Cyclone a tropical storm or atmospheric turbulence involving circular motion of winds, occurs in Bangladesh as a natural hazard. The tropics can be regarded as the region lying between 30'N latitude and 30'S latitude. All the tropical seas of the earth with the exception of the south Atlantic and southeast Pacific give birth to deadly atmospheric phenomena known as tropical cyclones. On an average, 80 tropical cyclones are formed every year all over the globe.
The term cyclone is derived from the Greek word 'kyklos' meaning coil of snakes. The British-Indian scientist and meteorologist henry piddington coined the word 'Cyclone' to represent whirling storms expressing sufficiently the tendency to circular motion in his book The Sailor's Horn-book for the Law of Storms, published in 1848. Other meteorologists of the world immediately accepted the term and it is still current today. Satellite pictures of cyclones show that the nomenclature is very appropriate. Technically a cyclone is an area of low pressure where strong winds blow around a centre in an anticlockwise direction in the Northern Hemisphere and a clockwise direction in the Southern Hemisphere. Cyclones occurring in the tropical regions are called tropical cyclones and those occurring elsewhere are called extratropical cyclones.
Tropical cyclones are usually destructive and affect Bangladesh and its adjoining areas. Tropical storms are called hurricanes in the American continent, typhoons in the Far East and cyclones in the South Asian subcontinent. In the West, hurricanes are identified with human names such as Mitchel, Andrew, Carol, Dorothy and Eve. In the South Asian region no such nomenclature is in use. The term 'cyclone' is at times applied to a mid-latitude depression but is now increasingly restricted to a tropical depression of the hurricane type, especially when it occurs in the indian ocean. A cyclone is called Tufan in Bangla, from the Chinese 'Tai-fun'.
Bangladesh is part of the humid tropics, with the himalayas on the north and the funnel-shaped coast touching the bay of bengal on the south. This peculiar geography of Bangladesh brings not only the life-giving monsoons but also catastrophic cyclones, nor'westers, tornadoes and floods. The Bay of Bengal is an ideal breeding ground for tropical cyclones. Cyclones are usually formed in the deep seas and hence their study has been very difficult. It is only with the advent of the Space age that weather satellites have provided valuable information about them. Direct studies of cyclones with aircraft reconnaissance are also being carried out by advanced countries. However, only a beginning has been made in Bangladesh towards the understanding of cyclones.
Classification Cyclones in Bangladesh are presently classified according to their intensity and the following nomenclature is in use: depression (winds upto 62 km/hr), cyclonic storm (winds from 63 to 87 km/hr), severe cyclonic storm (winds from 88 to 118 km/hr) and severe cyclonic storm of hurricane intensity (winds above 118 km/hr).
Formation A tropical cyclone needs more than 27'C sea temperature for its initial formation. Such a high surface temperature is necessary to produce a steep lapse rate for maintaining the vertical circulation in a cyclone. This condition is met throughout the year in regions of the Bay of Bengal where cyclones are formed, mostly near the Andamans. They usually occur at latitudes greater than 5'N or 5'S. It is thought that the Inter-tropical Convergence Zone has something to do with the formation of a cyclone. The Inter-tropical Convergence Zone is the region where winds from the two hemispheres meet near the equator, but its position varies with the season. A cyclone derives its spinning motion from the Coriolis Force arising out of the earth's rotation. This force is virtually zero (0) at the equator. Hence, cyclones do not usually form at the equator. They are formed slightly north of the equator in the Northern Hemisphere, where they can acquire the necessary spin. It is probable that the easterly waves also play some part in the process of cyclone formation.
Among all the atmospheric disturbances, cyclones are the most destructive. The diameter of a cyclone may range from 300 km to 600 km. A cyclone is accompanied by winds with speeds in excess of 118 km/hr, which flow toward the centre of a very strong low pressure. Pressure at the centre of the low may be 50-60 hPa (Hexa Pascal) less than in its outskirts. Cyclones are also accompanied by storm surges. Strong winds bring in enormous amounts of moisture and latent heat toward the centre of the low, which supply the necessary energy to the cyclone. The spiralling winds converge toward the centre of the low pressure where they rise at a tremendous speed.
