Lecture-05:

Disasters of Bangladesh: Cyclone and

Storm Surges

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January 20, 2018

URP 4243: Hazards and Disaster Management

Course Teacher: Md. Esraz-Ul-Zannat Assistant Professor Dept. of URP, KUET

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ACKNOWLEDGEMENT

These slides are aggregations for better understanding of the topic

mentioned in the previous slide . I acknowledge the contribution of

all the authors and photographers from where I tried to accumulate

the info and used for better presentation.

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TOPICS TO BE COVERED BY THIS PRESENTATION Cyclones

Cyclones Synonyms

Cyclone Parameters

Classification of Cyclones

Cyclone Hazard Assessment

Cyclone

Areas Prone to Hurricanes/Cyclones/Typhoons

Tracks of cyclones in Bangladesh

Tracks of major cyclones

Prominent Storm Surge Since 1960

Major Cyclones and Storm Surge

Number of cyclonic storms landed in Bangladesh coast in different decades

Monthly distribution of cyclonic storms landed in Bangladesh coast between

1877 and 1990

Major Effects

Cyclone Categories (SoD, BD)

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Possible Mitigatory Measures

Components of Cyclone Master Plan

Storm Surge Inundation

Recent Experience of Cyclone Shelters

Recent initiatives

Standing Orders on Disaster

Cyclone Warning Signals (SoD, BD, 2010)

Telecommunication During A Cyclone

Involvement of Community and Volunteers for Cyclone Management

Cyclone Preparedness Programme (CPP) Government of Bangladesh and

IFRCS

Cyclone Shelters (Current Situation on number and distribution)

Cyclone Shelters (Current Services/practices)

Concluding Remarks

TOPICS TO BE COVERED BY THIS PRESENTATION

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CYCLONES

Low pressure systems or depressions around which the air circulates in an anti-clockwise direction in the northern hemisphere and clockwise direction in the southern hemisphere.

In cyclones, the speed of wind near the earth’s surface is greater than 33 m/s

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Cyclones are always formed over the sea where the water is warm

Between 5 ° and 30 ° N and S Latitudes

When a cyclone moves across the coastline over to land (landfall), it loses its source of energy and begins to dissipate

An anti-cyclone -- also known as a high pressure area -- is a large atmospheric circulation system with the wind flowing clockwise around it in the Northern Hemisphere, and counter-clockwise in the Southern Hemisphere.

CYCLONES (WITH ANTI-CYCLONES)

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Cyclones/Tropical Cyclones (Indian)

Hurricane (Atlantic)

Typhoon (Pacific)

Kal Boishakhi/ Norwester (Bangladesh and part of India)

CYCLONES SYNONYMS

CYCLONE

Eye

Low pressure

Low winds

20-40 km or more

in diameter

Radius of

Maximum Winds

(RMW)

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Cyclones can be predicted but Tsunamis cannot be predicted

Cyclones can cause rainfall, strong winds and thunder storm whereas tsunamis can cause abnormal rise of water

Cyclone is developed with the help of wind and tsunami is developed with the help of an earthquake

A wave caused by an earthquake is a tsunami and a violent tropical storm is a cyclone

CYCLONE AND TSUNAMI

CYCLONE DEPRESSION IN THE BAY OF BENGAL

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CYCLONES

On an average, 80 cyclones are formed each year

Average duration is 9 days

Cyclones may travel up to 10,000 km at a speed (track

speed) of 10- 250 km/h

Cyclones are like humans, they have individual

personalities

Storm surges

Up to 7.5 meters height

Moving up to 50 km inland

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CYCLONE PARAMETERS

Winds

Destructive power increases with the square of its speed

Wind damage is usually higher on the right of the track in the

northern hemisphere

Rainfall

Storm surge

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CLASSIFICATION OF CYCLONES

According to BMD (Bangladesh Meteorological Department)

