Changing Behavior of Cyclone in Bangladesh and its Risk Assessment for Adaptation

Tropical cyclone (TC) is one of the most crucial topics not only for the natural loss but also for physical and economical loss of any country. The Bay of Bengal (BoB) generates number of tropical cyclones in each year. Bangladesh also experiences a number of cyclones. The surface temperature of the sea and air temperature is observed from NOAA high resolution satellite image. The Sea Surface Temperature (SST) of about 27°C and its higher is one of the prerequisite conditions for formation of a TC. But SST has increased by 1.2°C since last 40 years. It can be settled that both the Air Temperature and SST are increasing over the years. This rise in temperature of the BoB contributes to the occurrence of TC. Among the whole coastal zone of Bangladesh, the Chittagong- Cox’s Bazar coast and Barisal-Patuakhali coast are more vulnerable than the other parts. About 35 million people of Bangladesh are living in the TC exposed area. Most of the TC are associated with storm surges and heavy rainfall, which add up to the damages and complications in the risky area in addition to high winds. It also includes flash flood, salt water intrusion, and loss of lands. In case of vulnerability and risk, it is noticed that Bangladesh is hit by Severe TC (Category-5) at least one in every 10 years, where the wind speed crosses 220 Km/hr. The huge amount of rainfall and storm surge result in floods, which in- crease the severity of this hazard. By this time Government takes steps to reduce the damages of the coastal area. Also, the analysis of behavior of the track and damage of Severe TC indicates that the whole coastal zone stays at risk at different times of the year. With proper analysis and measures, the damages caused by TC can be reduced. The management system of TC risk is not sufficient. The study shows that the TC has significant impact of high winds, rainfall and storm surge. Accordingly, it has the impact on all relevant objects on the society in addition to human loss and damage. Though it has the main influence on the coastal areas but rainfall associated with TC has significant impact on all over Bangladesh. The impacts are dependent on the behavior, landfall time and landfall area. The impact has been divided into three classes- low, medium and high. The classified impacts are varying from TC to TC, but high impact is observed more times over southwestern part of Bangladesh. It also influences the vegetation of the coastal part. Proper measurements should be taken to reduce risk of vulnerable areas of TC in Banglades