Mangroves protected villages and reduced death toll during Indian super cyclone

Study Number:

21

Author:

S. Das and J. R. Vincent

Abstract:

Protection against coastal disasters has been identified as an important service of mangrove ecosystems. Empirical studies on this service have been criticized, however, for using small samples and inadequately controlling for confounding factors. We used data on several hundred villages to test the impact of mangroves on human deaths during a 1999 super cyclone that struck Orissa, India. We found that villages with wider mangroves between them and the coast experienced significantly fewer deaths than ones with narrower or no mangroves. This finding was robust to the inclusion of a wide range of other variables to our statistical model, including controls for the historical extent of mangroves. Although mangroves evidently saved fewer lives than an early warning issued by the government, the retention of remaining mangroves in Orissa is economically justified even without considering the many benefits they provide to human society besides storm-protection services.

Main Results and Conclusions:

• The significance of mangrove habitat for protection against storm surges is explained: “We measured mangrove width as the distance between the coast and the interior boundary of the forest along the shortest distance from each village to the coast. Average 1999 width across the 409 villages was 1.2km down from 5.1 in 1944…The total number of deaths across the villages was 256, for an average of 0.63 (average village population = 1,002). The maximum was 21, and 307 villages had no deaths. The simple correlation of number of deaths with 1999 mangrove width was negative and significant (r = -0.13, P <0.01; Fig. 2).