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IMPACTS OF CYCLONE IN BANGLADESH INTRODUCTION Bangladesh currently ranks as one of the world's foremost disaster-prone country. The situation is aggravated, all the more by its being the most densely populated country in the world. Environmental disasters like tropical cyclones, storm surges, floods, norwesters, tornadoes and droughts ravage the country almost every year. During the last forty years, the country was devastated by forty severe cyclones of varying intensities. One of the severe ones in recent times was that of 29 April 1991, when material damage was to the tune of about 2.4 billion US dollars and human casualty of about 1, 40,000 lives. On a previous occasion of a similar catastrophe in 1970, about half a million lives were lost. The Bangladesh flood of 1988 caused economic loss to the extent of about one billion dollar. The loss due to the current 1998 flood of Bangladesh has exceeded that due to any previous flood and may be around two billion dollars. And flooding in Bangladesh is a perennial problem. Every year Bangladesh is also affected by norwesters and tornadoes causing loss of lives and immense damage to property. Though Bangladesh is affected by floods frequently it is not spared from drought which occurs in Bangladesh occasionally causing extensive damage to crops. Bangladesh also lies in the seismic zone and hence comes under the risk of earthquakes. SUMMARY OF 1991 CYCLONE On April 30, 1991, Cyclone Marian swept across the southeastern coast of Bangladesh, lashing the area with winds up to 210 kilometers per hour and gusts up to 235 per hour. A storm surge of over six meters submerged coastal areas and small offshore islands, causing massive loss of life and destruction. Approximately 13.4 million people lived in the affected areas. As sea waters receded and more bodies were uncovered, the death toll rose to almost 139,000, with an equal number of injured. On Kutubdia, an offshore island with a pre-cyclone population of 110,000 people, more than 20,000 died. An aerial survey of the island by USAID staff revealed that 80 percent to 90 percent of all structures were destroyed and all livestock lost. Entire populations were wiped out on some of the smaller islands. Some of the major devastating cyclones that caused enormous damage and deaths of huge numbers of people and animals are summarized in Table 1. This table shows the name of the cyclones, year of occurrence, date of month of occurrence, category of severity and return period. As can be seen from this table that the all the 1

four major cyclones are of category 3 or 5 indicating the power, severity and extent of the destructive cyclones. It is observed that the return period of the devastating cyclones was 50 years in 1970 or earlier, whereas it was 21 years in 1991. It is evident that the return period of both Orissa and Sidr cyclone is 8 years which indicates that it decreases remarkably especially in the couple of decades. Table 1. Name of major cyclones in Bangladesh, date of their occurrence, category of severity and return period Name of cyclones Year of Date and Category of Return occurrence Month of severity period Occurrence Great Bhola 1970 12 November 3 50 cyclone Tropical cyclone 1991 30 April 5 21 Orissa cyclone 1999 29 October 4 8 Sidr cyclone 2007 15 November 5 8 Source: Hossain, et al. 2008. PHYSICAL FACTS, CYCLONE PATH AND SEVERITY The path of the two recent severe cyclones along with the physical facts of Bangladesh is shown in Fig.2. It should be noted that Bangladesh extends between 21o and 27o North latitude and 88o and 92.5o East longitude. The Bay of Bengal is in the south side of the country. The coastal land of Bangladesh (710 km long) is of recent origin formed out of the process of sedimentation. Most parts of the area are, therefore, low lying which can be subjected to inundation even under ordinary circumstances of tides. A tidal surge accompanied by a cyclone storm makes the situation alarming which is further exacerbated by the triangular shape of the Bay of Bengal (Fig.1). The country has been subjected to frequent natural disasters in many forms, particularly cyclonic storms and tidal surges. From 1970 to 2007, four major cyclone storms and tidal surges have been reported. During the 1991 cyclone, the cyclonic storm was detected as a low pressure area over the Southeast Bay and adjoining Andaman Sea on 23 April. Finally, the cyclone of hurricane intensity crossed the Chittagong coast a little north of Chittagong at 2 am of 30 April, 1991 that killed some 143000 people in Bangladesh. The 2007 cyclone Sidr smashed into the country's southern coastline late on Thursday midnight of November 15 with 250 km/h (155 m/h) winds that whipped up a five meter tidal surge and swept about 20 km inland, a grade 5 hurricanes, the highest level possible, devastated 23 districts in the south western part of

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Bangladesh.