Depression 28-31 mph

Deep depression 32-38 mph

Cyclonic storm 39-54 mph

Severe cyclonic storm 55-73 mph

Severe cyclonic storm of hurricane

intensity

> 74 mph

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CYCLONE HAZARD ASSESSMENT

Maximum Wind speed analysis

Similar to flood depth frequency analysis

Point of landfall

Probability of cyclone making landfall at different sections

of the coastline

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CYCLONE BASINS

AREAS PRONE TO HURRICANES/CYCLONES/TYPHOONS

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TRACKS OF CYCLONES IN BANGLADESH

TRACKS OF CYCLONES IN BANGLADESH

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TRACKS OF MAJOR CYCLONES

Color coding of storm strength based upon Saffir-Simpson Hurricane Scale

TD TS 1 2 3 4 5

19 tropical depressions (TD) and tropical storms (TS)

CYCLONE HUDHUD, OCTOBER 7-14, 2014

109 killed; loss USD 11 billion 20

PROMINENT STORM SURGE SINCE 1960

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MAJOR CYCLONES AND STORM SURGE

12 November, 1970 (Bhola Cyclone)

Maximum wind speed 250 km/hr

Surge Height 7m

≈ 500,000 people killed

25 May, 1985 (Urir Char)

≈ 11,000 people killed

29 April, 1991

≈ 138,000 people killed

15 November, 2007 Cyclone Sidr

≈ 4,000 people killed

27 May, 2009 Cyclone Aila

≈ 400 people killed

~ Reduction in the number of people killed

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NUMBER OF CYCLONIC STORMS LANDED IN BANGLADESH

COAST IN DIFFERENT DECADES

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MONTHLY DISTRIBUTION OF CYCLONIC STORMS LANDED

IN BANGLADESH COAST BETWEEN 1877 AND 1990

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MAJOR EFFECTS

Loss of human lives

500,000 in 1970; 138,000 in 1991

Loss of livestock

Infrastructure damage

Total disruption of socio-economic activities

Environmental degradation

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About 7% of the country

with a population of 10

million live in Risk Zone

In 1970, 300,000 people lost their lives

Cyclone

1970 : 500,000 people lost their lives

1991 : 138,000 human deaths,

property losses US $ 1.78 billion.

CYCLONE AND STORM SURGE

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CYCLONE CATEGORIES (SOD, BD)

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CYCLONE CATEGORIES

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http://www.nhc.noaa.gov/aboutsshws.php

POSSIBLE MITIGATORY MEASURES

Evacuation

Embankments/Sea Walls

Afforestation

Strong Houses

Community Shelters

Human population

Livestock

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EMBANKMENTS/SEA WALLS

Many of the areas are protected by earthen embankments (levees)

Not designed to resist storm surges

Provide a false sense of security

In 1991, thousands of people took shelter on or behind embankments and were killed when the embankments failed

Embankments capable of resisting storm surge have been built in Chittagong EPZ; too expensive and justified only when valuable assets have to be protected

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EVACUATION INLAND

Possible only in some locations in south-east (Chittagong

and Cox’s Bazar)

Not possible in offshore islands where the whole island is

inundated

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STRONG HOUSES

Experience of 1991 : Properly built buildings (brick masonry or RC)

can withstand forces due to storm surge

Too expensive for most of the population

Solution : Community Shelters

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COMPONENTS OF CYCLONE MASTER PLAN

Shelters

Planning

Design

Construction

Maintenance

Management

Communication

Warning System

Lighting Energy

CPP Volunteers

Community Development

Telecommunications

Public Awareness

Private Housing

Afforestation

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STORM SURGE INUNDATION

Risk Zone

any place which is likely to be inundated

High Risk Area

strip of land within the Risk Zone extending from the coast line

up to a limit where the depth of inundation may reach 1 meter

based on : records of past storm surges + results from

mathematical model + field survey

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RISK ZONE AND HIGH RISK AREA

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HIGH RISK AREA

Population in HRA in 2005 : 7 million (5% of total

population of Bangladesh)

