Do bay of bengal cyclones have to be so deadly

Officials estimate that more than 100,000 people perished from tropical cyclone Nargis that hit Myanmar on May 2, 2008. Ninety-five percent of buildings in the coastal region were destroyed by the 12-foot (3.7-m) high storm surge, and more than a million were made homeless and without access to electricity, clean water, or medical care for many months following the disaster. When Cyclone Nargis blew into coastal Myanmar on May 2, it was unfortunately not the first time in recent years that a cyclone has extracted a huge toll on the generally poor, coastal residents of the region.

Bangladesh and the recently devastated coastal Myanmar are densely populated, low-lying regions mostly at or near sea level at the head of the Bay of Bengal. They are delta environments, built where the Ganges, Brahmaputra, and Irrawaddy Rivers drop their sediment eroded from the Himalaya Mountains. These areas sit directly in the path of many Bay of Bengal tropical cyclones (another name for a hurricane), and have been hit by seven of the 10 deadliest hurricane disasters in recorded history.

On November 12 and 13, 1970, a category 3 storm known as the Bhola cyclone hit Bangladesh with 115 mph (184 kph) winds, and a 23-foot (7-m)

high storm surge that struck at the astronomically high tides of a full moon. The devastating result caused 500,000 human deaths and half a million farm animals perished. The death toll is hard to estimate in this rural region, with estimates ranging from 300,000 to 1 million people lost in this one storm alone. Most perished from flooding associated with the storm surge that covered most of the deltaic islands on the Ganges River. Again in 1990 another cyclone hit the same area, this time with a 20-foot (6-m) storm surge and 145-mile-per-hour (232 km/hr) winds, killing another 140,000 people and another half-million farm animals. In November 2007 Bangladesh was hit by a powerful category 5 cyclone, with 150 mph (240 km/hr) winds, and was inundated with a 20-foot (6-m) high storm surge. Since the 1990 storm, the area had a better warning system in place, so many more people evacuated low-lying areas before the storm. Still, it is estimated that 5,000-10,000 people perished during Typhoon Sidr, most from the effects of the storm surge.

Why do so many continue to move to areas prone to repeated strikes by tropical cyclones? Bangladesh and coastal Myanmar are overpopulated regions with densities 50 times as great as that of farmlands typical of the midwestern United States. Bangladesh's per capita income is only $200, whereas Myanmar's is $1,900. The delta regions of Bangladesh and Myanmar are the respective country's most fertile. Farmers can expect to yield three rice crops per year, making them attractive place to live despite the risk of storm surges. With the continued population explosion in coastal regions of the Bay of Bengal and the paucity of fertile soils in higher grounds, the delta regions continue to be farmed by millions and continue to be hit by tropical cyclones like the 1970, 1990, 2007, and 2008 disasters. The lower death toll in the 2007 category 5 cyclone in Bangladesh compared with similar earlier storms demonstrates that investment in better warning systems and planned evacuations can save tens to hundreds of thousands of lives. The government of Myanmar has not opened itself to international aid, advice on emergency planning, and better protection of its population.

FURTHER READING

Davis, R., and D. Fitzgerald. Beaches and

Coasts. Malden, Mass.: Blackwell, 2004. Kusky, T. M. The Coast: Hazardous Interactions within the Coastal Environment. New York: Facts On File, 2008.

can develop along these polar fronts, and winds that blow in opposite directions to the north and south of the low set up a cyclonic (counterclockwise in the Northern Hemisphere) wind shear that can cause a wavelike kink to develop in the front. This kink, an incipient cyclone, includes (in the Northern Hemisphere) a cold front that pushes southward and counterclockwise and a warm front that spins counterclockwise and moves to the north. A comma-shaped band of precipitation develops around a central low that develops where the cold and warm fronts meet, and the whole system will migrate east or northeast along the polar front, driven by high-altitude steering winds.

The energy for extratropical cyclones to develop and intensify comes from warm air rising and cold air sinking, transforming potential energy into kinetic energy. Condensation also provides extra energy as latent heat. These storms can intensify rapidly and are especially strong when the cold front overtakes the warm front, occluding the system. The point at which the cold front, warm front, and occluded front meet is known as a triple point. It is often the site of the formation of a new secondary low-pressure system to the east or southeast of the main front. This new secondary low often develops into a new cyclonic system and moves eastward or northeastward, and may become the stronger of the two lows. In the case of New England's northeasters, the secondary lows typically develop off the coast of the Carolinas or Virginia, then rapidly intensify as they move up the coast, bringing cyclonic winds and moisture in from the northeast off the Atlantic Ocean.

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Responses

  • lena
    Do the deepresaions in bay of bebgal have warm,cold front?
    3 years ago

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