Fig: 1 Direction of major two cyclones in Bangladesh

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TROPICAL CYCLONES The tropics can be regarded as the region of the earth lying between 30oN latitude and 30oS latitude. All the tropical seas of the earth with the exception of the south Atlantic and east south Pacific give birth to deadly atmospheric phenomena known as tropical cyclones. On the average, 80 tropical cyclones are formed every year all over the globe. Bangladesh is a part of humid tropics, with the Himalayas in the north and the funnel shaped coast touching the Bay of Bengal in the south. This peculiar geography of Bangladesh causes not only the life giving monsoons but also catastrophic ravages of cyclones, nor wresters, tornadoes and floods. The Bay of Bengal is an ideal breeding ground for tropical cyclones. A list of the major cyclones affecting Bangladesh is given in Table-2. Table 2: Cyclones affecting Bangladesh since 1960

Date

Max. wind speed in km/hr

Storms surge ht. (In ft.)

Deaths

09 Oct. 1960 30 Oct. 1960 09 May 1961 30 May 1961 28 May 1963 11 April 1964 11 May 1965 31 May 1965 14 Dec. 1965 01 Oct. 1966 11 Oct. 1967 24 Oct. 1967 10 May 1968 17 April 1969 10 Oct. 1969 07 May 1970 23 Oct. 1970 12 Nov. 1970 08 May 1971 30 Sep. 1971 06 Nov. 1971 18 Nov. 1973 09 Dec. 1973 15 Aug. 1974 28 Nov. 1974 21 Oct. 1976 13 May 1977

162 210 146 146 203 162 210 146 223 122 97 162 105 122

10 15-20 8-10 20-29 14-17 12 20-25 15-20 15-30 6-28 5-25 9-15 8-24 10-16 20-30 8-14 8-14 8-18 8-13 5-15 5-22 7-16 8-16 -

3,000 5,149 11,466 11,520 196 19,279 873 850 75 300 00 183 Few 4

10 Dec. 1981 15 Oct. 1983 09 Nov. 1983 03 June 1984 25 May 1985 29 Nov. 1988 29 April 1991 02 June 1991 02 May 1994 19 May 1997 26 Sept. 1997 20 May 1998

97 97 122 89 154 162 140 100 200 225 150 120

06 10-15 5-10 20-25 06 15 10 05

02 11,069 2,000 1,38,000 170 126 70 03

Source: Choudhury, cited in: Bangladesh Unnayan Parishad, 16-18 March, 2002

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Fig 2: Direction of cyclone throughout the different year.

