico Isla de Culebra 458,726 842,063 1,043,991 2,373,679

Puerto Rico Isla de Vieques 17,019 19,333 28,346 31,696

Virgin Islands Saint Croix 36,075,541 57,303,999 69,385,281 32,195,508

Virgin Islands Saint John 511,379 801,300 2,743,726 792,042

Virgin Islands Saint Thomas 6,585,099 5,650,708 4,585,817 4,316,449
18 Rigorously Valuing Coral Reef Coastal Protection

Table 9. Annual value of protection provided by coral reefs from flooding by island or region.

[–, no value determined]

Location Sublocation Number of 

people

Buildings 

(2010 U.S. dollars)

Economic activity 

(2010 U.S. dollars)

American Samoa Tutuila 570 25,019,327 7,074,370

American Samoa Ofu and Olosega 3 77,852 41,228

American Samoa Taʻū 8 753,845 148,637

Northern Mariana Islands Saipan 396 5,003,426 8,047,866

Northern Mariana Islands Tinian 7 672,257 145,767

Guam Guam 107 6,839,500 10,155,754

Florida Peninsula 4,947 323,835,761 276,082,074

Florida Florida Keys 716 32,125,237 42,970,125

Hawaiʻi Island of Hawaiʻi 336 23,997,824 26,686,848

Hawaiʻi Maui 3,381 112,716,317 264,474,795

Hawaiʻi Lānaʻi 0 53,732 1,359

Hawaiʻi Molokaʻi 1 42,071 73,122

Hawaiʻi Kahoʻolawe – – –

Hawaiʻi Oʻahu 3,040 200,942,259 194,404,235

Hawaiʻi Kauaʻi 107 5,854,742 6,466,170

Hawaiʻi Niʻihau 0 0 1,066

Puerto Rico Isla de Puerto Rico 4,210 65,880,224 117,301,923

Puerto Rico Isla de Culebra 11 148,502 286,275

Puerto Rico Isla de Vieques 0 94,075 9,710

Virgin Islands Saint Croix 278 18,021,883 21,325,668

Virgin Islands Saint John 3 527,814 323,358

Virgin Islands Saint Thomas 59 3,319,769 3,565,110
Results 19

Table 10. Total number of essential facilities protected by coral reefs from flooding for different return-interval storms by region.

Infrastructure type Location Storm return interval

10-year 50-year 100-year 500-year

Hospitals American Samoa 0 0 0 0

Northern Mariana Islands 0 0 0 0

Guam 0 0 0 0

Florida 0 0 0 0

Hawaiʻi 1 2 2 0

Puerto Rico 0 1 1 4

Virgin Islands 0 0 0 0

Police stations American Samoa 0 0 0 1

Northern Mariana Islands 0 0 0 0

Guam 0 0 0 0

Florida 1 0 2 3

Hawaiʻi 0 0 0 0

Puerto Rico 3 5 6 7

Virgin Islands 1 0 0 0

Fire stations American Samoa 0 0 0 0

Northern Mariana Islands 0 0 0 0

Guam 0 0 0 0

Florida 1 2 3 6

Hawaiʻi 2 3 2 0

Puerto Rico 0 0 0 1

Virgin Islands 0 0 2 1

Schools American Samoa 1 0 0 0

Northern Mariana Islands 0 1 1 0

Guam 0 0 0 0

Florida 2 1 2 1

Hawaiʻi 2 2 6 1

Puerto Rico 4 5 6 18

Virgin Islands 0 0 0 0

Emergency operation centers American Samoa 0 0 0 0

Northern Mariana Islands 0 0 0 0

Guam 0 0 0 0

Florida 0 0 0 1

Hawaiʻi 0 0 0 0

Puerto Rico 0 0 0 1

Virgin Islands 0 0 0 0
20 Rigorously Valuing Coral Reef Coastal Protection

Table 11. Total number of lifeline utility systems protected by coral reefs from flooding for different return-interval storms by region.

Infrastructure type Location Storm return interval

10-year 50-year 100-year 500-year

Water American Samoa 0 0 0 0

Northern Mariana Islands 0 0 0 0

Guam 0 0 0 0

Florida 0 0 0 2

Hawaiʻi 0 0 0 0

Puerto Rico 0 0 0 1

Virgin Islands 0 0 0 0

Wastewater American Samoa 0 0 0 0

Northern Mariana Islands 0 0 0 0

Guam 0 0 0 0

Florida 0 0 0 0

Hawaiʻi 2 2 1 0

Puerto Rico 0 1 1 2

Virgin Islands 0 0 0 0

Electrical American Samoa 0 0 0 0

Northern Mariana Islands 0 0 0 0

Guam 0 0 0 0

Florida 1 0 0 0

Hawaiʻi 2 2 1 0

Puerto Rico 0 0 0 0

Virgin Islands 0 0 0 0

Oil and gas American Samoa 0 0 0 0

Northern Mariana Islands 0 0 0 0

Guam 0 0 0 0

Florida 0 0 0 0

Hawaiʻi 1 1 1 0

Puerto Rico 0 0 0 0

Virgin Islands 0 0 0 0

Communications American Samoa 0 0 0 0

Northern Mariana Islands 0 0 0 0

Guam 0 0 0 0

Florida 0 0 0 0

Hawaiʻi 3 3 0 0

Puerto Rico 0 0 1 1

Virgin Islands 0 0 0 0
Results 21

Table 12. Total transportation systems protected by coral reefs from flooding for different return-interval storms by region.

