Storm Surge Reduction by Mangroves
Storm surges pose serious risks to low‑lying coastal areas. This article examines how mangroves reduce surge water levels and wave energy, presents measured and modeled evidence of their effectiveness, and discusses their role alongside engineered defenses in reducing damage, saving lives, and supporting coastal recovery.
Subject Tags
- Mangroves
- Nature-based solutions
- Climate resilience
Executive Summary
Storm surges, driven by high winds and low atmospheric pressure during tropical cyclones, cause severe flooding, loss of life, and damage to infrastructure in low‑lying coastal areas. Climate change is expected to exacerbate these risks through rising sea levels and potentially stronger cyclones. Mangroves can help reduce storm surge impacts by slowing water flow and attenuating surface waves, functioning as natural coastal defenses either alone or in combination with engineered structures and early warning systems. Measured storm surge reductions through mangroves range from 5 to 50 centimeters per kilometer of mangrove width, while wave energy can be reduced by more than 75% over one kilometer of forest. Although direct measurements are limited due to monitoring challenges during extreme events, numerical models provide valuable insights into surge dynamics, showing that mangroves are especially effective against fast‑moving surges and that the greatest reductions often occur near the seaward edge. The article also highlights remaining knowledge gaps, including the influence of mangrove density, species composition, and forest structure. By reducing surge height and wave energy, mangroves can save lives, limit infrastructure damage, and aid post‑disaster recovery, underscoring their importance for coastal risk reduction and resilience planning.
Citation
McIvor, A. L., Spencer, T., Möller, I., & Spalding, M. (2012). Storm surge reduction by mangroves. The Nature Conservancy and Wetlands International.
TNC Authors
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Mark Spalding
Senior Marine Scientist • Protect Oceans, Lands and Waters
The Nature Conservancy
Email: mspalding@tnc.org