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DETERMINATION OF THE CYCLONE TRACK: The precise forces responsible for the motion of tropical cyclones are not understood clearly and hence determination of the path of the cyclone in advance is one of the most difficult tasks in meteorology. Recently various statistical and numerical dynamical methods have also been introduced for the forecast of cyclone paths. Steering Principle was first applied by H. Mohn in 1870. Until 1950 forecasts of tropical cyclones were made by subjective methods based on synoptic maps and climatologicall behavior. Following are some of the objective methods applied in modern times for cyclone forecasting. Statistical methods relate predicted movement to one or more parameters in an empirical way. Dynamical techniques, on the other hand make use of some forms of the equation of motion to predict numerically the motion of cyclone from an observed initial state of the atmosphere. Hybrid model in which output parameters from a dynamical model are used in a statistical model. SPARRSO has installed a model named TYAN for predicting the track of a cyclone based on climatology of Bay of Bengal Cyclones for the last one hundred years. DAMAGE CAUSED BY CYCLONE Damage was widespread and severe in all sectors. According to Government of Bangladesh (GBD) estimates, 780,000 homes were destroyed, 9,300 schools damaged or destroyed, and 655 health centers damaged or destroyed. Power, water, and communications lines to the affected areas were cut, and train, road, and air service was disrupted. More than 190 kilometers of coastal embankments were destroyed and 940 kilometers damaged. Numerous tubewells were damaged or contaminated. In many areas, surface water was salinized, including ponds used for bathing and cleaning. Almost all industries in the port area of Chittagong suffered heavy damage, and the port itself was left in shambles. The agricultural sector sustained serious disruptions. About 247,000 tons of cereal crops and 35,000 tons of vegetables, tubers, and other crops were lost. Damage to coastal embankments, high salinity in some areas, and a shortage of tools, seeds, and fertilizers made the prospects for the main rice crop (June-October) bleak. About 224,000 head of cattle, 218,000 goats, and 2.4 million head of poultry were estimated to have perished in the cyclone. Surviving livestock were in poor health and lacked adequate feed. Losses in the fisheries sector were just as calamitous, with extensive damage to 31,000 hectares of shrimp farms as well as to fish processing plants, vessels, and stocks. The forestry sector suffered

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considerable losses of fuel wood and timber, and coastal mangrove plantations were damaged, increasing the possibility of serious coastal erosion in the future. These losses were expected to be serious obstacles to the affected population’s ability to return to its prior means of livelihood. Cyclone Marian was one of the worst rapid onset disasters of the late twentieth century. PROTECTION AGAINST CYCLONES A cyclone is a natural phenomenon like an earthquake or a volcanic eruption. We have to learn to live with it. We have to strengthen the cyclone warning system and adopt protective and relief measures to minimize their onslaught. SPARRSO monitors the tropical cyclones on an hourly basis with the help of the remote sensing equipment installed and passes the information to all concerned agencies including Bangladesh Meteorological Dept., Bangladesh Air Force, Honorable Prime Minister’s Office, Ministry of Disaster and Relief and so on. With the help of the facilities at SPARRSO, we can determine the location, the intensity and the future course of motions of the cyclone. As a matter of fact no cyclone in the Bay of Bengal can escape the notice of the remote sensing equipment of SPARRSO. An integrated computerized method of Cyclone warning system needs to be developed. SEA ANGEL RELIEF OPERATION The U.S. joint task force (JTF), attempted to maximize the civilian population's participation in the operation - coordinating all its activities with the Bengali government and various nongovernmental organizations. The coordination facilitated the military withdrawal as the situation transitioned from relief to rehabilitation. The JTF also sought to maximize the impact of the operation’s activities on the devastated civilian population. Civilians were encouraged to trust the military force's ability to provide safe, reliable supplies (such as filtered water). Because of the massive devastation throughout Bangladesh, the operation minimized the military footprint and the burden placed on civil society by military demands. DISASTER PREPAREDNESS AND MITIGATION  Adequate shelter must be available and accessible, and residents must not delay in

seeking shelter. Some of those who attempted to respond to the warnings in 1991 could not find appropriate shelter. Investigations afterward found that the number of shelters was not adequate for the number of people at risk. Casualties were significantly lower in areas where people had made use 8

of existing cyclone shelters. In the years immediately allowing the cyclone, there were many attempts to improve and increase the number of shelters. Following the 1994 cyclone, 90 percent of surveyed residents felt that there was more shelter space than there had been in 1991. When the May 1994 cyclone struck, a majority of residents in the affected areas sought shelter, with 80% ending up in shelter outside their homes. About 73 percent of residents from Kutubdia, which had been hardest hit by the 1991 cyclone, sought shelter in a form cyclone shelter.  Coastal embankments, though not without costs, can help protect communities

