The Global Flood Protection Benefits of Mangroves

The Global Flood Protection Benefits of Mangroves
Mangrove trees grow in coastal saline or brackish water; about 110 species globally are considered mangrove trees.

Menendez et al. 2020

This paper estimates the economic value of mangrove forests for flood mitigation at the highest resolution to-date – for every 20km of mangrove coastline globally. The authors find that mangroves provide over $65 billion in flood protection, and prevent 15 million people from being flooded every year. Loss of mangroves worldwide would cause 29% more land, 28% more people and 9% more property to be damaged each year. About 90% of the flood protection by mangroves is from tropical cyclones whilst 10% is from storms during regular conditions; the benefit from mangroves is greater during more severe storms.

The absolute economic benefit is highest in the USA, China and Taiwan, whilst the economic benefit per $GDP is highest in less economically developed countries, such as Belize, Suriname and Mozambique where the value of mangrove flood protection is greater than 15% of national GDP. In contrast, Vietnam, India and Bangladesh have the most people protected. The authors suggest that value of mangroves for flood protection depends more on the length of coastline they protect than the forest width; this explains, for example, why mangroves protect 4.5x more land in Cuba than in Indonesia, despite the latter having 6.5x more mangrove forest by area.

The high resolution of this analysis means the data can be used to inform prioritisation of mangrove forests for protection and restoration. For example, the most benefit from mangroves in the Philippines is in the central and northern regions where the effects of typhoons are felt most strongly.

Read the paper here.