[Values for highways in kilometers; port and airport values are number of facilities]

Infrastructure type Location Storm return interval

10-year 50-year 100-year 500-year

Highways American Samoa 0 0 0 0

Northern Mariana Islands 0 0 0 0

Guam 0 0 0 0

Florida 2.513 6.049 9.490 22.175

Hawaiʻi 30.376 31.943 31.175 28.179

Puerto Rico 4.498 7.302 9.710 15.566

Virgin Islands 0 0 0 0

Ports American Samoa 0 0 0 0

Northern Mariana Islands 0 0 0 0

Guam 0 0 0 0

Florida 0 1 4 1

Hawaiʻi 3 5 0 4

Puerto Rico 0 0 0 0

Virgin Islands 0 0 0 0

Airports American Samoa 0 0 0 0

Northern Mariana Islands 0 0 0 0

Guam 0 0 0 0

Florida 0 1 1 0

Hawaiʻi 0 0 0 0

Puerto Rico 0 0 0 1

Virgin Islands 0 0 0 0

Table 13. Critical infrastructure protected by coral reefs from flooding annually by region.

[km, kilometers]

Location Number of 

essential facilities

Number of 

lifeline utilities

Number of 

transportation systems

American Samoa 0.95 0 0

Northern Mariana Islands 0.07 0 0

Guam 0 0 0

Florida 4.12 0.96 0.28

Hawaiʻi 5.24 7.97 3.42

Puerto Rico 7.61 0.12 0.01

Virgin Islands 0.98 0 0
22 Rigorously Valuing Coral Reef Coastal Protection

Evaluating Additional Potential 

Scenarios

The entire flood and impact model structure can also 

be implemented for different potential scenarios to evaluate 

climate, social, and economic changes. These scenarios can 

include: (a) various elevations of sea-level rise; (b) population 

and economic growth; and (c) a change in reef health that 

causes a change in coral cover and thus frictional effects. 

Scenario (a) could be used to determine how projected 

21st-century sea-level rise (Vermeer and Rahmstorf, 2009; 

Grinsted and others, 2010; Kopp and others, 2014) may 

reduce the effectiveness of corals reefs in coastal hazard risk 

reduction, whereas scenario (b) can demonstrate how the 

importance of coral reefs in coastal hazard risk reduction will 

change with projected population growth in coastal areas 

based on datasets such as those provided by Neumann and 

others (2015), the United Nation’s (2016) world population 

prospects, and the International Institute for Applied Systems 

Analysis’ shared socioeconomic pathways database (Riahi 

and others, 2017). Lastly, scenario (c) can provide guidance 

as to where coral reef restoration (Fox and others, 2005; 

Haisfield and others, 2010; Rinkevich, 2015; Montoya-May 

and others, 2016) would be most effective in terms of coastal 

hazard risk reduction, as quantified by people, assets, and 

infrastructure protected or the potential impact of coral reef 

degradation on coastal hazards.

Conclusions

Here, we present a new methodology to combine 

engineering, ecologic, geospatial, social, and economic 

tools to provide a rigorous social and economic valuation 

of the coastal protection benefits of coral reefs off the U.S. 

States of Hawaiʻi and Florida, the U.S. territories of Guam, 

American Samoa, Puerto Rico, and the Virgin Islands, and 

the Commonwealth of the Northern Mariana Islands. The 

resulting data make it possible to identify where, when, 

and how U.S. coral reefs provide the most significant flood 

reduction benefits. The goal is to provide sound, scientific 

guidance for U.S. Federal, State, territorial, and local 

governments’ efforts on coral reef conservation, restoration, 

and management by providing rigorous, spatially explicit, 

high-resolution, social and economic valuations of the people 

and property protected by coral reefs to, ultimately, save 

dollars and protect lives. In addition, the data presented here 

can inform new financing opportunities for reef management. 

Assessing risk reduction benefits in economic terms will 

advance decision making for coral reefs and allow new 

investments in reef conservation and management from 

new funding sources, such as defense, transportation, and 

emergency management agencies.

Acknowledgments

This work was carried out as part of the U.S. Geological 

Survey’s (USGS) Coral Reef Project, with principle funding 

from the Coastal and Marine Geology Program as part 

of an effort in the United States and its trust territories to 

better understand the effect of geologic and oceanographic 

processes on coral reef systems. This work was also 

supported by a grant from the U.S. Department of Interior 

Office of Insular Affairs (OIA) to The Nature Conservancy 

and the University of California at Santa Cruz. This work 

was inspired by a conversation with Bill Werkheiser (USGS) 

and got off the ground and running by Karen Koltes (OIA). 

Amy Foxgrover (USGS) and Kurt Rosenberger (USGS) 

contributed numerous excellent suggestions and a timely 

review of our work. 

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Additional Digital Information

The digital data used to produce this report can be found in:

Gibbs, A.E., Cole, A.D., Lowe, E., Reguero, B.G., and Storlazzi, C.D., 2019, 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 Hawaiʻi and 

Florida, the territories of Guam, American Samoa, Puerto 

Rico, and the U.S. Virgin Islands, and the Commonwealth 

of the Northern Mariana Islands: U.S. Geological Survey 

data release, https://doi.org/10.5066/P9KMH2VX. 

For more information on the U.S. Geological Survey’s Coral Reef 

Project, visit https://coralreefs.wr.usgs.gov.

For more information on the U.S. Geological Survey Coastal and 

Marine Program’s Coastal Change Hazards portal, visit https://

marine.usgs.gov/coastalchangehazardsportal.

For more information on The Nature Conservancy’s 

Global Oceans Program, visit https://global.nature.org/

our-global-solutions/oceans.

For more information on The Nature Conservancy’s Coastal 

Resilience platform, visit https://coastalresilience.org.

For more information on the University of California at Santa 

Cruz’s Center for Integrated Spatial Research, visit http://spatial.

cisr.ucsc.edu.

For more information on Deltares’ Hydro- and Morphodynamics 

During Extreme Events group, visit https://www.deltares.nl/en/

issues/event-driven-hydro-morphodynamics.