exposed to flooding. Coastal embankments reduce saline flooding from high lunar tides and storm surges. However, in the case of cyclones, there must be cyclone shelters to provide protection from the high winds and rain. The costs of such embankments are high, as well as highly variable, depending on the slope of the accreted land to be embanked. Great care needs to be taken to ensure that adequate drainage for rainfall runoff is provided and that the embankment location takes into consideration the location of saline water shrimp activities. Embankments need to be designed, constructed, and managed in a multi-purpose way in order to maximize their benefits as places of residence, economic production (from forestry), and transport. One major negative impact is the effect on the movement of migratory fish species. In addition, in cases where settled land has to be acquired for construction purposes, significant conflicts can arise. Careful planning is needed to reduce disruptions to navigation. Embankments often give a false sense of security to some people who wrongly imagine they can take refuge on them  Afforestation in coastal areas and sustainable forest management can help mitigate the effects of cyclones The GBD implemented coastal mangrove planting projects, and the impacts of forestry planting in the coastal areas were nearly all found to be positive. Planting coastal areas with appropriate mangrove species for cyclone protection assists in land stabilization and dissipation of wave energy. Maintaining productive use of the land is also important. Such a policy would need to be managed in a sustainable way, including thinning and cutting the mangroves at suitable times and carrying out forest planting and management activities with the full participation of local people.

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CONCLUSION National Economy can be adversely affected by the occurrence of natural disasters and adequate measures should be taken well in advance to deal with related problems. It is heartening to note that the Government and the various concerns agencies are taking part side by side with the people to ameliorate the sufferings of the people struck by natural disasters. But adequate facilities should be provided to all those participating in the disaster mitigation activities (e.g. Sea Angels of US Army Operation during 1991Cyclone). Above all, economic condition of the country needs to be strengthened so that there are enough resources to face the disasters. We should aim to achieve something like 10% growth rate annually.

BIBLIOGRAPHY A.M. Choudhury : Ravages of Cyclones Published in the Journal 'Bangladesh' Vol. 1, No. 1. Canada, 1974. A.M. Choudhury , Rose Petals for Tropical Cyclone Nucl, Sc. and Appl. Vol 11 B , p 1-7, 1978. A. M. Choudhury : Movemnet of a Tropical Cyclone in the presence of Inclined plane Boundaries and an Azimuthal wind, Journal Bangladesh Math. Soc. Vol. 2, No. 1, pp 2730, 1982. A.M. Choudhury: Abount Cyclones, Space Education, London, 1983. A.M. Choudhury : Bangladesh Floods, Cyclones & the ENSO - presented at the International Monsoon Conference held at Trieste, Italy May, 1994. Proceedings’ published by WMO, Geneva, July 1994. Dr. A. M. Choudhury. In: presented at the dhaka meet on sustainable development in bangladesh: achievements, opportunities and challenges at rio+10organised by bangladesh unnayan parishad, 16-18 march, 2002 EU (European Community). 1998. Cyclone Shelter Preparatory Study (CPSP), Stage I, Feasibility Study, Draft Final Report, Vol. 3. Karim, Nehal (no date) Options for Cyclone Protection: [The] Bangladesh Context. Dhaka: University of Dhaka, Department of Sociology. M. Alam Miah: Flood Monitoring and Forecasting in Bangladesh : Presented at the Seminar on Application of Remote Sensing to Flood Plain Mapping and Flood Monitoring, SPARRSO, Dhaka, December, 1989. 10

M.Z. Hossain, M.T. Islam, T. Sakai and M. Ishida “Impact of Tropical Cyclones on Rural Infrastructures in Bangladesh”. Agricultural Engineering International: the CIGR Ejournal. Invited Overview No. 2, Vol. X. April, 2008. Paul, A., and Rahman, M. 2006. Cyclone Mitigation Perspectives in the Islands of Bangladesh: A Case of Sandwip and Hatia Islands, Coastal Management, 34, Issue 2 April, pp.199215. V.F. Divorak, Tropical Cyclone Intensety Analysis and Forecasting from Satellite Imagery Monthly Weather Review. Vol. 103, p 420, 1975

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