The most striking feature of a cyclone is its 'eye'. The eye can be seen clearly in satellite pictures in the case of a well-developed cyclone. The eye is small and almost circular; it coincides with the area of lowest pressure and has a diameter ranging from 8 km to 50 km. The eye is warmer than the rest of the storm area. The more violent the storm, the warmer the eye. The winds are very light in the eye, usually not more than 25 to 30 km/hr and rain is practically absent. In contrast, the strongest winds and the heaviest rain occur just outside this central eye.
Wind speed gradually diminishes as one moves away from the region of strongest wind. The main core of the cyclone is circular or nearly circular, having a diameter ranging from 100 km to 800 km. The main cyclone is often accompanied by a long tail having more than one band. The whole thing has a spiral structure, and looks like a comma. The tail may extend up to a few hundred kilometres. The tail usually crosses the land well before the main core of the cyclone and as a result the sky becomes overcast with clouds and rain often sets in before the onset of a cyclone. Such symptoms can serve as a warning for the possible approach of a cyclone.
The right-hand side of a travelling cyclone has more destructive power than its left-hand side. The duration of a cyclone, from the beginning to the end, may range from 7 to 10 days and it may produce 25 cm to 50 cm of rainfall. The life cycle of a cyclone ends soon after the cyclone reaches land ('landfall'), because it is cut off from its moisture source.
Cyclone track Cyclones in their initial stages move at a rate of 5 to 10 km/hr. In their final stage they may move at a rate of 20 to 30 km/hr or even up to 40 km/hr. Cyclones in the Bay of Bengal usually move northwest in the beginning and then curve eastwards. But this pattern is not uniform as seen from the tracks of various cyclones. Cyclones accompanied by heavy rains and sea swells are called storm surges. If this occurs during high tide, the storm surge is reinforced considerably and can rise as high as 12m. This deadly wall of water does most of the damage to life and property.
In cyclone forecasting, it is often assumed that a cyclone follows the direction of the upper atmospheric current. sparrso (Space Research and Remote Sensing Organisation) in collaboration with Dhaka University has undertaken an investigation of the problem and it has been found that there seems to be a steering current for every cyclone, but the level differs from cyclone to cyclone and there does not seem to be any relationship with the intensity of the cyclone. Moreover, the upper atmospheric current is as variable as the tract of the cyclone. SPARRSO has installed the model TYAN for predicting the track of a cyclone based on the climatology of the Bay of Bengal cyclones for the last one hundred years. The model has shown promising results in forecasting a cyclone's movement twenty-four hours ahead of landfall.
Storm surges In addition to the waves associated with winds, abrupt surges of water known as storm surges are associated with cyclones. They strike the coast nearly at the same time that the centre of the storm crosses the coast. In Bangladesh the maximum value of this storm surge has been reported to be as high as 13m. Most of the damage during a cyclone is done by the storm surges, which sometimes wash over entire offshore islands and large areas on the coast.
The most destructive element of a cyclone is its accompanying surge. There is little that can withstand a great mass of onrushing water often as high as 6m. In Bangladesh, cyclones occur in April-May and also in September-December. On an average, five severe cyclonic storms hit Bangladesh every year and the accompanying surge can reach as far as 200 km inland. Surge-heights increase with the increase of wind speed. Astronomical tides in combination with cyclonic surges lead to higher water levels and hence severe flooding.
Storm surges accompanying cyclones hitting Bangladesh have been noted to be 3m to 9m high. The 1970 cyclone (12-13 November) with a cyclonic surge of 6m to 10m and a wind speed of 222 km/h occurred during high tide causing an appalling natural disaster that claimed 0.5 million human lives. The cyclone of 29 April 1991 hit Chittagong, Cox's Bazar, Barisal, Noakhali, Patuakhali, Barguna and Khulna along with a tidal bore (6.1m to 7.6m), killing 140,000 people.
Cyclones in the Bay of Bengal Because of the funnel shaped coast of the Bay of Bengal, Bangladesh very often becomes the landing ground of cyclones formed in the Bay of Bengal. The Bay cyclones also move towards the eastern coast of India, towards Myanmar and occasionally into Sri Lanka. But they cause the maximum damage when they come into Bangladesh, west bengal and Orissa of India. This is because of the low flat terrain, high density of population and poorly built houses. Most of the damage occur in the coastal regions of Khulna, Patuakhali, Barisal, Noakhali and Chittagong and the offshore islands of Bhola, Hatiya, Sandwip, Manpura, Kutubdia, Maheshkhali, Nijhum Dwip, Urir Char and other newly formed islands.
