Mangroves protected villages and reduced death toll during Indian super cyclone

Background

While protection against storm damage is discussed as an ecosystem service of mangroves, there is debate about whether there is sufficient evidence for these claims. Multiple studies on this topic use small sample sizes and have a lack of controls for confounding factors. However, quality research exists that effectively demonstrates mangroves’ ability to protect coastal communities from tropical storm surge. Thus, it is necessary that future studies focusing on mangroves’ protective capabilities from tropical storms follow higher research standards to effectively provide evidence for this ecosystem service.

Goals and Methods

The authors analyzed the super cyclone that struck the Kendrapada District in Odisha, India in October 1999. They focused on mortality and socioeconomic data from 409 villages that historically had mangroves between them and the coast, testing whether these villages had the same average number of deaths during the storm as villages with narrower or no mangroves. The authors estimated the change in mangrove area between 1944 and 1999 from topographical maps and satellite data, and used GIS to measure mangrove width in 1999.

Conclusions and Takeaways

Despite mangrove area shrinking over time (5.1 km in 1944 to 1.2 km in 1999), mangroves significantly reduced the number of deaths in villages within 10 km of the coast during the October 1999 cyclone. The authors estimate that villages within 10 km of the coast would have experienced 1.72 additional deaths per village if there were no mangroves. Additionally, an early warning system saved more lives (5.84 lives per village) than the remaining mangroves (0.0148 lives saved per hectare of remaining mangrove), showing that mangroves are only one element of an effective tropical storm protection strategy.