Contact Information

Regarding this report, contact Curt D. Storlazzi (USGS Coral 

Reef Project Chief) at cstorlazzi@usgs.gov.
Appendixes
30 Rigorously Valuing Coral Reef Coastal Protection

Appendix 1. SWAN Model Settings

Parameter Value

General

OnlyInputVerify false

SimMode stationary

DirConvention nautical

WindSpeed 0.0000000e+000

WindDir 0.0000000e+000

Processes

GenModePhys 3

Breaking true

BreakAlpha 1.0000000e+000

BreakGamma 7.3000002e−001

Triads false

TriadsAlpha 1.0000000e−001

TriadsBeta 2.2000000e+000

WaveSetup false

BedFriction jonswap

BedFricCoef 6.7000002e−002

Diffraction true

DiffracCoef 2.0000000e−001

DiffracSteps 5

DiffracProp true

WindGrowth false

WhiteCapping Komen

Quadruplets false

Refraction true

FreqShift true

WaveForces dissipation 3d

Numerics

DirSpaceCDD 5.0000000e−001

FreqSpaceCSS 5.0000000e−001

RChHsTm01 2.0000000e−002

RChMeanHs 2.0000000e−002

RChMeanTm01 2.0000000e−002

PercWet 9.8000000e+001

MaxIter 100

Output

TestOutputLevel 0

TraceCalls false

UseHotFile false

WriteCOM false

Domain

DirSpace circle

NDir 72

StartDir 0.0000000e+000

EndDir 0.0000000e+000

FreqMin 5.0000001e−002

FreqMax 1.0000000e+000

NFreq 24

Output true

Parameter Value

Boundary

Definition orientation

SpectrumSpec parametric

SpShapeType jonswap

PeriodType peak

DirSpreadType power

PeakEnhanceFac 3.3000000e+000

GaussSpread 9.9999998e−003
Appendix 2. SWAN Model Grid Information

[km, kilometer; m, meter; NGDC, National Geophysical Data Center; PacIOOS, Pacific Islands Ocean Observing System]

Location 5-km 

grid cells

1-km 

grid cells

200-m 

grid cells

Grid dimensions 

(E-W × N-S) Data source

American Samoa AmSam 164 × 28 Lim and others, 2010

American Samoa Tutuila 235 × 100 Carignan and others, 2013

American Samoa Ofu-Olosega & Tau 155 × 79 Lim and others, 2010

Northern Mariana Islands Saipan 151 × 136 PacIOOS, 2016a

Northern Mariana Islands Tinian 127 × 155 PacIOOS, 2016b

Guam Guam 221 × 285 Chamberlin, 2008

Florida Dry Tortugas 295 × 190 NGDC, 2001

Florida Key West 505 × 255 NGDC, 2001

Florida Marathon 505 × 337 NGDC, 2001

Florida Islamorada 383 × 334 NGDC, 2001

Florida Miami 291 × 502 NGDC, 2001

Hawaiʻi HiChain 295 × 192 NGDC, 2005

Hawaiʻi Hawaii 142 × 159 NGDC, 2005

Hawaiʻi Hawaii_North 400 × 190 NGDC, 2005

Hawaiʻi Hawaii_East 235 × 300 NGDC, 2005

Hawaiʻi Hawaii_Southeast 310 × 160 NGDC, 2005

Hawaiʻi Hawaii_South 350 × 205 NGDC, 2005

Hawaiʻi Hawaii_West 185 × 400 NGDC, 2005

Hawaiʻi MauiNui 146 × 86 NGDC, 2005

Hawaiʻi Lanai 145 × 120 NGDC, 2005

Hawaiʻi Kahoolawe 115 × 170 NGDC, 2005

Hawaiʻi Molokai 146 × 86 NGDC, 2005

Hawaiʻi Maui_East 265 × 220 NGDC, 2005

Hawaiʻi Maui_West 195 × 230 NGDC, 2005

Hawaiʻi Oahu 420 × 290 NGDC, 2005

Hawaiʻi Kauai 293 × 242 NGDC, 2005

Hawaiʻi Niihau 128 × 178 NGDC, 2005

Puerto Rico PR_all 245 × 94 Taylor and others, 2008b

Puerto Rico PR_North-Central 330 × 155 Taylor and others, 2008b

Puerto Rico PR_Northeast 330 × 155 Taylor and others, 2008b

Puerto Rico PR_Northwest 315 × 155 Taylor and others, 2008b

Puerto Rico PR_South-Central 320 × 160 Taylor and others, 2008b

Puerto Rico PR_Southeast 320 × 165 Taylor and others, 2008b

Puerto Rico PR_Southwest 230 × 160 Taylor and others, 2008b

Virgin Islands USVI 74 × 108 Love and others, 2014a, b

Virgin Islands StCroix 260 × 115 Love and others, 2014a, b

Virgin Islands StJohnStThomas 270 × 206 Love and others, 2014a, b

Appendix 2 31
32 Rigorously Valuing Coral Reef Coastal Protection

Appendix 3. Benthic Habitat and Shoreline Datasets 

[FFWCC, Florida Fish and Wildlife Conservation Commission; FWRI, Fish and Wildlife Research Institute; NOAA, National Oceanic and Atmospheric 

Administration; m2, square meters]