Area of HRA : 9,200 sq. km. (6.4% of total)

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SURGE HEIGHT AT THE SEA COAST

Region Surge height at the Sea coast along

with 90% confidence limits (m)

20-year return

period

50 year return

period

100 year

return

period

Teknaf to Cox’s Bazar 2.7±0.7 3.7±0.8 4.5±1.3

Chakaoria to Anwara and

Maheshkhali –Kutubdia Islands

4.3±0.9 5.8±1.3 7.0±1.6

Chittagong to Noakhali 4.8±1.0 6.5±1.4 7.8±1.8

Sandip, Hatiya and all islands

in the region

4.8±1.0 6.5±1.4 7.8±1.8

Bhola to Barguna 3.8±0.8 5.1±1.1 6.2±1.5

Sarankhola to Shymnagar 3.1±0.7 4.3±1.0 5.2±1.2

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RECENT EXPERIENCE OF CYCLONE SHELTERS

Multistoried buildings on stilts

With ground floor left open

Raised earthen platforms (killas)

Buildings on killas

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NORMAL TIME USE

Primary/Secondary Schools

Vocational Training Centres

Community Centres

Family Welfare Centres/Health Clinics

Offices

Boat Passenger Terminals

Telecommunication Centres

Maximum walking distance : 1.5 km (based on consultation with affected people)

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PLAN OF SHELTER ON KILLA

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Shelter (built with IDA assistance in 1974) unusable due to lack of maintenance 41

Multipurpose Cyclone and Storm Surge Shelter

(Red Crescent Society) 42

RECENT INITIATIVES

New cyclone shelters being built to add to around 2,500

shelters now usable; about 50% of the requirement

Fael Khair Programme : Anonymous donor from Saudi

Arabia donates US$130 million

US$110 million for construction of school-cum-cyclone shelters

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SHELTER ON STILTS FAEL KHAIR PROGRAMME

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JAPANESE FUNDED MULTIPURPOSE CYCLONE

SHELTERS PRIMARY SCHOOLS

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STANDING ORDERS ON DISASTER

Ministry of Food and Disaster Management issued the

revised “Standing Orders on Disaster” in 2010

The Standing Orders are guidelines to different

functionaries at the National, Divisional, District, Upazila

and Union level government and non-government

agencies for actions to be taken at different stages of

disaster

The Standing Orders clearly spell out what is to be done,

when and by whom at different stages of disaster.

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CYCLONE WARNING SIGNALS (SOD, BD, 2010)

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CYCLONE WARNING SIGNALS (SOD, BD, 2010)

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CYCLONE WARNING SIGNALS (SOD, BD, 2010)

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CYCLONE WARNING SIGNALS (SOD, BD, 2010)

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TELECOMMUNICATION DURING A CYCLONE

An extensive network of radio

communications facilities in

the coastal areas linked to

Dhaka which consists of a

combination of HF and VHF

radios covering most of the

high risk cyclone areas.

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VILLAGE

UNIT COMMITTEE

First Aid Group Rescue Group Shelter Group Warning Group Relief Group

Warning

Volunteer (L)

Addl. Warning

Volunteer Shelter Volunteer

Addl. Shelter Volunteers

Female Shelter Volunteer

First Aid Volunteer

Addl. First Aid Volunteer

Female Volunteer

Rescue Volunteer

Addl. Rescue

Volunteers

Relief

Volunteer

Addl. Relief

Volunteer

2-sq-km

2-3 Thousand people

UNIT

INVOLVEMENT OF COMMUNITY AND VOLUNTEERS

FOR CYCLONE MANAGEMENT

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CYCLONE PREPAREDNESS PROGRAMME (CPP) Government of Bangladesh and IFRCS

Disseminate cyclone warning signals issued by the Bangladesh Meteorological Department to the community people;

Assist people in taking shelter;

Rescue distressed people affected by a cyclone;

Provide First Aid to the people injured by a cyclone;

Assist in relief and rehabilitation operations;

Assist in implementation of the Disaster Preparedness Plan;

Assist in participatory community capacity build –up activities;

Assist in the coordination of disaster management and development activities

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Target planned numbers: 5000 (source: MoDMR)

Completed so far: 3739 (source: CDMP. Chittagong. : 1998,

Khulna+Barisal. : 1741)

Distribution: In some places distribution not much adequate.

