Quantifying Flood Risk and Reef Risk Reduction Benefits in Florida and Puerto Rico: The Consequences of Hurricane Damage, Long-term Degradation, and Restoration Opportunities

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Coastal flooding and erosion from extreme weather events affect thousands of vulnerable coastal communities; the impacts of coastal flooding are predicted to worsen during this century because of population growth and climate change. Hurricanes Irma and Maria in 2017 were particularly devasting to humans and natural communities. The coral reefs off the State of Florida and the Commonwealth of Puerto Rico have been shown to provide considerable coastal flood reduction benefits; it is highly likely that storm damage to those coral reefs increased future flood risk to people, property, and natural resources. In these studies, we aimed to quantify by just how much and then to determine where coral reef restoration could reduce those risks and protect Florida's and Puerto Rico's coastal communities. The significant flood risk consequences of coral reef damage, degradation, and restoration demonstrate the defense benefits from this natural infrastructure and exemplify why the U.S. Coral Reef Task Force's goals to protect, preserve, and restore U.S. coral reefs also will increase the resiliency of the Nation's coastal communities.

Coastline with data plotted on top to quantify the amount of flood risk with how much could be saved with restoration efforts.

The full height of the bars indicates current expected flood risk in the 100-year floodplain in Miami, Florida. The blue bar tops indicate the risk that could be reduced with reef restoration; their height and color represent the expected benefit from restoration per 100,000 m2 (hexagon max width = 392 m). Residual risk remains even after reef restoration. The orange line offshore indicates the location of potential reef restoration assessed in the models. The blue polygons offshore represent the extent of current reef habitats. Public domain.

The purpose of these reports is to provide information to supplement the USGS Recovery Activities described in USGS Fact Sheet 2018-3063 in response to the 2018 Additional Supplemental Appropriations for Disaster Relief Requirements Act. Hurricanes Irma and Maria in 2017 caused widespread damage to coral reefs and to coastal communities across Florida and Puerto Rico. The aim of this work is to quantify how and where the damage and degradation of reefs could increase flood risk and to identify if and how reef restoration could reduce these risks.

There is growing recognition of the role of nature-based solutions, such as coral reef restoration, to reduce coastal risks. One of 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 the social and economic benefits.   

To address this limitation, the USGS led a collaborative effort with the University of California at Santa Cruz (UCSC) and the National Oceanic and Atmospheric Administration (NOAA) to investigate the role of U.S. coral reefs in coastal hazard risk reduction. The goals were to rigorously and quantitatively assess how:

  1. Storm damage to reefs in 2017 reduced their flood protection benefits in Puerto Rico and Florida;
  2. Ongoing degradation of reefs in Florida is likely to increase future flood risk; and
  3. Flood protection to people and property could be enhanced through reef restoration.

Risk-based valuation approaches were applied to map flood zones at 10 m2 resolution along all 980+ kilometers of Florida’s and Puerto Rico’s reef-lined shorelines for different storm probabilities. The coastal flood risk reduction benefits provided by coral reef damage, potential restoration, or projected degradation were quantified using the information from the U.S. Census Bureau, U.S. Federal Emergency Management Agency, and U.S. Bureau of Economic Analysis.

The protection lost in Florida and Puerto Rico from storm damage to coral reefs during the 2017 Hurricanes Irma and Maria could result in: 

  • Increased flooding affecting >4,300 people annually 
  • Increased direct damages of >$57.2 million to >1,800 buildings annually 
  • Increased indirect damages to >$124.3 million in economic activity due to housing and business damage annually 

The protection lost in Florida due to projected future coral reef degradation could result in: 

  • Increased flooding affecting >7,300 people annually 
  • Increased direct damages of >$385.4 million to >1,400 buildings annually 
  • Increased indirect damages to >$438.1 million in economic activity due to housing and business damage annually 

The protection gained in Florida and Puerto Rico from potential coral reef restoration could result in: 

  • Avoided flooding affecting >3,100 people annually 
  • Avoided direct damages of >$124.2 million to >890 buildings annually 
  • Avoided indirect damages to >$148.7 million in economic activity due to housing and business damage annually 

Federal, State, Commonwealth, and local government agencies can use this information to help prioritize actions and investments by:

  • Flood risk managers aiming to understand and mitigate current and future flood risks;
  • Hazard management agencies, municipalities, and organizations aiming to reduce coastal risks by investing in the restoration of natural infrastructure and natural and nature-based features;
  • Conservation and restoration investments by agencies and NGOs aiming to improve coastal resilience; and
  • Public and private insurers aiming to incentivize and invest in nature-based solutions for adaptation and risk reduction.