Location Sublocation

Benthic habitat data

Shoreline data source

Minimum mapping unit Data source

American Samoa Tutuila 1 acre Anderson, 2004a NOAA, 2002d

American Samoa Ofu and Olosega 1 acre Anderson, 2004a NOAA, 2002a

American Samoa Taʻū 1 acre Anderson, 2004a NOAA, 2002a

Northern Mariana Islands Saipan 1 acre Anderson, 2004c NOAA, 2002b

Northern Mariana Islands Tinian 1 acre Anderson, 2004c NOAA, 2002c

Guam Guam 1 acre Anderson, 2004b NOAA, 2003

Florida Dry Tortugas <1 acre FFWCC-FWRI, 2016 NOAA, 2015

Florida Key West <1 acre FFWCC-FWRI, 2016 NOAA, 2015

Florida Florida Keys <1 acre FFWCC-FWRI, 2016 NOAA, 2015

Florida Miami <1 acre FFWCC-FWRI, 2016 NOAA, 2015

Florida Palm Beach <1 acre FFWCC-FWRI, 2016 NOAA, 2015

Hawaiʻi Island of Hawaiʻi 1 acre Anderson, 2007 State of Hawaii, 1997

Hawaiʻi Maui 1 acre Anderson, 2007 State of Hawaii, 1997

Hawaiʻi Lānaʻi 1 acre Anderson, 2007 State of Hawaii, 1997

Hawaiʻi Molokaʻi 1 acre Anderson, 2007 State of Hawaii, 1997

Hawaiʻi Kahoʻolawe 1 acre Anderson, 2007 State of Hawaii, 1997

Hawaiʻi Kauaʻi 1 acre Anderson, 2007 State of Hawaii, 1997

Hawaiʻi Niʻihau 1 acre Anderson, 2007 State of Hawaii, 1997

Hawaiʻi Oʻahu 1 acre Anderson, 2007 State of Hawaii, 1997

Puerto Rico Isla de Puerto Rico 1 acre NOAA, 2001a NOAA, 2015

Puerto Rico Isla de Culebra 1 acre NOAA, 2001a NOAA, 2015

Puerto Rico Isla de Vieques 1 acre NOAA, 2001a NOAA, 2015

Virgin Islands Saint Croix 1 acre NOAA, 2001b NOAA, 2015

Virgin Islands Saint John 1,000 m2 Zitello and others, 2009 NOAA, 2015

Virgin Islands Saint Thomas 1 acre NOAA, 2001c NOAA, 2015
Appendix 4. Cross-shore XBeach Transects 

Location Sublocation Number of cross-shore transects

American Samoa Tutuila 1,004

American Samoa Ofu and Olosega 196

American Samoa Taʻū 275

Northern Mariana Islands Saipan 585

Northern Mariana Islands Tinian 450

Guam Guam 1,295

Florida Dry Tortugas 300

Florida Key West 545

Florida Florida Keys 1,127

Florida Miami 1,139

Florida Palm Beach 1,168

Hawaiʻi Island of Hawaiʻi 4,582

Hawaiʻi Maui 2,087

Hawaiʻi Lānaʻi 759

Hawaiʻi Molokaʻi 2,886

Hawaiʻi Kahoʻolawe 456

Hawaiʻi Kauaʻi 1,455

Hawaiʻi Niʻihau 677

Hawaiʻi Oʻahu 1,997

Puerto Rico Isla de Puerto Rico 4,588

Puerto Rico Isla de Culebra 244

Puerto Rico Isla de Vieques 687

Virgin Islands Saint Croix 803

Virgin Islands Saint John 396

Virgin Islands Saint Thomas 466

Appendix 4 33
34 Rigorously Valuing Coral Reef Coastal Protection

Appendix 5. Bathymetric and Topographic Datasets 

[NGDC, National Geophysical Data Center; NOAA, National Oceanic and Atmospheric Administration; PacIOOS, Pacific Islands Ocean Observing System; 

PIBHMC, Pacific Islands Benthic Habitat Mapping Center]

Location Sublocation Data source

American Samoa Tutuila Carignan and others, 2013

American Samoa Ofu, Olosega, and Taʻū Lim and others, 2010

Northern Mariana Islands Saipan PIBHMC, 2007a

Amante and Eakins, 2009

PacIOOS, 2016a

Northern Mariana Islands Tinian PIBHMC, 2007b

Amante and Eakins, 2009

PacIOOS, 2016b

Guam Guam Chamberlin, 2008

Florida Dry Tortugas NGDC, 2001

Florida Key West Grothe and others, 2011

Florida Florida Keys NGDC, 2001

Florida Miami Carignan and others, 2015

Florida Palm Beach NGDC, 2001

Hawaiʻi Island of Hawaiʻi NGDC, 2005

Hawaiʻi Hilo Love and others, 2011a

Hawaiʻi Kawaihae Carignan and others, 2011a

Hawaiʻi Keauhou Carignan and others, 2011b

Hawaiʻi Maui Nui NGDC, 2005

Hawaiʻi Maui NOAA, 2016

Taylor and others, 2008a

Hawaiʻi Lānaʻi NGDC, 2005

Hawaiʻi Molokaʻi NGDC, 2005

Hawaiʻi Kahoʻolawe NGDC, 2005

Hawaiʻi Kauaʻi Friday and others, 2012

Hawaiʻi Niʻihau Friday and others, 2012

Hawaiʻi Oʻahu Love and others, 2011b

Puerto Rico Arecibo Taylor and others, 2008c

Puerto Rico Isla de Culebra Taylor and others, 2008b

Puerto Rico Fajardo Taylor and others, 2008d

Puerto Rico Guayama Taylor and others, 2008e

Puerto Rico Mayagüez Taylor and others, 2008f

Puerto Rico Ponce Taylor and others, 2008g

Puerto Rico San Juan Taylor and others, 2008h

Puerto Rico Isla de Vieques Taylor and others, 2008b

Virgin Islands Saint Croix Love and others, 2014a

Virgin Islands Saint Thomas Love and others, 2014b

Virgin Islands Saint John Love and others, 2014b
Appendix 6. XBeach Model Settings

Category Parameter Value

Flow boundary condition parameters front abs_1d

left wall

right wall

back wall

Flow bedfriction chezy

bedfricfile fric.txt

Grid parameters thetamin -60

thetamax 60

dtheta 10

Model time tstop 3600

Tide boundary conditions tideloc 1

Wave boundary condition parameters instat jons

dir0 270

Output variables outputformat netcdf

rugdepth 0.020000

tintm 3500

tintp 10

tintg 3100

tstart 100

Output options nglobalvar 4

H

zs

zb

E

nmeanvar 3

H

zs

zb

npoints 1

nrugauge 1

Appendix 6 35
36 Rigorously Valuing Coral Reef Coastal Protection

Appendix 7. Societal Impacts by Demographics

Table 7.1. Number of children protected by coral reefs from flooding for different return-interval storms by island or region.

