Coastal Wetlands and Flood Damage Reduction

On the four-year anniversary of Hurricane Sandy, TNC and its partners in the insurance industry and academia released a study that uses high resolution risk industry models and assets data to value the role of wetlands in coastal defense.  The report “Coastal Wetlands and Flood Damage Reduction: Using Risk Industry-based Models to Assess Natural Defenses in the Northeast USA” The results show that natural storm defenses such as coastal wetlands help reduce waves and storm surge, protecting people and property. During Hurricane Sandy, coastal wetlands in the northeast US prevented an estimated $625 million in property damages from flooding across 12 states. In New Jersey alone, wetlands prevented an estimated $425 million in private property damages. In Ocean County, New Jersey, wetlands reduced annual expected losses by 20% on average and over 50% for properties built just feet above sea level.   These results were somewhat surprising, because in many places along the Northeast coast, only thin bands of coastal wetlands remain of the formerly extensive natural storm barriers. Where wetlands do remain, the average damage reduction during Sandy was greater than 10%.

As the likelihood and costs of hurricanes like Sandy continue to increase, coastal communities need a more effective suite of strategies for risk reduction. Coastal wetlands provide a natural defense from flooding and storm surge, but these habitats are being degraded or lost at alarming rates.  This report provides one of the few existing assessments of the economic costs and benefits of the role of coastal wetlands in reducing flood damage to properties. The report shows that coastal wetlands can reduce property damage from storms, and that these protection benefits can be readily incorporated and accounted for in the insurance industry’s risk models. This research will help inform (i) risk reduction and conservation management priorities and (ii) the development of incentives for the conservation and restoration of natural defenses.

Coastal Wetlands Protected People and Property During Hurricane Sandy
Census tracks show the percent change in flood damages that would have occurred during Hurricane Sandy if our coastal wetlands were lost. Dark red areas receive the greatest protection benefits from coastal wetlands.

This work is supported by the Lloyd’s Tercentenary Research Foundation, and was led by the University of California Santa Cruz, The Nature Conservancy, and the Wildlife Conservation Society, in association with Risk Management Solutions and Guy Carpenter and Company, with additional support from the Science for Nature and People Partnership.  This work shows the benefits of collaboration between unlikely partners- conservationists, engineers and insurance risk experts- to identify innovative solutions to reduce coastal risk.  The work was featured prominently in social and traditional media (United Press International), industry trade journals (Insurance Journal, Claims Journal), and science sites (phys.org).