From 1981 to 1985, 174 severe cyclones (with wind speeds of more than 54 km/hr) formed in the Bay of Bengal. The month-wise occurrence is as follows: 1 in January, 1 in February, 1 in March, 9 in April, 32 in May, 6 in June, 8 in July, 4 in August, 14 in September, 31 in October, 47 in November and 20 in December. It is apparent from the above figures that severe cyclones occur mostly during pre-monsoon (April-May) and post-monsoon (September-December) periods and they are the ones which cause the most destruction.
Chronology of major cyclonic storms
1584 Bakerganj (presently Barisal) and Patuakhali; hurricane with thunder and lightening continued for five hours; the houses and boats were swallowed up, leaving only Hindu temples on a height; about 2,000,000 living creatures perished.
1585 Mouth of the Meghna estuary; severe storm wave swept up the eastern side of Bakerganj; number of living creatures perished, standing crops destroyed.
1797 (November) Chittagong; severe cyclonic storm; every hut levelled to the ground and 2 vessels sunk in chittagong port.
1822 (May) Barisal, Hatiya Island and Noakhali district; severe cyclonic storm with storm wave; Collectorate records swept away, 40,000 people killed and 100,000 cattle lost.
1831 (October) Barisal; storm-wave; many lives lost and cattle destroyed (exact figures not available).
1872 (October) Cox's Bazar; cyclonic storm; exact figures of the loss of lives and cattle are not available.
1876 (31 October) Meghna estuary and coasts of Chittagong, Barisal, Noakhali; most severe storm-surge of about 12.2m (40 ft) height; about 200,000 people died during the storm, but perhaps more people died from the after-effects of the storm, such as epidemic and famine, and enormous properties destroyed by tidal bore. Considering the population at that time, a death figure of 200,000 was indeed too heavy.
1897 (24 October) Chittagong; hurricane reached maximum intensity with series of storm-waves; Kutubdia Island and coastal villages were swept over, 14,000 people killed and 18,000 died in epidemics (cholera) that followed.
1898 (May) Teknaf; cyclonic storm-waves; exact figures of damage not available.
1904 (November) Sonadia; cyclonic storm; 143 killed and fishing fleet wrecked.
1909 (16 October) Khulna; cyclonic storm-waves; killed 698 people and 70,654 cattle.
1913 (October) Muktagachha upazila (Mymensingh); cyclonic storm; demolished many villages killing about 500 persons.
1917 (24 September) Khulna; hurricane; 432 persons killed and 28,029 cattle lost.
1941 (May) Eastern Meghna estuary; cyclonic storm with storm-wave; exact figures of the loss of lives and cattle aer not available.
1948 (17-19 May) Between Chittagong and Noakhali; cyclonic storm; about 1,200 persons killed and 20,000 cattle lost.
1958 (16-19 May) East and west Meghna estuary, east of Barisal, Noakhali; cyclonic storm along with surge; 870 persons killed, 14,500 cattle lost and standing crops destroyed.
1958 (21-24 October) Chittagong coast; cyclonic storm; about 100,000 families lost their homes and government had to provide house-building loans.
1960 (9-10 October) Eastern Meghna estuary (Noakhali, Bakerganj, Faridpur and Patuakhali); severe cyclonic storm, maximum wind speed 201 km/hr, maximum storm wave 3.05m; considerable damage to Char Jabbar, Char Amina, Char Bhatia, Ramgati, Hatiya and Noakhali; 3,000 lives lost, 62,725 houses damaged, crops on 94,000 acres of land were fully damaged and thousands of cattle perished.
1960 (30-31 October) Chittagong, Noakhali, Bakerganj, Faridpur, Patuakhali and eastern Meghna estuary; severe cyclonic storm, maximum wind speed 210 km/hr, surge height 4.5-6.1m; about 10,000 persons killed, 27,793 cattle lost and 568,161 houses destroyed (especially 70% of houses in Hatiya blown off), two large ocean liners washed ashore, 5-7 vessels capsized in Karnafuli river.
1961 (9 May) Bagerhat and Khulna; severe cyclonic storm with a wind speed of 161 km/hr, surge 2.44-3.05m; rail track between Noakhali and Harinarayanpur damaged, heavy loss of life in Char Alexander, 11,468 people killed and about 25,000 cattlehead destroyed.
