Cyclone and Storm Surges

URP 4243: Hazards and Disaster Management
Lecture-05:
Disasters of Bangladesh: Cyclone and
Storm Surges
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Course Teacher:
Md. Esraz-Ul-Zannat
Assistant Professor
Dept. of URP, KUET
March 5, 2015
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
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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
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Cyclone Categories (SoD, BD)
TOPICS TO BE COVERED BY THIS PRESENTATION
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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
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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
 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
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CYCLONES SYNONYMS
Cyclones/Tropical Cyclones (Indian)
 Hurricane (Atlantic)
 Typhoon (Pacific)
 Kal Boishakhi/ Norwester (Bangladesh and part of India)
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CYCLONE
Radius of
Maximum Winds
(RMW)
Eye
Low pressure
Low winds
20-40 km or
more in
diameter
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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
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Up to 7.5 meters height
Moving up to 50 km inland
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CYCLONE PARAMETERS
 Winds
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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
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AREAS PRONE TO HURRICANES/CYCLONES/TYPHOONS
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TRACKS OF CYCLONES IN BANGLADESH
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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
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2
3
4
tropical depressions (TD) and tropical storms (TS)
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CYCLONE HUDHUD, OCTOBER 7-14, 2014
109 killed; loss US % 11 billion
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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
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Loss of human lives
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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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CYCLONE AND STORM SURGE
Cyclone
About 7% of the country
with a population of 10
million live in Risk Zone
In 1970,
300,000
people
1970
: 500,000
people
lost lost
theirtheir
liveslives
1991 : 138,000 human deaths,
property losses US $ 1.78 billion.
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CYCLONE CATEGORIES (SOD, BD)
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CYCLONE CATEGORIES
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POSSIBLE MITIGATORY MEASURES
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Evacuation
Embankments/Sea Walls
Afforestation
Strong Houses
Community Shelters
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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
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Solution : Community Shelters
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COMPONENTS OF CYCLONE MASTER PLAN
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Shelters
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Planning
Design
Construction
Maintenance
Management
 Community
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Development
Telecommunications
Public Awareness
Private Housing
Afforestation
Communication
Warning System
Lighting Energy
CPP Volunteers
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STORM SURGE INUNDATION
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Risk Zone
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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
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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
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Multistoried buildings on stilts
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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
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Multipurpose Cyclone and Storm Surge Shelter
(Red Crescent Society)
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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
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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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INVOLVEMENT OF COMMUNITY AND VOLUNTEERS
FOR CYCLONE MANAGEMENT
UNIT
VILLAGE
2-sq-km
2-3 Thousand people
UNIT COMMITTEE
Warning Group
Warning
Volunteer (L)
Addl. Warning
Volunteer
Shelter Group
Rescue Group
Rescue Volunteer
Addl. Rescue
Volunteers
First Aid Volunteer
Addl. First Aid Volunteer
Female Volunteer
First Aid Group
Relief Group
Relief
Volunteer
Addl. Relief
Volunteer
Shelter Volunteer
Addl. Shelter Volunteers
Female Shelter Volunteer
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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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CYCLONE SHELTERS (CURRENT SITUATION ON NUMBER AND DISTRIBUTION)
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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.
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CYCLONE SHELTERS (CURRENT SERVICES/PRACTICES)
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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.
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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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WHAT WE HAVE COVERED TODAY
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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
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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
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WHAT WE LEARNT
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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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