Megacity risks - Dhaka’s experiencePresentation

by

Professor Jamilur R. Choudhury

Vice Chancellor, University of Asia Pacific Dhaka, Bangladesh

atICRM Symposium, 2015

Institute of Catastrophic Risk ManagementNanyang Technological University, Singapore

23 April, 2015

Outline of Presentation� Megacity Dhaka : The setting

� Growth

� Natural Hazards

� Floods

� Earthquakes

� Manmade Disasters

� Building Collapse

� Political Violence

� Progress in risk reduction

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Bangladesh LocationDhaka – about 3,000 km northwest of Singapore

Megacity Dhaka – The setting � Capital of Bangladesh

� More than 400 years old

� Area : 1,528 sq. km.

� One of the fastest growing megacities in the world

� Population increased 4-fold in 25 years

� Current population : 16 million

� Growing @ 5% per year

� About 30% live in slums

� Surrounded by rivers

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� Dhaka City surrounded by rivers

� Eastern and Western fringes : low-lying water bodies, used to serve as flood retention ponds

� Being filled up rapidly by Land Developers

Major Natural Hazards � Natural Hazards

� Floods

� Overflowing rivers

� Heavy Rainfall – drainage congestion

� Earthquakes

� Extreme Winds

� Local thunderstorms

� Tornadoes

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Rainfall

� Annual rainfall : ≈ 2,000 mm

� ≈ 80% during monsoon (June-September)

� Maximum daily rainfall : 341 mm

Dhaka City Flood Inundation Map in 1998

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List of Major Earthquakes Affecting DhakaDate Name of

EarthquakeMagnitude(Richter)

Intensityat Dhaka

(EMS)

Epicentral Distance

from Dhaka (km)

10 January, 1869

Cachar Earthquake

7.5 V 250

14 July, 1885 Bengal Earthquake

7.0 VII 170

12 June, 1897

Great Indian Earthquake

8.7* VIII 230

8 July, 1918 Srimongal Earthquake

7.6 VI 150

2 July, 1930 Dhubri Earthquake

7.1 V+ 250

15 January, 1934

Bihar-Nepal Earthquake

8.3 IV 510

15 August, 1950

Assam Earthquake

8.5 IV 780

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Estimate of Building Damage and Corresponding Casualties

( Source : CDMP, 2010) � Scenario Earthquake : originating in Madhupur Fault,

about 100 km north of Dhaka

� Magnitude : Mw=7.5

� Buildings damaged

� Extensive to moderate damage ≈ 86,000

� Complete damage ≈ 72,000

� Casualties

� 88,000 (2 AM)

� 61,000 (2 PM)

Liquefaction SusceptibilityDhaka City

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EarthquakeVulnerability Reduction Efforts

� Procurement of Search and Rescue Equipment started

� Fire Service and Civil Defence personnel trained

� Contingency Plans for each government/semi-

government agency prepared

� Urban Volunteers : recruited and trained

� Retrofitting of important vulnerable buildings

� PWD Engineers trained

� Design and Construction Manuals being developed

Some Recent Building Disasters• 2005, 11th April : Spectrum Garments

Factory Collapse , 64 killed

• 2012, 24th November : Tazreen Fashions Fire, 117 killed

• 2013, 24th April, Rana Plaza Collapse; deadliest in recent world history; 1,135 killed; 3,000 injured

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Rana Plaza Before collapse After collapse

Reasons for Structural Collapse • Cracks appeared on 23rd April; building evacuated • Next morning, workers forced to resume work• Vibrations from emergency generators triggered

the collapse• Poor quality of concrete– strength around 1,500 pounds per square inch– perhaps half the strength assumed by designer

• part of foundation on loosely filled up water body• Designed as a commercial building; most floors

used for RMG industries• steel reinforcement inadequate; beam-column joints

weak

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Building Code � BNBC approved in 1993

� Legal enforcement in 2006

� Regulatory authority RAJUK unable to enforce the

code

� High Court has directed government to establish a

separate Building Regulatory Authority

Other Man-made disasters � Political Confrontation, “hartals” and road blockades

leading to “petrol bomb” attacks on vehicles

� During the last three months, number of people (mostly non-political)

� killed : around 100� injured : around 300

� Economic loss : approx. US$2.2 billion

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Concluding Remarks � Progress being made in reducing vulnerability

� Floods� Improved Flood Forecasting and Warning� Western part of Dhaka protected with

embankments

� Earthquakes� Vulnerable buildings identified� Some buildings being retrofitted� Urban volunteers being trained in search and

rescue

� Efforts to strengthen building regulatory authority

Thank you

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