Cyclone Data
Bangladesh suffers huge from tropical cyclones every decade & its impact is devastating. These tropical
cyclones get their energy from intense evaporation over warm water, from opposing temperatures between cold
& warmer air masses. Tropical cyclones affecting Bangladesh have killed about 1.54 million people in Bengal.
(Hossain, 1994). On average, five cyclones originate in the Bay of Bengal every year during the monsoon
period. The rate of date in Bangladesh from 1484 to 2020 from cyclone is about more than a million. The most
devastated cyclones happened in Bangladesh were Bhola (1970), Gorky (1991) and Sidr (2007). (Tahmina
Hadi, 2021). In Bangladesh, cyclones have two peaks in a year during April & May (pre monsoon) & between
October & November (post monsoon). Information on storm surge is very scarce in Bangladesh. But some
literature provides a range of 1.5 to 9.0 meter high storm surges during various serious cyclones. (Haider,
Rahman, Haque, & Studies, 1991). However, a SMRC report shows the height for 1876 cyclone was 13.6 meter
at Bakerganj & the surge height for 1970 cyclone was 10 meter. (Karmakar, 1998). The number of fatalities
from the cyclones during the 1970–2007 period decreased at the rate of 2.5% per year. Cyclone Bhola (12
November 1970) severely affected the coastal region of Bangladesh. It claimed 500,000 lives and caused a
damage worth USD 450 million, making it the deadliest natural disaster in Bangladesh and human history. Exact
number is 864 USD million. The speed of the cyclone Bhola was 224 (km/h). About 912,000 houses was fully
and partial damaged & category was 3 & surge height was 3 to 10 meter. Cyclone Gorky (29 April 1991) killed
138,882 people and caused a damage estimated at USD 1.8 billion. Around 4.5 million people were directly or
indirectly affected by Gorky. 1 million houses was destroyed by Gorky cyclone. Category was 4 & tidal surge
height was 3.7 to 6.7 meter. Wind speed of the Gorky cyclone was 225 (km/h). Location of both cyclone Gorky
& Bhola was in Chittagong (Tahmina Hadi, 2021). “Cyclone Sidr (Category 4, 15 November 2007) made a
landfall across the southwestern region of Bangladesh. It claimed 3363 lives, significantly fewer than in 1970
and 1991 cyclones”. (Department, 2007). However, more than 27 million people were affected in 30 districts of
Bangladesh. More than 500,000 houses and an additional 900,000 houses were destroyed and highly damage.
It’s landfall location was in Khulna-Barisal Coast near Baleshwar River. Maximum wind speed was 223 (km/h).
Category was 4 & tidal surge height was 4.6 to 6 meter. 565,000 houses was totally destroyed over 950,000
significantly destroyed in Sider. Cyclone Aila , (25 May 2009) affected 11 southwestern coastal districts,
claimed 190 lives, injured more than 7000 people and affected about 4.8 million people. Landfall area of the
cyclone Aila was in West Bengal-Khulna Coast near Sagar Island. Wind speed was 70 to 90 (km/h) & tidal
surge height was 3 meter. Category was 1 & damage of property was 1000 million USD. Cyclone Amphan
(Category 1, 20 May 2020) made a landfall in the southwestern Bangladesh, affecting 2.6 million people,
destroying 55,767 houses, damaging 76 km of embankment and 440 km of road across more than 19 districts.
The death toll was 22. Maximum speed was 160 (km/h) & tidal surge height was 3.4 to 6 meter. About 375
million USD property was destroyed. (Tahmina Hadi, 2021). A study aims to integrate geospatial technologies
with major disasters and compares them. This study considered southwestern and central parts of the coastal
region which covers 10 districts for the analysis. The cell size is fixed to 10 m for pre- and post-disaster images
for Cyclone “Fani,” but it varies with Cyclone “Ayla” where the cell size is kept 30 m for pre- and post-disaster
images. The output of Change vector analysis represents changes in intensity in a particular area. The magnitude
of change is represented by color intensity. The intense color represents the high intensity of change, and the
much lighter color represents the low intensity of change. In the 1988 cyclone, it shows massive intensity toward
Bhola district and arrows directing toward Barishal, Lakhimpur and Bhola. In 1991, greater intensity can be seen
in the Satkhira district. In 2007 it shows medium intensified areas all over the study area and some deeply
intense regions like Barishal, Satkhira, Khulna. In 2009 it shows deeply stricken areas in some parts of Bhola,
Khulna and Barishal. In 2009 there was a mixed and medium severity in Barishal, Bhola, Patuakhali and
Barguna Districts. In land use the results of class change between early and post-disaster are represented
statistically. In 1988 a huge change in the water body and Pasture land was detected. In 1991 it represents a
change in water body and forest and vegetation. In 2009 it shows a change in water bodies and vegetation. In
2019, changes can be seen in water body and forest. Geospatial techniques needed to be integrated with this
evaluation for precise measurements. (Rahaman, 2021). Other study had conducted AHP-based geospatial multicriteria evaluation approach for tropical cyclone risk assessment. The present study was conducted in the eastern
coastal region of Bangladesh, which covers Chittagong and Cox's Bazar coastal districts. The produced
vulnerability and exposure map shows that 40% (3056 km) of the study area was exposed to high to very-high
vulnerability to tropical cyclone impacts. (Hoque)
Bibliography
1. Department, B. M. (2007).
2. Haider, R., Rahman, A. A., Haque, S., & Studies, B. C. (1991). Cyclone '91, an environmental and
perceptional study. Dhaka, Bangladesh : Bangladesh Centre for Advanced Studies, [1991].
3. Hoque, M. A.-A. (n.d.). Tropical cyclone risk assessment using geospatial techniques for the eastern coastal
region of Bangladesh. Science of The Total Environment, 692, 10–22.
https://doi.org/10.1016/J.SCITOTENV.2019.07.132.
4. Hossain, I. &. (1994). Cyclone and Bangladesh: A Historical and Environmental Overview from 1582 to
2020. International Medical Journal (1994). 25. 2595-2614.
5. Karmakar, D. S. (1998). "Vertically-integrated tropospheric moisture, energyand their fluxes over Bangladesh
during landfall of tropical cyclones",Mausam, 49, 2, pp. 187-194.
6. Rahaman, M. E.-U.-Z. (2021). Evaluating the impacts of major cyclonic catastrophes in coastal Bangladesh
using geospatial techniques.
7. Tahmina Hadi, M. S. (2021). Seeking Shelter: The factors that influence refuge since Cyclone Gorky in the
Coastal Area of Bangladesh,.