Arguments for protection: disaster mitigation

Natural habitats can buffer against various types of natural disasters. This is particularly important for the poor, who are especially vulnerable to natural disasters such as floods and storms.

Preventing flood damage

One of the most significant social and economic benefits provided by wetlands is flood mitigation and control.

Upstream wetlands can store water from heavy rainfalls, thereby preventing possible flooding downstream. Downstream wetlands can additionally slow floodwaters and provide space for water overflowing from rivers, thereby reducing a flood’s destructiveness.

The economic value of this is huge. For example, the flood attenuation function of two reserves in Sri Lanka’s Muthurajawela Marsh – located near the country’s most densely populated and economically important urban area – is worth an estimated US$5 million each year.

Despite this, wetlands are often seen as having little or no value. They are routinely drained and converted to agriculture or for human habitation – which has reduced their capacity to protect against flooding. And perversely, the subsequent construction of levees and dams on rivers to control floods has often had the reverse effect.
Child standing in the debris of Hurricane Mitch Tegucigalpa, Honduras.
Child standing in front of home destroyed home by Hurricane Mitch in 1998, Honduras. Natural coastal habitats can provide significant protection from storms.
Wetlands are now being restored in several parts of the world, as part of flood management programmes. However, restoration is not only expensive, but it rarely produces a perfectly re-established ecosystem with fully functioning natural ecological processes.

Clearly, it is much more cost-effective to simply protect wetlands in the first place.

Preventing coastal damage

Mangroves, coral reefs, sand dunes, and other coastal habitats provide significant protection against damage from hurricanes, cyclones, storm surges, and tsunamis. Mangrove forests, for example, can absorb 70-90% of the energy of wind-generated waves, while the protective function of coral reefs is estimated to be worth US$9 billion per year globally.

When these habitats are cleared or destroyed, ocean water can penetrate much further inland, endangering people, homes, farmland, and livelihoods.

The 2004 Indian Ocean tsunami provides a good illustration of this. Coastal communities in South and Southeast Asia that had maintained healthy coastal habitats suffered much less from the tsunami than those with damaged coral reefs and cleared mangroves and coastal vegetation.

With an estimated 60% of the world’s population living within 60 km of a coast, the protection provided by natural coastal habitats clearly makes them worth saving.

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