1962 (26-30 October) Feni; severe cyclonic storm with a wind speed of 161 km/hr, surge 2.5-3.0m; heavy loss of life; about 1,000 people died and many domestic cattle perished.
1963 (28-29 May) Chittagong, Noakhali, Cox's Bazar and the offshore islands of Sandwip, Kutubdia, Hatiya and Maheshkhali were badly affected; severe cyclonic storm with storm-wave rising 4.3-5.2m in Chittagong, maximum wind speed 203 km/hr and at Cox's Bazar 164 km/hr; more than 11,520 people killed, 32,617 cattle lost, 376,332 houses, 4,787 boats and standing crops destroyed.
1965 (11-12 May) Barisal and Bakerganj; most severe cyclonic storm, maximum speed 162 km/hr with storm-wave rising 3.7m; total loss of life 19,279; in Barisal alone 16,456 people killed.
1965 (14-15 December) Cox's Bazar along with adjacent coastal area and Patuakhali; severe cyclonic storm with storm-wave rising 4.7-6.1m; maximum speed 210 km/hr in Cox's Bazar, hoisted danger signal 10 at Cox's Bazar and along the coast of Sonadia, Rangadia and Hamidia islands, and Patuakhali; 40,000 salt beds in Cox's Bazar inundated and 873 people killed.
1966 (1 October) Sandwip, Bakerganj, Khulna, Chittagong, Noakhali and Comilla; severe cyclonic storm with storm-waves of 4.7-9.1m, maximum wind speed 146 km/hr; affected 1.5 million people, loss of human life and livestock were 850 and 65,000 respectively in Noakhali and Bakerganj.
1969 (14 April) Demra (Dhaka district); tornado locally known as Kalbaishakhi with wind speed of 643 km/hr; 922 people killed and 16,511 injured; estimated loss Tk 40 to 50 million.
1970 (12-13 November) The most deadly and devastating cyclonic storm that caused the highest casualty in the history of Bangladesh. Chittagong was battered by hurricane winds. It also hit Barguna, Khepupara, Patuakhali, north of Char Burhanuddin, Char Tazumuddin and south of Maijdi, Haringhata and caused heavy loss of lives and damage to crops and property. Officially the death figure was put at 500,000 but it could be more. A total of 38,000 marine and 77,000 inland fishermen were affected by the cyclone. It was estimated that some 46,000 inland fishermen operating in the cyclone affected region lost their lives. More than 20,000 fishing boats were destroyed; the damage to property and crops was colossal. Over one million cattlehead were reported lost. More than 400,000 houses and 3,500 educational institutions were damaged. The maximum recorded wind speed of the 1970 cyclone was about 222 km/hr and the maximum storm surge height was about 10.6m and the cyclone occurred during high-tide.
1971 (5-6 November) Chittagong coast; severe cyclonic storm; exact figures of the loss of lives and cattle are not available
1971 (28-30 November) Sundarban coast; cyclonic storm with a wind speed of 97-113 km/hr and storm surge of less than 1m; Khulna district experienced stormy weather and low lying areas of Khulna town inundated.
1973 (6-9 December) Sundarban coast; severe cyclonic storm accompanied by storm surge; low-lying coastal areas of Patuakhali and adjoining offshore islands inundated.
1974 (13-15 August) Khulna; cyclonic storm with a wind speed of 80.5 km/hr; about 600 lives lost and number of cattlehead destroyed.
1974 (24-28 November) Coastal belt from Cox's Bazar to Chittagong and offshore islands; severe cyclonic storm with a wind speed of 161 km/hr and storm surge of 2.8-5.2 m; 200 people killed, 1000 cattle lost and 2,300 houses perished.
1975 (9-12 May) Bhola, Cox's Bazar and Khulna; severe cyclonic storm with a wind speed of 96.5 to 112.6 km/hr; 5 persons killed and a number of fishermen missing.
1977 (9-12 May) Khulna, Noakhali, Patuakhali, Barisal, Chittagong and offshore islands; cyclonic storm with a wind speed of 112.63 km/hr; exact figures of the loss of lives and cattle are not available.
1983 (14-15 October) Offshore islands and chars of Chittagong and Noakhali; severe cyclonic storm with a wind speed of 122 km/hr; 43 persons killed, 6 fishing boats and a trawler lost, more than 150 fishermen and 100 fishing boats missing and 20% aman crops destroyed.
