Risk Returns

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] 74

Cyclone hazard and unpredictability:

preparing coastal communities

Yugraj Singh Yadava, Director, Bay of Bengal Programme Inter-Governmental Organisation

he Bay of Bengal (BoB) forms the north-eastern part of

the Indian Ocean. Resembling a triangle in shape, the Bay

is bordered by Bangladesh, India, Indonesia, Malaysia,

Maldives, Myanmar, Sri Lanka and Thailand. It is also the

largest bay in the world by area.

A number of large rivers and their tributaries flow into the BoB,

which is situated in the monsoon belt and receives high rainfall. It

is a hot spot of biological diversity thanks to its coral reefs, estuar-

ies, coastal wetlands and mangroves. More than a quarter of the

world’s population resides in the countries around the bay, many

of them living below the international poverty line of US$1 per day

and dependent on coastal resources for food and livelihood security.

Cyclones in the Bay of Bengal

The BoB is also periodically in the news for the destructive cyclones

storms that occur from time to time. Of the 30 deadliest cyclones in

world history from 1584 to 2008, as many as 22 have occurred here.

Three recent cyclones, Sidr (2007), Nargis (2008) and Aila (2009),

have caused great loss of life and property in Bangladesh, Myanmar

and India respectively.

With a long coastline of over 8,000 kilometres, the Indian subcon-

tinent is exposed to nearly 10 per cent of the world’s tropical

cyclones. Most of these have their genesis over the BoB and strike

the east coast of India. On average, five to six tropical cyclones form

every year, of which two or three could be severe. About four times

as many cyclones occur in the BoB as in the Arabian Sea.

Bangladesh, due to its unique geographic location, frequently

suffers from devastating tropical cyclones. The funnel-shaped

northern portion of the BoB causes tidal bores when cyclones

make landfall, affecting thousands of people living in the coastal

areas. One of the most devastating natural disasters

in recorded history was the 1970 Bhola cyclone in

Bangladesh (then East Pakistan) that alone claimed

more than 500,000 lives. The maximum recorded wind

speed of this cyclone was about 222 kilometres per hour

and the maximum storm surge height was about 10.6

metres. The cyclone occurred during high tide, causing

enormous damage. Table 1 provides a summary of loss

of life and damage to property from cyclones in the BoB

during the period 1900–2010.

Cyclone warning systems in the region

Ocean Observation Systems (OOS) have become vital

for countries bordering the BoB. In 1996, the Indian

National Institute of Ocean Technology (NIOT) estab-

lished the National Data Buoy Programme with the

objective of operating, maintaining and developing

moored buoy observational networks and related tele-

communication facilities in the Indian seas. These data

buoys are offshore floating platforms, fitted with mete-

orological and oceanographic sensors and moored at

specific locations to observe met-ocean data at regular

intervals. The buoys are powered by lithium batter-

ies and are equipped with Global Positioning Systems

(GPS) to provide their locations. The observed data is

then transmitted through satellite along with the loca-

tion reference, in synoptic hours, to the state-of-the-art

shore station facility at NIOT, Chennai. The OOS team

at NIOT has also developed, tested and established a

Tsunami Buoy System, using bottom pressure recorders

in the Indian seas. The new venture has expanded the

2018

Country

Bangladesh

India

Maldives

Myanmar

Sri Lanka

Tropical cyclones (nos)

Killed

626 843

159 130

144 663

1 160

Total affected

73 556 523

87 392 126

23 849

3 935 844

2 060 000

Estimated damage (US$ Million)

4 765.98

8 600.90

30.00

4 079.39

137.30

Table 1: Summary of casualties in the countries around the BoB due to tropical cyclones, 1900 – 2010

Source: EM-DAT, OFDA/CRED International Disaster Database. Université Catholique de Louvain, Brussels, Belgium