A recent study from the University of California found 3100 km of at-risk coastline partially protected by natural defences, such as coral reefs. By making use of computer models, the study was able to estimate the economic value coral reefs provide as coastal flood defences.
‘High-value reefs’ in Florida and Hawaii provide $1 million per kilometre of flood protection each year
The presence of coral reefs was found to help prevent coastal flooding stretching even further inshore. This is achieved by coral reefs acting as wave energy attenuators, capturing the energy from the incoming waves. The study estimated that, annually, coral reefs provide $1.8 billion in risk reduction to the USA. The study was also able to show which areas of coastline benefit the most from coral reefs. So called ‘high-value reefs’ are found in Florida and Hawaii, and provide $1 million per kilometre of flood protection each year.
However, vertical erosion of these natural protective structures means the threat posed by the ocean continues to escalate. Erosion of one metre of coral reef would mean a 23% increase in areas classified as flood zones. If flooding were to occur, an additional 53 800 people would be affected, with costs exceeding $5.3 billion in damages.
By placing economic value on existing natural infrastructure, the study raises awareness of the importance for ecosystem management. Enticing investment into coral reefs would benefit not only the ecosystems themselves, but also the people they protect. Identifying areas that would significantly benefit from coastal protection means time and money can be better invested into effective flood defences.