1983 (5-9 November) Chittagong, Cox's Bazar coast near Kutubdia and the low lying areas of St Martin's Island, Teknaf, Ukhia, Moipong, Sonadia, Barisal, Patuakhali and Noakhali; severe cyclonic storm (hurricane) with a wind speed of 136 km/hr and a storm surge of 1.52m height; 300 fishermen with 50 boats missing and 2,000 houses destroyed.
1985 (24-25 May) Chittagong, Cox's Bazar, Noakhali and their offshore islands (Sandwip, Hatiya, and Urirchar); severe cyclonic storm, wind speed Chittagong 154 km/hr, Sandwip 140 km/hr, Cox's Bazar 100 km/hr and storm surge of 3.0-4.6m; about 11,069 persons killed, 94,379 houses damaged, livestock lost 135,033 and road damaged 74 km, embankments damaged.
1986 (8-9 November) Offshore island and chars of Chittagong, Barisal, Patuakhali and Noakhali; cyclonic storm hit 110 km/hr at Chittagong and 90/hr at Khulna; 14 persons killed, damaged 97,200 ha of paddy fields, damage to schools, mosques, warehouses, hospitals, houses and buildings at Amtali upazila in Barguna.
1988 (24-30 November) Jessore, Kushtia, Faridpur, offshore islands and chars of Barisal and Khulna; severe cyclonic storm with core wind speed 162 km/hr, storm surge of 4.5m at Mongla point; killed 5,708 persons and lot of wild animals - deer 15,000, Royal Bengal Tiger 9, cattle 65,000 and crops damaged worth about Tk 9.41 billion.
1991 (29 April) The Great Cyclone of 1991, crossed the Bangladesh coast during the night. It originated in the Pacific about 6,000 km away and took 20 days to reach the coast of Bangladesh. It had a dimension of more than the size of Bangladesh. The central overcast cloud had a diameter exceeding 600 km. The maximum wind speed observed at Sandwip was 225 km/hr. The wind speeds recorded at different places were as follows: Chittagong 160 km/hr, Khepupara (Kalapara) 180 km/hr, Kutubdia 180 km/hr, Cox's Bazar 185 km/hr, and Bhola 178 km/hr. The maximum wind speed estimated from NOAA-11 satellite picture obtained at 13:38 hours on 29 April was about 240 km/hr. The cyclone was detected as a depression (wind speed not exceeding 62 km/hr) on the 23rd April first in the satellite picture taken at SPARRSO from NOAA-11 and GMS-4 satellites. It turned into a cyclonic storm on 25 April. The cyclone in its initial stage moved slightly northwest and then north. From 28 April it started moving in a north-easterly direction and crossed the Bangladesh coast north of Chittagong port during the night of the 29th April. The cyclone started affecting the coastal islands like Nijhum Dwip, Manpura, Bhola and Sandwip from the evening of that day. The maximum storm surge height during this cyclone was estimated to be about 5 to 8m. The loss of life and property was colossal. The loss of property was estimated at about Tk 60 billion. The death toll was estimated at 150,000; cattlehead killed 70,000.
1991 (31 May to 2 June) Offshore islands and chars of Patuakhali, Barisal, Noakhali and Chittagong; cyclonic storm, maximum wind speed 110 km/hr and surge height of 1.9m; people killed, cattlehead perished, boats lost and standing crops destroyed.
1994 (29 April 3 May) Offshore island and chars of Cox's Bazar; severe cyclonic storm with maximum wind speed of 210 km/hr; people killed about 400, cattle lost about 8,000.
1995 (21-25 November) Offshore island and chars of Cox's Bazar; severe cyclonic storm with maximum wind speed of 210 km/hr; about 650 people killed, 17,000 cattlehead perished.
1997 (16-19 May) Offshore islands and chars of Chittagong, Cox's Bazar, Noakhali and Bhola; severe cyclonic storm (hurricane) with a wind speed of 225 km/hr, storm surge of 3.05m (similar strength to that of 1970 cyclone); only 126 people killed because of better disaster management measures taken by the government and the people.
1997 (25-27 September) Offshore islands and chars of Chittagong, Cox's Bazar, Noakhali and Bhola; severe cyclonic storm (hurricane) with a wind speed of 150 km/hr, storm surge of 1.83 to 3.05m.
