Tsunami Barriers

Tsunami Barriers

The devastating tsunamis in Asia showed Mother Nature at her most fierce. But according to one scientist, human activities may have contributed to the waves' awesome power.


Making tsunamis worse. I'm Bob Hirshon and this is Science Update.

Humans may have unwittingly aggravated some of the damage by the recent tsunamis. That's according to Edward Barbier, a professor of economics at the University of Wyoming.

For years, he's tracked the destruction of mangrove forests and coral reefs on the Asian coast. These natural flood barriers have been cleared out for everything from shrimp farms to tourist resorts.


Mangroves might not have stopped some of the worst direct impacts of the tsunami. But simply the spread of the tsunami, and the flow of the coastal waters, and the flood and the surge of water that occurred could have been mitigated somewhat by having more mangrove and natural protection.

He says the loss of these ecosystems has also depleted the area's natural resources, and destroyed breeding grounds for fish that locals subsist on. I'm Bob Hirshon for AAAS, the Science Society.

Making Sense of the Research

This is a perfect example of human activities causing unintended consequences. Humans have radically changed the face of the entire planet to serve our own purposes. Unfortunately, some of the changes we make can come back to haunt us.

The changes usually start from some short-term need. For example, in Southeast Asia, two of the biggest industries are seafood and tourism. Since shrimp grow best in unobstructed areas near the shore, many mangrove forests have been clear-cut to make room for shrimp farms. Similarly, to meet the growing demand for tourist resorts, many developers have made their own swimming areas by removing mangroves and coral reefs. The end result is that the mangrove forests along the Gulf of Thailand and the Indian Ocean have been cut in half since the 1960's.

As it turns out, some of the areas hardest-hit by the tsunami are those that have lost these natural barriers. It's impossible to know for sure how much worse the impact of the tsunami was in these areas. But it's known that natural barriers like mangroves and coral reefs can cushion the blow of incoming waves.

What's the solution? Obviously, reducing the loss of these natural barriers is recommended. And although natural barriers like coral reefs can't be restored once they're gone, they can be replaced by artificial reefs. This is going on off the coast of Virginia, where out-of-service New York City subway cars are being pushed into the sea to form an artificial reef.

As far as the economy is concerned, Barbier notes that clearing out coastal areas isn't good for everyone. Although large seafood manufacturers and resort industries score big by clearing out mangroves and reefs, the environmental damage hurts the native fish populations, on which local people subsist. So preserving coastal environment may protect both the livelihood and the lives of ordinary Asians.

Now try and answer these questions:

  1. Why are mangroves and coral reefs being destroyed in Southeast Asia?
  2. How might this have worsened the impact of the tsunami?
  3. How do you think powerful industries, like the shrimp and tourism industry, can be discouraged from altering these coastal areas? Why might the government be reluctant to pass harsh laws restricting development?
  4. What other studies might be done to determine if the mangrove and coral reef loss really made the tsunami damage worse?

For Educators

The Mangrove Action Project is a non-profit conservation group dedicated to preserving mangrove forests worldwide.

You can see mangroves and how they protect coastlines in the following short video from the National Park Service BioBlitz in Biscayne Bay, Florida.

Related Resources

2010 BioBlitz BobCast 4: Mangroves
K-12 | Video
Science of a Tsunami
6-12 | Video
Adolescent Anxiety
6-12 | Audio

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