[–, no value determined]

Location Sublocation Storm return interval

10-year 50-year 100-year 500-year

American Samoa Tutuila 383 370 364 236

American Samoa Ofu and Olosega 2 3 3 5

American Samoa Taʻū 6 7 7 10

Northern Mariana Islands Saipan 195 240 154 435

Northern Mariana Islands Tinian 2 13 15 6

Guam Guam 56 45 57 90

Florida Peninsula 646 1,515 2,103 6,726

Florida Florida Keys 173 582 610 257

Hawaiʻi Island of Hawaiʻi 99 124 129 141

Hawaiʻi Maui 1,241 1,220 872 558

Hawaiʻi Lānaʻi 0 0 0 0

Hawaiʻi Molokaʻi 1 1 1 2

Hawaiʻi Kahoʻolawe – – – –

Hawaiʻi Oʻahu 1,227 1,339 900 757

Hawaiʻi Kauaʻi 35 33 64 77

Hawaiʻi Niʻihau 0 0 0 0

Puerto Rico Isla de Puerto Rico 1,354 2,477 3,483 8,540

Puerto Rico Isla de Culebra 2 4 5 13

Puerto Rico Isla de Vieques 0 0 0 0

Virgin Islands Saint Croix 122 176 235 106

Virgin Islands Saint John 1 1 4 1

Virgin Islands Saint Thomas 22 23 19 15

Table 7.2. Number of senior citizens protected by coral reefs from flooding for different return-interval storms by island or region.

[–, no value determined]

Location Sublocation

Storm return interval

10-year 50-year 100-year 500-year

American Samoa Tutuila 47 44 42 27

American Samoa Ofu and Olosega 0 1 1 1

American Samoa Taʻū 1 1 1 2

Northern Mariana Islands Saipan 20 26 16 45

Northern Mariana Islands Tinian 0 1 1 0

Guam Guam 15 11 14 24

Florida Peninsula 2,836 5,728 6,584 14,742

Florida Florida Keys 156 525 581 339

Hawaiʻi Island of Hawaiʻi 105 122 124 132

Hawaiʻi Maui 748 684 489 277

Hawaiʻi Lānaʻi 0 0 0 0

Hawaiʻi Molokaʻi 0 0 0 2

Hawaiʻi Kahoʻolawe – – – –

Hawaiʻi Oʻahu 689 636 508 458

Hawaiʻi Kauaʻi 25 28 37 33

Hawaiʻi Niʻihau 0 0 0 0

Puerto Rico Isla de Puerto Rico 1,299 2,465 3,407 5,595

Puerto Rico Isla de Culebra 6 10 11 18

Puerto Rico Isla de Vieques 0 1 1 1

Virgin Islands Saint Croix 63 91 114 58

Virgin Islands Saint John 1 1 3 1

Virgin Islands Saint Thomas 14 14 12 9
Table 7.3. Number of low-income (<$20,000 per year) individuals protected by coral reefs from flooding for different return-interval 

storms by island or region.

[–, no value determined]

Location Sublocation Storm return interval

10-year 50-year 100-year 500-year

American Samoa Tutuila 55 53 52 34

American Samoa Ofu and Olosega 1 1 1 2

American Samoa Taʻū 1 2 2 2

Northern Mariana Islands Saipan 92 113 72 210

Northern Mariana Islands Tinian 1 4 5 2

Guam Guam 10 8 10 15

Florida Peninsula 862 1,896 2,203 5,753

Florida Florida Keys 68 205 236 157

Hawaiʻi Island of Hawaiʻi 45 52 52 49

Hawaiʻi Maui 346 354 272 158

Hawaiʻi Lānaʻi 0 0 0 0

Hawaiʻi Molokaʻi 0 0 0 1

Hawaiʻi Kahoʻolawe – – – –

Hawaiʻi Oʻahu 158 145 81 73

Hawaiʻi Kauaʻi 19 21 38 50

Hawaiʻi Niʻihau – – – –

Puerto Rico Isla de Puerto Rico 1,461 2,681 3,647 8,320

Puerto Rico Isla de Culebra 5 9 11 23

Puerto Rico Isla de Vieques 0 0 1 1

Virgin Islands Saint Croix 55 82 108 46

Virgin Islands Saint John 0 1 2 1

Virgin Islands Saint Thomas 8 7 6 5

Table 7.4. Number of racial or ethnical minority individuals protected by coral reefs from flooding for different return-interval storms by 

island or region.

[–, no value determined]

Location Sublocation Storm return interval

10-year 50-year 100-year 500-year

American Samoa Tutuila 32 35 35 28

American Samoa Ofu and Olosega – – – –

American Samoa Taʻū 0 0 0 0

Northern Mariana Islands Saipan 403 509 321 914

Northern Mariana Islands Tinian 4 24 27 10

Guam Guam 44 35 44 70

Florida Peninsula 2,166 4,675 6,879 21,530

Florida Florida Keys 380 1,348 1,246 597

Hawaiʻi Island of Hawaiʻi 112 133 135 140

Hawaiʻi Maui 1,860 1,807 1,269 837

Hawaiʻi Lānaʻi 0 0 0 0

Hawaiʻi Molokaʻi 0 0 0 1

Hawaiʻi Kahoʻolawe – – – –

Hawaiʻi Oʻahu 1,377 1,499 1,000 1,002

Hawaiʻi Kauaʻi 43 26 37 34

Hawaiʻi Niʻihau 0 0 0 0

Puerto Rico Isla de Puerto Rico 6,638 12,038 17,003 34,333

Puerto Rico Isla de Culebra 15 28 34 78

Puerto Rico Isla de Vieques 0 0 0 1

Virgin Islands Saint Croix 489 702 920 415

Virgin Islands Saint John 3 5 17 4

Virgin Islands Saint Thomas 98 98 81 66

Appendix 7 37
38 Rigorously Valuing Coral Reef Coastal Protection

Appendix 8. Economic Impacts by Building Structure Type

Table 8.1. Value of residential infrastructure protected by coral reefs from flooding for different return-interval storms by island or region.

