The natural environment can provide protection against tsunamis, and environmental destruction to make way for development can raise the tsunami risk of coastal communities. Tropical coastal ecosystems have sophisticated natural insurance mechanisms to help them survive the storm waves of typhoons and tsunamis such as coral reefs being equivalent of natural breakwaters causing waves to break offshore and allowing them to dissipate most of their destructive energy before reaching the shore.
Mangrove forests also act as natural shock absorbers, “soaking up destructive wave energy and buffering against erosion”. Systems of marshes, tidal inlets and mangrove channels also help limit the extent of inundation by floodwaters and enable flood waters to drain quickly.
Places that had healthy coral reefs and intact mangroves were far less badly hit than places where the reefs had been damaged and the mangroves ripped out and replaced by beachfront hotels and prawn farms during 2004 Tsunami.
However, there has been widespread destruction of natural coastal habitats to make way for urban development, population growth, industry, aquaculture, agriculture and tourism.
The World Wildlife Fund (WWF, http://www.worldwildlife.org) has recommended that tsunami mitigation strategies take into account:
- Rehabilitation and restoration of degraded coastal ecosystems that help protect from storm waves, especially coastal marshes and forests, mangroves and coral reefs.
- Adoption of integrated coastal zone management, including zoning and mandatory coastal setback. For example, hotels should not be built within a safety zone from the high tide mark.
- Strict enforcement of land and coastal-use planning and policies, including natural disaster risk assessments.
- Implementation of incentives to ensure that sensitive facilities are built away from high risk areas.
- Risk assessment that helps reduce the vulnerability of coastal development.