 

Report Summary Pamphlets Report Maps
Hurricane damage:

Potential restoration:

Projected degradation:

Hurricane damage:

Potential restoration:

Projected degradation:

 

U.S. Geological Survey Open-File Reports

Storlazzi, C.D., Reguero, B.G., Viehman, T.S., Cumming, K.A., Cole, A.D., Shope, J.A., Groves, S.H., Gaido L., C., Nickel, B.A., and Beck, M.W., 2021, Rigorously valuing the impact of Hurricanes Irma and Maria on coastal hazard risks in Florida and Puerto Rico: U.S. Geological Survey Open-File Report 2021–1056, 29 p., https://doi.org/10.3133/ofr20211056.  

Storlazzi, C.D., Reguero, B.G., Cumming, K.A., Cole, A.D., Shope, J.A., Gaido L., C., Viehman, T.S., Nickel, B.A., and Beck, M.W., 2021, Rigorously valuing the coastal hazard risks reduction provided by potential coral reef restoration in Florida and Puerto Rico: U.S. Geological Survey Open-File Report 2021–1054, 35 p., https://doi.org/10.3133/ofr20211054

Storlazzi, C.D., Reguero, B.G., Yates, K.K., Cumming, K.A., Cole, A.D., Shope, J.A., Gaido L., C., Zawada, D.G., Arsenault, S.R., Fehr, Z.W., Nickel, B.A., and Beck, M.W., 2021, Rigorously valuing the impact of projected coral reef degradation on coastal hazard risk in Florida: U.S. Geological Survey Open-File Report 2021–1055, 27 p., https://doi.org/10.3133/ofr20211055

Aerial view of Florida and Puerto Rico and the U.S. Virgin Islands to show where data was collected.

Public domain.

U.S. Geological Survey Data Releases

Cumming, K.A., Cole, A.D., Graves, S.H., Storlazzi, C.D., Reguero, B.G., Viehman, T.S., Shope, J.B., and Gaido L., C., Nickel, B.A., and Beck, M.W., 2021, Projected flooding extents and depths based on 10-, 50-, 100-, and 500-year wave-energy return periods for the State of Florida and the Commonwealth of Puerto Rico before and after Hurricanes Irma and Maria due to the storms' damage to the coral reefs: U.S. Geological Survey data release, https://doi.org/10.5066/P9EHOBKO.

Cumming, K.A., Cole, A.D., Storlazzi, C.D., Reguero, B.G., Shope, J.B., Gaido L., C., Viehman, T.S., Nickel, B.A., and Beck, M.W., 2021, Projected flooding extents and depths based on 10-, 50-, 100-, and 500-year wave-energy return periods for the State of Florida, the Commonwealth of Puerto Rico, and the Territory of the U.S. Virgin Islands for current and potentially restored coral reefs: U.S. Geological Survey data release, https://doi.org/10.5066/P9ZQKZR9.

Cumming, K.A., Cole, A.D., Arsenault, S.R., Fehr, Z.W., Storlazzi, C.D., Reguero, B.G., Yates, K.K., Shope, J.B., Gaido L., C., Zawada, D.G., Nickel, B.A., and Beck, M.W., 2021, Projected flooding extents and depths based on 10-, 50-, 100-, and 500-year wave-energy return periods for the State of Florida with and without projected coral reef degradation: U.S. Geological Survey data release, https://doi.org/10.5066/P9D9LDEP.

Video Transcript

View audio described version.

The increasing risk of flooding along our coasts is driven by climate change, development and habitat loss.

Powerful climate-fueled hurricanes such as Irma and Maria in 2017 caused significant damage to coastal communities in Florida and Puerto Rico, not just to infrastructure but to natural barriers such as coral reefs, which help to dissipate wave energy before they flood coastlines.

Three new reports from the U.S. Geological Survey, the University of California and the National Oceanic and Atmospheric Administration quantitatively assess how coral reefs damaged by those hurricanes increased flood risk significantly, to the tune of hundreds of millions of dollars.

The reports also assess how, in the absence of restoration, coral reefs in Florida and Puerto Rico will continue to decline, further increasing the risk of flooding.

But the reports find reason for hope: Coral reef restoration across Florida and Puerto Rico could prevent the loss of more than $270 million annually from flooding.

By working with nature, the reports conclude, we can reduce both present and future risks to coastal communities and save coral reef ecosystems at the same time.

Peter Pearsall, USGS

(Some content used with permission)