[Values in 2010 U.S. dollars. –, no value determined]

Location Sublocation Storm return interval

10-year 50-year 100-year 500-year

American Samoa Tutuila 33,831,291 35,131,604 38,529,048 32,590,895

American Samoa Ofu and Olosega 67,572 99,621 138,684 195,713

American Samoa Taʻū 979,633 1,253,973 1,405,927 1,367,881

Northern Mariana Islands Saipan 3,649,547 5,934,616 6,190,926 15,359,567

Northern Mariana Islands Tinian 891,117 1,466,437 1,641,087 2,499,046

Guam Guam 6,614,534 6,486,163 8,223,696 12,904,144

Florida Peninsula 393,787,800 870,988,321 1,114,074,635 3,640,927,246

Florida Florida Keys 35,096,182 92,403,630 121,715,476 87,232,583

Hawaiʻi Island of Hawaiʻi 31,979,469 38,307,443 39,460,911 44,747,586

Hawaiʻi Maui 136,066,606 153,366,244 147,298,242 135,261,344

Hawaiʻi Lānaʻi 97,224 104,730 105,981 106,313

Hawaiʻi Molokaʻi 72,094 85,088 103,682 269,043

Hawaiʻi Kahoʻolawe – – – –

Hawaiʻi Oʻahu 250,403,517 245,814,252 244,366,409 245,122,832

Hawaiʻi Kauaʻi 9,617,881 13,906,300 18,061,072 22,350,362

Hawaiʻi Niʻihau 0 0 0 0

Puerto Rico Isla de Puerto Rico 106,402,960 192,671,038 272,776,125 503,020,038

Puerto Rico Isla de Culebra 232,754 498,925 693,718 1,439,367

Puerto Rico Isla de Vieques 175,922 126,877 148,189 207,562

Virgin Islands Saint Croix 22,687,346 34,500,315 41,869,134 43,546,376

Virgin Islands Saint John 677,743 1,182,595 2,813,744 1,542,423

Virgin Islands Saint Thomas 4,808,621 6,432,601 6,506,281 7,263,312

Table 8.2. Value of commercial infrastructure protected by coral reefs from flooding for different return-interval storms by island or region.

[Values in 2010 U.S. dollars. –, no value determined]

Location Sublocation Storm return interval

10-year 50-year 100-year 500-year

American Samoa Tutuila 2,497,856 2,891,048 3,320,393 2,998,042

American Samoa Ofu and Olosega 8,878 16,023 25,543 32,671

American Samoa Taʻū 151,389 231,368 260,800 189,936

Northern Mariana Islands Saipan 3,328,281 5,567,321 5,684,539 13,104,137

Northern Mariana Islands Tinian 110,229 178,011 186,918 212,014

Guam Guam 4,707,465 3,276,176 4,476,962 6,618,367

Florida Peninsula 70,779,270 158,484,599 211,204,322 749,154,281

Florida Florida Keys 13,202,009 17,932,476 24,900,544 21,980,419

Hawaiʻi Island of Hawaiʻi 9,468,004 10,641,551 11,058,822 11,935,230

Hawaiʻi Maui 56,580,494 68,875,325 67,116,489 51,672,735

Hawaiʻi Lānaʻi 0 0 0 0

Hawaiʻi Molokaʻi 0 0 0 10,369

Hawaiʻi Kahoʻolawe – – – –

Hawaiʻi Oʻahu 104,592,002 94,887,537 84,407,560 60,415,336

Hawaiʻi Kauaʻi 331,970 473,012 486,311 793,352

Hawaiʻi Niʻihau 0 0 0 0

Puerto Rico Isla de Puerto Rico 431,821 1,450,881 2,473,692 6,519,534

Puerto Rico Isla de Culebra 0 0 0 0

Puerto Rico Isla de Vieques 0 0 0 0

Virgin Islands Saint Croix 5,696,426 11,794,367 15,815,058 9,408,406

Virgin Islands Saint John 134,250 212,102 839,084 238,247

Virgin Islands Saint Thomas 848,282 568,758 422,055 653,870
Table 8.3. Value of industrial infrastructure protected by coral reefs from flooding for different return-interval storms by island or region.

[Values in 2010 U.S. dollars. –, no value determined]

Location Sublocation Storm return interval

10-year 50-year 100-year 500-year

American Samoa Tutuila 378,431 826,556 791,552 503,983

American Samoa Ofu and Olosega 0 0 0 0

American Samoa Taʻū 6,318 9,057 11,360 5,068

Northern Mariana Islands Saipan 247,614 478,146 538,392 1,188,725

Northern Mariana Islands Tinian 21,629 47,556 48,974 57,381

Guam Guam 410,850 450,668 714,616 712,647

Florida Peninsula 4,150,879 9,290,653 11,861,582 36,941,212

Florida Florida Keys 640,065 1,286,780 1,881,503 2,009,020

Hawaiʻi Island of Hawaiʻi 284,080 342,846 397,397 410,465

Hawaiʻi Maui 1,852,122 2,251,687 2,276,914 2,029,730

Hawaiʻi Lānaʻi 0 0 0 0

Hawaiʻi Molokaʻi 0 895 3,175 10,027

Hawaiʻi Kahoʻolawe – – – –

Hawaiʻi Oʻahu 2,828,217 2,801,232 2,781,920 2,985,659

Hawaiʻi Kauaʻi 100,424 105,925 83,095 96,546

Hawaiʻi Niʻihau 0 0 0 0

Puerto Rico Isla de Puerto Rico 106,108 231,371 676,516 1,194,123

Puerto Rico Isla de Culebra 0 0 0 0

Puerto Rico Isla de Vieques 0 0 0 0

Virgin Islands Saint Croix 191,666 384,167 506,723 600,170

Virgin Islands Saint John 3,741 6,211 13,156 18,906

Virgin Islands Saint Thomas 52,075 58,144 57,608 94,079

Table 8.4. Value of government infrastructure protected by coral reefs from flooding for different return-interval storms by island or region.

