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Saturday, October 26, 2013

Cyclones and their mitigation

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Cyclones are extremely disastrous hazards that originate in seawater. These are usually followed by rains and wind of very high speed. In fact, these are atmospheric disasters that occur in costal areas like coastal regions of Bangla Desh and India. Cyclones are called by different names in different parts of the world. Cyclones of eastern U.S.A. and Caribbean region are called as hurricanes and the same in the North Pacific Oceans are called typhoons. Local storms are called tornados.
Where do cyclones occur?
Cyclones occur in a certain atmospheric area from where they spread in different directions. These usually extend vertically up to 12 to 14 km and horizontally up to 150 to 1000 km. These normally occur during different months of a year like April- may or September- November. They mainly affect the coastal areas located along the Bay of Bengal and Arabian Sea. Orissa, Andhra Pradesh, West Bengal, Gujarat, Kerela, Karnataka and Maharastra are states of India worst affected by Tropical Cyclones.
How does a cyclone originate?
As sea-water is heated up, it turns into vapour which rises up with the warm air. Thus, a depression or the area of low air pressure is created which is called as the centre or the eye of the storm. When this condition of very low atmospheric pressure is combined with forces of strong speedy wind (with a speed ranging from 150 to 400 km per hour) on sea surface, it causes unusual rise of sea-waves called as Tidal Surges. The tidal surges cumulatively give birth to a cyclone.
What are the impacts of a cyclone?
Cyclones have various types’ of serious impacts following on life, property and environment. They cause
severe damages to  ships and goods loaded on them. They kill human beings travelling through those ships.  A lot of oil is spilled on the surface of sea-water which damages ocean-ecosystems. They cause
heavy damages to land by depositing salt etc.  Besides this, they cause heavy damages to houses, other building, agricultural property, and kill humans and cattle on large scales.
Cyclones disseminate a number of viral and bacterial diseases like cholera, diarrhoea, hepatitis etc.
They damage coral reefs and mangroves that are habitats of large varieties of animals.
They enforce people to evacuate their habitats. Some             Examples of some devastating Super Cyclones are -
(a)    A Super cyclone hit the sea coast of Orissa on September 29, 1971 and caused deaths of 10,000 to 25,000 people.
(b)   A Super cyclone hit the sea coast of Bangladesh on June 10, 1991 and caused deaths of 125,720 persons besides heavy losses to cattle and other property.
(c)    The Eastern India Super Cyclone occurred on Oct. 29, 1999 and caused deaths of about 9000 persons.
(d)   Cyclone Katrina occurred from Aug. 23—30, 2005, in New Orleans, Louisiana, Southern USA, and caused deaths upto1000.
Management and Mitigation of cyclones
Disasters due to cyclones can be prevented by adopting safety measures and by constructing barriers. Some important measures for mitigation of cyclones are mentioned below-
·         Plantation of green belts along the coastal line in a scientific interweaving pattern can reduce the hazard due to a cyclone.
·         Wide buffer zones of forests should be managed properly along the coastal line so that cyclone may not run freely to penetrate inland.
·         Meteorological records of wind speed and directions should be kept properly so as to predict for future cyclones and to make advanced preparations. In this regard hazard mapping is very important.
  • Policies should be made to regulate land use and enforcement of building codes.
  • Vulnerable areas should be reserved for parks, grazing grounds or play grounds.
·         Buildings in coastal areas should have high engineering inputs. Traditional homes should be improved by building in disaster resistant features so that they can withstand cyclones with moderate speed.
  • Building meant for storing food supply should be protected against winds and water.
·         Arrangement of early warning systems, construction of concrete walls along coast line, organization of action groups and rescue squads etc. are some other important measures to mitigate cyclones.

Cyclones are natural events that can neither be wished away nor prevented. What actually makes these hazards turn in to disasters is the vulnerability of the people , their means of livelihood and the fragility of infrastructure. The Indian Sub-continent is the worst affected part in the world as far as loss of lives is concerned though more severe cyclones do occur in other parts of the world and financial losses are much more elsewhere.
High population density, better employment opportunities and economic compulsions encourage people to occupy, areas, which are susceptible to cyclones, saline ingress and flooding. Inadequacy of infrastructure adds to their vulnerability. Traditional mechanisms of disaster management have been the mainstay for these people to counter hazards, but during major disasters these systems are found wanting. Though human communities have a natural tendency to face hazards by joining hands, they usually fail to generate the desired strength because of unsystematic and careless approaches. Thanks to the careful efforts of the meteorological department and the attention of the media that people get time to save themselves and their property up to the possible extent. You too, should device a project on cyclone mitigation through deep study and under the directions of your teacher.  
Key Words : cyclone, hazard, monitoring, mitigation

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