Coral reefs and flood prevention

By Danielle Moloney 

Edited by Sara Gagliardi 


For decades, coral reefs have been an important contributor to the livelihood of coastal communities. Whether it be through fishing, tourism, or recreation, these colorful structures play a role in the daily lives of many people across the globe. They also have a less obvious role: coastal flood protection. A new study from the University of California Santa Cruz and the US Geological Survey outlines the importance of coral reefs when it comes to protecting coastal communities in the United States. A significant source of protection provided by corals is their ability to decrease flooding in the wake of storms. The research aimed to put a monetary value on the protection that coral reefs provide, as well as categorize where the protection occurs. The findings of this research have important implications for how policy can most effectively conserve corals to maximize the protection they can provide.  

A photo shows coastal flooding in Florida, in the aftermath of hurricane Irma in 2017. Coastal flooding caused by severe storms has increased in intensity in recent years, as global climate change makes storms more erratic and damaging. Photo courtesy of WJCT news. 

One small meter for coral, one giant meter for mankind 

Using a complex computer model of storms and waves, combined with economic, social, and mapping tools, to determine the value that reefs provide. This fine-scale modelling even goes as far as taking ‘critical infrastructure’ into account- such as hospitals, fire stations, roads, and powerplants- that would be impacted in the event of a coastal flood. These types of measurements are very useful to agencies who determine how, where, and when to protect reefs, based on the value that they provide. These targeted protections can help save lives during storms, decrease economic losses, and attain coral conservation goals. This study specifically focused on three categories of reef protection: people, infrastructure, and economic activity. The numbers that the authors came up with are staggering: reefs offer over $1.8 billion USD in annual flood protection to coastal communities in the US. 

Of the computer modelling process, lead author of the study, Borja Reguero, said: “Achieving this kind of definition required a complex modeling strategy to account for all the processes relevant in coral reef environments, which are significantly different to those driving flooding in other coastlines. The approach can also be applied to other ecosystems, and it now allows assessing the impacts of future changes in storms or sea level rise too.” 

A map shows projected flooding in the event of a category 3 hurricane hitting a Florida neighborhood in 2033.  Photo courtesy of EcoWatch. 

Another metric the researchers used to quantify the value reefs provide in the event of coastal storms was a scenario in which the top one meter of reef height was lost. The computer model that the researchers used for this project included the ability to project fine-scale (very detailed) modelling of floods both with and without the top one meter of coastal reefs. If the top one meter of reef height was lost, 90% more coastal property would be affected by flooding, increasing damage costs by a whopping $5.3 billion USD.   The study also assessed how the loss of reefs would impact the 100 year flood zone. The 100 year flood zone is a term that describes the occurrence and severity of floods by referring to the area of land that has a 1% chance, or 1-in-100 chance, of flooding in any given year. These damages would increase the 100-year flooding zones by 23%, impacting 53,800 more people (a 62% increase from those who would be otherwise affected).

Furthermore, the research found that there are 200 miles, or 325 kilometers, of high-value reefs across the United States (most of which are located in Florida and Hawaii). These reefs provide a lot of bang for your buck, clocking in at a value of $1.6 million USD per mile for their flood protection alone. 


Rising sea levels driven by global climate change continue to intensify coastal flooding, making research focused on how to protect coastal communities more important than ever. The findings of this study serve to reinforce the importance of protecting coral reefs as the valuable natural resource that they are. Author Reguero reiterates how this research exemplifies the value of reefs as protectors of coastal communities, while also highlighting economic benefits that often catch the attention of, and drive, policy decision-making. Furthermore, the complex computer modelling used for this project may serve as a helpful tool to assess other natural resources for their protective value. 

Please contact the author with any questions:

Photo courtesy of The Nature Conservancy.

Reguero, B.G., Storlazzi, C.D., Gibbs, A.E. et al. The value of US coral reefs for flood risk reduction. Nat Sustain (2021).

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