[Values in 2010 U.S. dollars. –, no value determined]

Location Sublocation Storm return interval

10-year 50-year 100-year 500-year

American Samoa Tutuila 2,051,849 4,282,505 4,544,835 3,720,292

American Samoa Ofu and Olosega 0 0 0 0

American Samoa Taʻū 30,489 24,397 34,071 67,256

Northern Mariana Islands Saipan 179,859 197,541 277,848 670,420

Northern Mariana Islands Tinian 41 300 295 172

Guam Guam 187,436 111,554 174,973 227,319

Florida Peninsula 650,807 1,224,301 1,119,474 8,298,899

Florida Florida Keys 396,259 523,228 540,639 649,911

Hawaiʻi Island of Hawaiʻi 258,004 316,281 329,951 435,692

Hawaiʻi Maui 950,263 1,075,179 1,064,243 445,783

Hawaiʻi Lānaʻi 0 0 0 0

Hawaiʻi Molokaʻi 0 0 0 292

Hawaiʻi Kahoʻolawe – – – –

Hawaiʻi Oʻahu 532,180 426,681 299,716 127,649

Hawaiʻi Kauaʻi 1,902 2,441 2,262 2,402

Hawaiʻi Niʻihau 0 0 0 0

Puerto Rico Isla de Puerto Rico 13 102 142 489,508

Puerto Rico Isla de Culebra 0 0 0 0

Puerto Rico Isla de Vieques 0 0 0 0

Virgin Islands Saint Croix 585,965 952,243 1,359,997 743,617

Virgin Islands Saint John 10,224 24,655 95,277 29,854

Virgin Islands Saint Thomas 33,406 27,517 29,988 29,167

Appendix 8 39
40 Rigorously Valuing Coral Reef Coastal Protection

Table 8.5. Value of educational infrastructure protected by coral reefs from flooding for different return-interval storms by island or region.

[Values in 2010 U.S. dollars. –, no value determined]

Location Sublocation Storm return interval

10-year 50-year 100-year 500-year

American Samoa Tutuila 2,822,995 3,255,719 3,157,165 2,324,187

American Samoa Ofu and Olosega 41,462 47,143 49,964 69,307

American Samoa Taʻū 85,818 150,048 157,648 51,374

Northern Mariana Islands Saipan 801,881 1,014,898 1,050,111 2,273,112

Northern Mariana Islands Tinian 96,753 180,063 187,141 89,008

Guam Guam 173,162 122,408 181,847 283,441

Florida Peninsula 2,097,751 2,232,487 1,727,128 23,268,631

Florida Florida Keys 296,794 415,675 854,154 838,980

Hawaiʻi Island of Hawaiʻi 94,516 147,366 155,592 657,161

Hawaiʻi Maui 1,537,322 1,729,615 1,436,934 1,040,080

Hawaiʻi Lānaʻi 0 0 0 0

Hawaiʻi Molokaʻi 0 6,643 21,661 63,768

Hawaiʻi Kahoʻolawe – – – –

Hawaiʻi Oʻahu 5,213,860 4,746,944 4,346,526 3,852,285

Hawaiʻi Kauaʻi 1,989 5,865 9,344 13,139

Hawaiʻi Niʻihau 0 0 0 0

Puerto Rico Isla de Puerto Rico 162,645 287,589 481,602 1,254,260

Puerto Rico Isla de Culebra 0 0 0 0

Puerto Rico Isla de Vieques 0 0 0 0

Virgin Islands Saint Croix 529,700 1,069,980 1,354,682 877,402

Virgin Islands Saint John 11,407 21,442 97,059 11,299

Virgin Islands Saint Thomas 79,195 66,600 57,996 105,354

Table 8.6. Value of agricultural infrastructure protected by coral reefs from flooding for different return-interval storms by island or region.

[Values in 2010 U.S. dollars. –, no value determined]

Location Sublocation Storm return interval

10-year 50-year 100-year 500-year

American Samoa Tutuila 5,841 4,669 4,789 6,009

American Samoa Ofu and Olosega 0 0 0 0

American Samoa Taʻū 0 0 0 0

Northern Mariana Islands Saipan 4,471 6,039 6,258 7,234

Northern Mariana Islands Tinian 0 0 0 5

Guam Guam 55,548 94,078 114,015 148,902

Florida Peninsula 578,730 1,442,988 2,253,723 5,602,307

Florida Florida Keys 442,971 388,619 485,908 408,680

Hawaiʻi Island of Hawaiʻi 182,334 210,835 233,915 353,157

Hawaiʻi Maui 172,903 270,735 312,827 358,768

Hawaiʻi Lānaʻi 0 0 0 0

Hawaiʻi Molokaʻi 0 0 0 0

Hawaiʻi Kahoʻolawe – – – –

Hawaiʻi Oʻahu 565,015 560,961 522,264 412,447

Hawaiʻi Kauaʻi 7,353 9,058 8,247 11,153

Hawaiʻi Niʻihau 0 0 0 0

Puerto Rico Isla de Puerto Rico 16,899 225,027 539,543 954,575

Puerto Rico Isla de Culebra 0 0 0 53

Puerto Rico Isla de Vieques 0 0 0 0

Virgin Islands Saint Croix 387,698 727,418 878,073 1,426,022

Virgin Islands Saint John 456 2,002 2,752 4,207

Virgin Islands Saint Thomas 3,143 5,603 2,561 3,972
Table 8.7. Value of religious infrastructure protected by coral reefs from flooding for different return-interval storms by island or region.

