A wall of water
On May 2, 2008, a Category 4 cyclone named Nargis made landfall in the Ayeyarwady Region of Myanmar. With wind speeds reaching 215 km/h (135 mph), it was a powerful storm, and the wind was not the main killer. Nargis pushed a wall of water—a storm surge between 3.5 and 7 meters high—up to 40 kilometers inland across the low-lying and densely populated delta. The final death toll was at least 138,373 people.
A main reason for the catastrophic loss of life was the absence of a natural barrier. The Irrawaddy Delta was once lined with a dense shield of mangrove forests. These unique ecosystems, with their tangled prop roots and dense vegetation, are remarkably effective at dissipating the energy of waves and storm surges. Scientific models show that just 100 meters of mangrove forest can reduce wave height by up to 66%. Wider belts of forest, several hundred meters across, can significantly reduce the height and extent of flooding from a storm surge. In the aftermath of Nargis, the protective value of the remaining mangroves was clear. Villages sheltered behind healthy mangrove forests suffered far less damage than those left exposed by decades of deforestation.