1998 (16-20 May) Offshore islands and chars of Chittagong, Cox's Bazar and Noakhali; severe cyclonic storm (hurricane) with a wind speed of 150 km/hr, storm surge of 1.83 to 2.44m.
1998 (19-22 November) Offshore islands and chars of Khulna, Barisal and Patuakhali; cyclonic storm with maximum wind speed of 90 km/hr, storm surge of 1.22 to 2.44m.
2007 (15-17 November) Severe cyclonic storm 'Sidr' causes immense damage in southern part of Bangladesh; about 3000 persons killed.
2009 (19-21 April) Cyclone 'Bijli' attacked weakly in Bangladesh and not so severe damages were recorded except some houses and crop fields losses.
2009 (27-29 May) A severe cyclonic storm 'Aila' attacked offshore 15 districts of south-western part of Bangladesh;' about 150 persons killed, 2 lac houses and 3 lac acres of cultivated land and crops losses.
Weather satellites in cyclone warning Bangladesh does not have satellite facilities of its own, but with the help of ground stations, it receives weather pictures from weather satellites launched by advanced countries. An APT (Automatic Picture Transmission) Ground Station for the reception of imagery from weather satellites was established in 1968 in Bangladesh (then East Pakistan). Recently SPARRSO has established advanced receiving and analysing equipment with financial assistance from USAID under NASA's supervision. With the help of this equipment both low and high-resolution data from American NOAA-14 and NOAA-15 and Japanese GMS-5 satellites are received. The GMS satellites transmit data every hour. Data from NOAA satellites are obtained every six hours. An automatic grid, ie latitude, longitude and national boundaries are fitted in the picture with the help of the present equipment. Because of this equipment, no cyclone in the Bay of Bengal can escape notice.
Prevention The energy in a severe cyclone is equivalent to that of several thousand atom bombs of megaton strength and hence it is difficult even at this advanced stage of technology to try to modify a tropical cyclone. The United States has conducted experiments in the Atlantic by spraying silver iodide in the region of the maximum wind speed to minimise the wind speed. These experiments, though very promising, have remained inconclusive. Moreover, there is a chance that these cyclones could change their track and move towards another direction. Other methods which have been suggested for preventing the formation or reducing the severity of tropical cyclones is to cover the probable area of sea surface with a thin layer of oil or some chemical substance for reducing evaporation. However, the pollution effect of this gigantic effort needs to be considered before this experiment could be carried out.
Protection Cyclone is a natural phenomenon like an earthquake or a volcanic eruption. Countries like Bangladesh have to learn to live with it. By strengthening the cyclone warning system and adopting protective and relief measures, the damage could be minimised. Bangladesh today has a comprehensive Cyclone Preparedness Programme (CPP) jointly operated by the Bangladesh Red Crescent Society and the Ministry of Disaster Management and Relief. It has a membership of about 32,000 devoted volunteers spread over 2,043 wards of 195 unions of the coastal belt of Bangladesh. In each ward the trained volunteers are ready to do the needful in the event of a cyclone. Each ward is provided with a transistor radio, a megaphone-cum-siren, a signal torchlight and first aid kit. Almost every upazila is provided with a wireless set, which keeps direct communication with Dhaka.
The entire government machinery including the army, the navy, the air force and the relevant ministries and organisations are required to discharge their duties in the event of a cyclone. There is a standing order pertaining to cyclones, which lay down actions by all during the various stages of the disaster.
Cyclone warning and preparedness measures have improved in Bangladesh in recent years. This has been amply demonstrated during the catastrophic cyclone that struck Bangladesh in 1997. Some 2,500 cyclone shelters have been built and a coastal greenbelt project for afforestation of the coastal areas is also in progress. The improved cyclone warning system and mobilisation of people before the impending cyclones have been very effective in minimising the death toll. [Masud Hasan Chowdhury]
Bibliography AM Chowdhury, 'Rose Petals for Tropical Cyclones', Nuclear Science and Applications (118), 1978; AM Chowdhury et al, 'Steering Wind Effects on Cyclone Tracks in the Bay of Bengal', The Dhaka University Journal of Science 43 (1), January 1995; BBS, 1998 Statistical Yearbook of Bangladesh (19th edition), Bangladesh Bureau of Statistics, Government of the People's Republic of Bangladesh, 1999; K Nizamuddin (ed), Disaster in Bangladesh: Selected Readings, Disaster Research Training and Management Centre, University of Dhaka, 2001.