In some places nearby centres are close, but in other places

much sparse.

What can be done??

Where no shelters. For the rest centres, shelters can be built where

no shelter at all.

Where shelters. Area should be filled up with shelters where shelters

are far apart.

CYCLONE SHELTERS (CURRENT SITUATION ON NUMBER AND DISTRIBUTION)

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Policy: Cyclone Shelters constructions, maintenance and

Management Policies 2011.

Multi-purpose, multi-storied. Mostly as educational

institutions

People and livestock both can take shelter. For livestock ramp

facilities walking up upper floors

What can be done??

Shelters with commercial benefit. Multipurpose multistoried

shelters can be built in bazars, hut ie, common place for

community. Ground floor can be used for shops. They can be

built on khas land, shops can be leased.

Shelters with mosque. Not everywhere, but in some strategic

location in case of foreign aided mosques, multistoried

mosque can be built keeping lowest/top floor reserved for

mosque, upper one as shelter.

CYCLONE SHELTERS (CURRENT SERVICES/PRACTICES)

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CONCLUDING REMARKS

Efforts to mitigate cyclone and storm surge disasters have

been successful (partial ?)

Science and Technology have contributed significantly in

reducing vulnerability

Forecasting and warning dissemination much more reliable

and efficient; use of cellular mobile phones should be

investigated

“Cyclone Preparedness Program” – success story of

Government-NGO partnership

Human deaths reduced significantly

Recommendations of MCSP (Multipurpose

Cyclone Shelter Programme )must be fully implemented

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Cyclones

Cyclones Synonyms

Cyclone Parameters

Classification of Cyclones

Cyclone Hazard Assessment

Cyclone

Areas Prone to Hurricanes/Cyclones/Typhoons

Tracks of cyclones in Bangladesh

Tracks of major cyclones

Prominent Storm Surge Since 1960

Major Cyclones and Storm Surge

Number of cyclonic storms landed in Bangladesh coast in different decades

Monthly distribution of cyclonic storms landed in Bangladesh coast between

1877 and 1990

Major Effects

Cyclone Categories (SoD, BD)

WHAT WE HAVE COVERED TODAY

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Possible Mitigatory Measures

Components of Cyclone Master Plan

Storm Surge Inundation

Recent Experience of Cyclone Shelters

Recent initiatives

Standing Orders on Disaster

Cyclone Warning Signals (SoD, BD, 2010)

Telecommunication During A Cyclone

Involvement of Community and Volunteers for Cyclone Management

Cyclone Preparedness Programme (CPP) Government of Bangladesh and

IFRCS

Cyclone Shelters (Current Situation on number and distribution)

Cyclone Shelters (Current Services/practices)

Concluding Remarks

WHAT WE HAVE COVERED TODAY

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WHAT WE LEARNT

Understanding of the fundamental concepts of Cyclones and storm surges, its consequences, and other contexts in Bangladesh.

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What Next?

Lecture 6: Disasters of Bangladesh: Earthquakes

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Sample Questions

1. Why wind damage is usually higher on the right of the track in the

northern hemisphere?

2. Classify cyclones as per BMD. Which one of cyclone categories based

on SoD and Saffir-Simpson Hurricane scale is more appropriate in

context of Bangladesh?

3. Explain the possible mitigating measures for cyclone management in

Bangladesh.

4. What are the components of Cyclone Master Plan?

5. What activities are covered presently under the Cyclone Preparedness

Programme (CPP) taken by Government of Bangladesh and IFRCS?