In the Philippines, Mangroves Are a Valuable Flood Defense

WASHINGTON, Aug. 8 -- The Nature Conservancy issued the following news release:

Climate change and coastal development are increasing the risks to people and property from flooding across the globe. A new study released today by the WAVES Program, led by the World Bank, quantitatively values the benefits provided by mangroves across the Philippines and finds that they reduce the damage from flooding to people and property by 25 percent annually. These results are summarized in a new report and policy brief , which follow rigorous approaches used in the engineering and insurance sectors to value the national services and benefits provided by nature.

The Philippines is among the most vulnerable countries in the world to flood damage from typhoons and extreme events: in 2013, Typhoon Haiyan alone caused more than 6,000 deaths and over US $2 billion in damages. Philippine coasts have a powerful natural defense: their mangroves. Many coastal habitats, including mangroves, coral reefs and salt marshes, can significantly reduce flooding and erosion, and thus protect people and property from the damages caused by storms, sea level rise and king tides. The aerial roots of mangroves retain sediments and prevent erosion, while the roots, trunks and canopy reduce the force of oncoming waves and storm surge and thus reduce flooding.

But mangroves are threatened by habitat degradation and destruction, in part because the economic value of their benefits and services is not measured, and thus not fully accounted for in policy and management decisions. Better valuations of the protective services of these coastal habitats can ensure that they are recognized and protected. This is the mission of the Global WAVES program, which promotes natural capital accounting to measure and value the services provided by nature. The Philippines is one of the seven countries partnering with WAVES to develop national capital accounts.

A team led by The Nature Conservancy and IHCantabria for the World Bank WAVES program valued the coastal protection provided by mangroves in the Philippines, and identified where these natural coastal defenses provide the greatest protection benefits. The team found that without mangroves, flooding and damages to people, property and infrastructure would increase annually by approximately 25%. Across the Philippines, mangroves reduce flooding to 613,000 people annually, 23% of whom live below the poverty line. Mangroves also avert more than US $1 billion in damages to residential and industrial property. If mangroves were restored to their 1950 distribution, there would be additional benefits to 267,000 people annually, including 61,000 people below poverty, and an additional US $450 million in annual averted damages. Mangroves provide the most significant benefits for the most frequent storms (e.g., the 1 in 10 year storm) but even for extreme, 1-in-50 year events, mangroves avert more than US $1.7 billion in damages.

Beyond the numbers, this work has far reaching consequences.

"This study demonstrates that the protection benefits of mangroves and other coastal habitats can be quantitatively measured and valued, and that these benefits are incredibly important," says Inigo Losada, Director of Research, IHCantabria. "Mangrove conservation and restoration can be an important part of the solution for reducing coastal flood risks and this work identifies where mangroves provide the greatest benefits to the people of the Philippines" says Michael W. Beck, Lead Marine Scientist, The Nature Conservancy.

"By valuing these coastal protection benefits in terms used by finance and development decision-makers (e.g., annual expected benefits), these results can be readily used alongside common metrics of national economic accounting, and can inform risk reduction, development and environmental conservation decisions in the Philippines", according to Socioeconomic Planning Secretary Ernesto Pernia, Director-General, National Economic and Development Authority.

These results have immediate implications for numerous programs in the Philippines, including: the National Greening Program, the Philippines Integrated Area Development, Risk Resilience and Sustainability Program, the Green Climate Fund and People Survival Fund; and the Comprehensive Land Use Plans of local governments. Globally, this work can inform the development of national accounts for natural capital, which can ensure that these ecosystem services are valued and accounted for in policy and management decisions.

This work was produced by a partnership between the WAVES Program, the Environmental Hydraulics Institute of the University of Cantabria, and The Nature Conservancy. The work was primarily funded by the WAVES program, with additional funding from the German Federal Ministry for the Environment Nature Conservation, Building and Nuclear Safety (BMUB) International Climate Initiative, and the Lloyd's Tercentenary Research Foundation.