[Values in 2010 U.S. dollars. –, no value determined]

Location Sublocation Storm return interval

10-year 50-year 100-year 500-year

American Samoa Tutuila 3,473,932 3,842,989 4,948,566 3,008,020

American Samoa Ofu and Olosega 15,992 27,312 42,427 46,125

American Samoa Taʻū 79,047 36,694 43,423 145,552

Northern Mariana Islands Saipan 229,265 311,942 289,177 663,988

Northern Mariana Islands Tinian 15,598 29,585 30,784 12,877

Guam Guam 374,990 304,800 421,156 584,777

Florida Peninsula 24,762,911 43,853,718 91,580,513 175,083,019

Florida Florida Keys 1,227,758 1,588,517 2,016,796 2,238,330

Hawaiʻi Island of Hawaiʻi 609,353 689,573 687,805 1,027,498

Hawaiʻi Maui 5,642,424 6,535,304 6,124,466 3,671,018

Hawaiʻi Lānaʻi 0 0 0 0

Hawaiʻi Molokaʻi 0 16 16 1,285

Hawaiʻi Kahoʻolawe – – – –

Hawaiʻi Oʻahu 4,707,008 3,878,652 3,282,646 1,956,345

Hawaiʻi Kauaʻi 19,269 27,197 25,035 42,272

Hawaiʻi Niʻihau 0 0 0 0

Puerto Rico Isla de Puerto Rico 116,826 262,042 334,877 981,811

Puerto Rico Isla de Culebra 0 0 0 0

Puerto Rico Isla de Vieques 0 0 0 0

Virgin Islands Saint Croix 442,674 1,009,232 1,251,697 733,994

Virgin Islands Saint John 14,330 40,945 104,528 35,394

Virgin Islands Saint Thomas 86,042 94,533 63,107 55,029

Appendix 8 41
42 Rigorously Valuing Coral Reef Coastal Protection

Appendix 9. Economic Impact Caused by Building Damage

Table 9.1. Value of economic activity protected by coral reefs from flooding of residential buildings for different return-interval storms by island 

or region.

[Values in 2010 U.S. dollars. –, no value determined]

Location Sublocation Storm return interval

10-year 50-year 100-year 500-year

American Samoa Tutuila 10,831,935 10,448,474 10,252,015 6,716,110

American Samoa Ofu and Olosega 59,875 84,713 88,234 122,983

American Samoa Taʻū 156,990 179,056 180,752 262,578

Northern Mariana Islands Saipan 10,338,706 12,896,397 8,221,482 23,202,018

Northern Mariana Islands Tinian 134,499 751,074 854,870 330,680

Guam Guam 7,616,135 6,009,842 7,643,102 12,057,258

Florida Peninsula 301,893,380 616,937,288 777,087,694 2,068,552,737

Florida Florida Keys 41,093,945 129,102,830 152,019,985 81,048,150

Hawaiʻi Island of Hawaiʻi 29,652,176 35,797,322 36,706,314 39,324,880

Hawaiʻi Maui 308,765,608 297,132,577 209,291,736 135,838,459

Hawaiʻi Lānaʻi 2,323 3,379 3,287 5,608

Hawaiʻi Molokaʻi 120,000 138,156 160,102 633,857

Hawaiʻi Kahoʻolawe – – – –

Hawaiʻi Oʻahu 276,027,871 278,569,161 195,540,708 175,566,247

Hawaiʻi Kauaʻi 9,522,069 9,355,969 15,467,233 17,562,350

Hawaiʻi Niʻihau 1,620 4,454 3,914 3,914

Puerto Rico Isla de Puerto Rico 180,828,651 328,437,459 465,515,833 932,628,767

Puerto Rico Isla de Culebra 458,726 842,063 1,043,991 2,373,679

Puerto Rico Isla de Vieques 17,019 19,333 28,346 31,696

Virgin Islands Saint Croix 19,312,834 27,982,476 36,585,033 17,160,895

Virgin Islands Saint John 225,862 338,741 993,239 312,446

Virgin Islands Saint Thomas 4,316,419 4,516,121 3,743,125 3,185,976

Table 9.2. Value of economic activity protected by coral reefs from flooding of commercial and (or) industrial buildings for different 

return-interval storms by island or region.

[Values in 2010 U.S. dollars. –, no value determined]

Location Sublocation Storm return interval

10-year 50-year 100-year 500-year

American Samoa Tutuila 2,006,618 2,288,695 2,437,042 1,418,594

American Samoa Ofu and Olosega 10,845 15,751 19,882 17,042

American Samoa Taʻū 103,025 153,582 142,204 166,368

Northern Mariana Islands Saipan 3,709,412 5,602,356 4,406,782 11,891,051

Northern Mariana Islands Tinian 44,405 174,250 202,026 168,565

Guam Guam 11,220,555 7,132,730 10,087,524 12,343,235

Florida Peninsula 136,062,228 268,419,324 308,684,446 899,154,497

Florida Florida Keys 20,653,909 65,705,675 93,180,870 79,067,592

Hawaiʻi Island of Hawaiʻi 17,666,264 19,197,111 19,863,118 20,182,236

Hawaiʻi Maui 177,101,838 167,510,809 102,446,382 50,210,743

Hawaiʻi Lānaʻi 0 0 0 0

Hawaiʻi Molokaʻi 0 32,111 74,925 249,032

Hawaiʻi Kahoʻolawe – – – –

Hawaiʻi Oʻahu 78,933,923 74,040,006 50,507,922 48,049,127

Hawaiʻi Kauaʻi 2,077,952 1,342,448 1,443,273 2,316,032

Hawaiʻi Niʻihau 0 0 0 0

Puerto Rico Isla de Puerto Rico 5,938,640 13,909,025 22,954,144 44,143,060

Puerto Rico Isla de Culebra 0 0 0 0

Puerto Rico Isla de Vieques 0 0 0 0

Virgin Islands Saint Croix 16,762,707 29,321,522 32,800,249 15,034,613

Virgin Islands Saint John 285,517 462,560 1,750,487 479,596

Virgin Islands Saint Thomas 2,268,680 1,134,587 842,692 1,130,473
Menlo Park Publishing Service Center, California

Manuscript approved for publication March 14, 2019

Edited by Monica Erdman

Design and layout by Cory Hurd
Storlazzi and others—Rigorously Valuing the Role of U.S. Coral Reefs in Coastal Hazard Risk Reduction—Open-File Report 2019–1027

ISSN 2331-1258 (online)

https://doi.org/10.3133/ofr20191027