Wednesday, December 27, 2006

Natural Flood Barriers May Increase Danger of Flooding

This is not the only case of a perceived solution actually creating more of a problem and it reminds us once again, of the importance of allowing all of the ideas to be on the table, with solid representation, before public leadership commits pulic money to a course that may not work.

This, unfortunately, is what is happening in Sacramento, the most flood threatened major city in the country, where local public leadership appears to have taken the Auburn Dam off the table and the small voices heard in its defense, such as ours, the Auburn Dam Council, Sacramento County Taxpayers League, and a few political leaders, sadly watch as the most effective method of preventing large scale flooding is bypassed in favor of settling for the 200 year level of flood protection increased levees might add instead of the 500 year level the dam would give us.

None of us wants to see our community the subject of some future report of how failing to act on the obvious solution created a larger problem.

Andrew Baird: False hopes and natural disasters
By Andrew Baird -
Published 12:00 am PST Wednesday, December 27, 2006

TOWNSVILLE, Australia -- Since the Indian Ocean tsunami two years ago today that killed more than 200,000 people, governments, donors and experts have embraced the idea that healthy mangrove forests and coral reefs could reduce the death toll from a giant wave.

Former President Bill Clinton, in his role as the United Nations special envoy for tsunami recovery, recently endorsed a program that will allocate $62 million to preserve such natural barriers in 12 Asian and African countries.

But the $62 million question is, will these barriers work? Research suggests that the level of protection offered by greenbelts has been exaggerated. And by diverting resources from more effective measures like education campaigns and evacuation plans to well-meaning but misguided reforestation, we may even contribute to a greater loss of life in future tsunamis.

There have been few scientific studies about the protective role of coastal vegetation. And while one study did suggest that a shield of mangrove forest managed to reduce tsunami damage in three villages in Tamil Nadu State in India, the forest was not the only difference between these coastal villages and those nearby that suffered major destruction.

Indeed, when my colleagues and I re-analyzed the data, we found no relationship between the death toll in each village and the area of forest in front of each one.
What actually saved these villages was being further from the coast or built on relatively high land. It was only a coincidence that they also had more forest between themselves and the ocean (of course, the further a village is from the coast, the greater potential area of forest).

Indeed, a recent paper in the journal Natural Hazards that surveyed more than 50 sites in affected regions found that coastal vegetation did not reduce tsunami damage, and that damage was actually greater in areas fronted by coral reefs.