The New Nation - Internet Edition

Redoy Hassan

Hazard is the broadest term and reflects a potential threat to humans as well as the impact of an event on society and the environment. Similarly coastal hazard is defined as a phenomenon in which it has potentially very dangerous occurrences along, near relating to a cost that is brought about by the interaction between people and nature.

Although coastal areas are varied in topography, climate and vegetation, they are generally dynamic environments. Continental and oceanic processes converge along coasts to produce a landscape that is characteristically capable of rapid change. The impact of hazardous coastal processes is considerable, because many populated areas are located near the coast.

There are different types of coastal hazards such as tropical cyclone, tidal flood, storm surge, tsunami and coastal erosion. Among them the most serious coastal hazard is tropical cyclone for our country, which claim many lives and causes enormous amounts of property damage every year.

Simply tropical cyclone is defined as a cyclone that develops over tropical ocean and has winds up to hurricane's force. More specifically when a storm revolves round a centre, it is termed a cyclone.

Tropical cyclone forms and grows over warm ocean water drawing its energy from latent heat. The earth rotation causes the wind to follow a curved path over the ocean which helps give tropical cyclone its circular appearance. Tropical cyclone forms, maintaining its strength and grows only when it is over ocean water that is approximately 270c. Such warm temperature causes large amounts of water to evaporate, making the air very humid. This warm water requirement account for the existence of the tropical cyclones, seasons which occur generally during a hemisphere's Summer and Autumn. Because water is slow to warm enough for tropical cyclones to occur in the Spring. Tropical cyclone needs more than 270c sea temperature for its initial formation; such as high surface temperature is necessary to produce a steep Laps Rate (The change of atmospheric air temperature with altitude is called the Laps Rate) for maintaining the vertical circulation in a cyclone. This condition is met throughout the year in region of the Bay of Bengal where cyclones are formed mostly near the Andamans.

The magnitude and frequency of tropical cyclone are not affected by human activity. Most tropical cyclones usually occur at latitudes greater than 50 N or 50 S. The cyclones are generated as tropical distances and dissipate as they move over the land. Wind speeds in these storms are grater than 100 km per hour, and the winds blow in a large spiral around a relatively calm center called the eye of the hurricane.

Tropical cyclones, known as typhoons in most of the Pacific Ocean and hurricanes in the Western Hemisphere, cause damage and destruction from high winds; river flooding that results from intense precipitation and usually causes more deaths and destruction than the wind; and storm surges (Wind- driven oceanic water) that are the most lethal aspect of tropical cyclones.

Bangladesh has been affected by tropical cyclones several times. Tropical cyclones of 1948, 1960, 1970, 1991, 1998 and SIDR of 2007 were the most catastrophic cyclones. Tropical cyclones have taken hundreds of thousands of lives in a single storm. A tropical cyclone that struck in the northern Bay of Bengal in Bangladesh in November of 1970 produced a 6-meter rise in the sea. Flooding killed 300,000 people, caused $63 million in crop losses, and destroyed 65 percent of the total fishing capacity of the coastal region.

There are several effects of tropical cyclone in Bangladesh which are as follows-

Most cyclones with storm surge sometime wash over entire offshore island and large areas on the coast.

Astronomical tides in combination with cyclonic surge lead to higher water level and hence serve coastal flooding.

Disruption of human settlement.

Causalities of living beings.

Destroy of vegetation.

Change of land use pattern.

Creates tidal flooding which causes great losses of coastal areas.

Damage of buildings, homes, bridge, roads and other infrastructures.

Ecological disruption of coastal areas.

So, it seems that cyclone causes a great havoc and is usually followed by scarcity of food and outbreak of various diseases such as cholera, dysentery, diarrhea, fever etc which spread all over the affected areas.

In our country people adjust to the tropical cyclone hazard either by doing nothing and bearing the loss or by taking some kind of action to modify potential loss. Bearing the loss is probably the most common individual adjustment.

Attempts to modify potential loss include strengthening the environment with protective structures and land stabilization, and adapting behavior by better land use zoning, evacuation, and warning. Inhabitants in area with a serious tropical cyclone hazard, such as coastal Bangladesh are very much aware of the hazard. In Bangladesh, perception of the cyclone hazard was influenced by people's economic and cultural backgrounds. It was found that the people are not particularly concerned about the hazard, and the three socioeconomic classes perceive the cyclones in the same way.

Although repeatedly devastated by tropical cyclones, coastal areas in Bangladesh do not have an integrated system of private or public adjustment. Although people there are aware of the hazard, the adoption of adjustments is not a function of the frequency of cyclones. Even when shelter is available, people are reluctant to leave their homes. During a 1970 cyclone, approximately 38 % of the people saved their lives by climbing trees, 5% took shelter in a two-story "community center," and 8% remained on top of an embankment designed to protect the land against saltwater intrusion. Thus people saved their lives during that cyclone.

People's attitudes toward cyclonic damage and the possibility of preventing or modifying damage are related to their educational level and their cyclone experience. Public awareness programs in areas likely to experience tropical cyclones should thus be matched to the educational level of the target group. Furthermore, since better-educated people tend to be more positive toward damage prevention, increased attention should be given to the less educated population to counteract their tendency to lack confidence damage-prevention measures. Awareness programs also should be designed differently depending on the area's history of cyclone experience.

However the great loss caused by cyclones can be reduced to a substantial extent. Using modern technologies of weather forecasting (i.e. GIS, Remote Sensing), prior warning can be given to the people who are likely to be affected by the cyclone. The people and domestic animals can be shifted to the cyclone shelters. Moreover, a quick relief, medical treatment and essential medicines should be made available to the affected people just after a terrible cyclone.

Recently the devastating SIDR has passed away with its mighty effects and NARGIS didn't touch Bangladesh. This is the time of cyclones and storms. How much we are prepared to face another mighty Tropical Cyclone?