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Geography conspires against Bangladesh.

As the deadly cyclone brewed in the Bay of Bengal last week, meteorologists succeeded in providing the citizens of Bangladesh a few days warning -- enough time for millions of people to evacuate from lowland areas and islands in the country's eastern reaches. Yet precious hours of warning could not make up for the country's flood-prone geography and overpopulation, twin problems that elevated the disaster to epic proportions.

"The geography of the coast along the northern Bay of Bengal is the worst place in the world for typhoons to hit," says Robert Beard, a meteorologist at the U.S. Joint Typhoon Warning Center, located in Guam.

Situated at the mouth of the Ganges, Bangladesh is made largely of low-lying floodplains and deltas. Some one-third of the country lies less than 20 feet above sea level. Because of the river sediments deposited by the Ganges, the seafloor at the northern Bay of Bengal slopes very gradually away from the shore -- a factor that combines with the shape of the coastline to funnel water inland up river channels during a cyclone, says Beard.

Packing sustained winds of greater than 155 miles per hour, last week's storm pushed a mountain of water more than 18-feet high toward the coastline, says meteorologist Frank H. Wells of the warning center. This so-called storm surge formed when wind friction built up a hill of water ahead of the cyclone. Waves on top of the surge may have crested 30 feet higher, says meteorologist Paul Knight of Pennsylvania State University in University Park.

Because of Bangladesh's flat topography, the surge traveled far inland, combining with rainwater to cause severe flooding. In a tragic testimony to the water's power, the body of a man turned up 12 miles inland from his village, according to David Fredrick, Bangladesh desk officer for the U.S. Agency for International Development in Washington, D.C.

The cyclone intensified as it landed on April 30, making it particularly destructive, says Knight. If it had hit the U.S. coast, a storm of such magnitude would classify as a force-5 hurricane. The most recent such U.S. storm was Camille in 1969. Though called by different names, cyclones in the Indian Ocean, hurricanes in the Atlantic and typhoons in the Pacific all represent the same types of rotating storms, generated over warm tropical waters.

Meteorologists in Bangladesh forecasted the storm's path with enough time for the country to evacuate 3 million people, according to a spokesperson for the Bangladesh embassy in Washington, D.C. Still, the evacuation efforts could not reach remote islands, where many people lacked radios and received no advance warning.

With reports of more than 100,000 deaths, the recent storm classifies as the most deadly to hit Bangladesh since a slightly weaker cyclone in 1970, which killed an estimated 500,000 people. The difference in death tolls demonstrates the effectiveness of the early warning and evacuation system, instituted after the last storm, says Fredrick.

Yet even those gains could not prevent a tragic loss of life, due in part to the overpopulation that forces people to settle on dangerous islands and lowlands, says Kirk Talbott of the World Resources Institute in Washington, D.C. Only the size of Wisconsin, Bangladesh currently holds 115 million people, nearly half the size of the U.S. population.
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Title Annotation:flood-prone geography and overpopulation make cyclones especially deadly
Author:Monastersky, Richard
Publication:Science News
Date:May 11, 1991
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