Social and economic benefits of coral reef restoration: Puerto Rico 2

Coral reef restoration can yield significant flood reduction benefits. These natural defenses were damaged in the 2017 hurricanes; their recovery would reduce the risks of further storm damages to nature, people and property.

The coastal protection benefits of coral reefs and other natural defenses are not usually assessed in the same rigorous, economic terms as artificial defenses and therefore often not considered as an option for hazard management projects. Coral reefs act like submerged breakwaters by breaking waves and dissipating their energy offshore before they flood coastal properties and communities. The restoration of coral reefs can reduce flood risks by decreasing the exposure of coastal communities to storms. In 2017, Hurricanes Irma and Maria caused significant damage to coral reefs across Puerto Rico.

The benefits of reef restoration were assessed across 552 km of the Puerto Rican coastline. Coral reef restoration could provide Puerto Rico with more than $42 million in flood protection benefits annually. Reef restoration could reduce direct flood damages to public and private property worth more than $14 million annually and help avert other costs to livelihoods worth an additional $28 million.  If these restoration projects were considered as a 50-year infrastructure investment, their present value in 2020 dollars would exceed $2.5 billion.

These are not ‘back of the envelope’ numbers. Coastal flood risk was assessed using sophisticated hydrodynamic models.  Flood risk maps were developed to identify the extent and depth of flooding that would occur across a range of storms from common to catastrophic events with current coral reefs and with coral reef restoration. These flood risk maps were combined with the latest information from the U.S. Census Bureau and the U.S. Federal Emergency Management Agency to identify people and properties at current risk and who could benefit from reef restoration.

Rigorously valuing the benefits of coral reef restoration is a key step toward mobilizing resources to protect them. These results can inform hazard mitigation, infrastructure, and disaster recovery decisions, which is particularly critical following the 2017 hurricanes that damaged many reefs.

The benefits of reef restoration across Puerto Rico.  The map identifies where reef restoration can provide the greatest annual reductions in flood risk. The size of the circles indicates the decrease in annual expected economic damages per kilometer of coastline.  There are many benefits of reef restoration around San Juan; this area is highlighted in the figure on the cover page.

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