Gizem Mestav Sarica, PhD CandidateProf. Pan Tso-Chien, ED-ICRM

Using Macro-Level Exposure Indicators for Future Disaster Risk Assessment in Megacities

Background & Aim• Following the rapid urban growth in recent years, exposure could be considered as themost dynamic

componentinriskassessmentprocesses.• Estimationofspatiotemporalchangeofexposureisacriticalandintricatetaskespeciallyformegacities

whicharecomplexsystemswithhighlosspotentials.• Theconventionallossestimationapproachesrequireadetailedinventorydatabaseofstructures.

Alternatively,macro-levelsocio-economicexposureindicatorsareused,relyingonregularlyupdateddata.• Thisstudyaimstoprojectthenaturaldisasterlossbasedonthespatiotemporalvariabilityofexposure,

assumingadirect relationbetween lossesdue tophysicaldamagesandbusiness interruption,and theeconomicproductivityofaregion.

Conclusions and Future Work• SLEUTHUrbanGrowthModelwasusedtoassessthespatiotemporalchangeinbuilt-upareaatrisk

forselectedmegacitiesconsideringdifferenttypesofnaturaldisasters.• Itwasobservedthateachcityisuniqueandshowsdifferenttrendsfrompasttofuture.However,the

increaseofbuilt-upareainhazardousregionsshouldbeassessedcarefullyfordisasterriskreduction.• Followingthebuilt-upareapredictionforfuture,grid-basedpopulationandGDPareplannedtobe

usedforfuturelossestimationofselectedmegacitiesconsideringdeterministicandprobabilisticseismichazardanalysisapproaches.

Contact Us: ExecutiveDirector,ICRM(ExecDir-ICRM@ntu.edu.sg)N1-B1b-07,50NanyangAvenue,Singapore639798Tel:+6565921866Website:http://icrm.ntu.edu.sg

www.ntu.edu.sg

References:-Opendataforresilienceinitiativefieldguide,GFDRR(2014)-SilvaEAandClarkeKC2002CalibrationoftheSLEUTHurbangrowthmodelforLisbonandPorto,PortugalComputers,EnvironmentandUrbanSystems26525–552-WaldDJ,QuintorianoV,HeatonTHandKanamoriH.1999RelationshipsBetweenPeakGroundAcceleration,PeakGroundVelocity,andModifiedMercalliIntensityinCaliforniaEarthquakeSpectra15557-564

What is Risk?

Urban Growth Prediction - 2030 Built-up Area at Risk

Methodology

Urban Growth Modelling

HAZARDThe likelihood, probability, or chance of a potentially destructive phenomenon

VULNERABILITYThe likelihood that assets will be damaged or destroyed when exposed to a hazard event

EXPOSUREThe location, attributes, and values of assets that are important to communities

RISK = HAZARD x VULNERABILITY x EXPOSUREThe composite of the impacts of ALL potential events

Built-upArea

Hazard

Built-up Area at

Risk

• As an initial step before the loss estimation, the change in built-up area at seismic risk and flood risk were obtained using the urban growth model projections for selected megacities, namely Istanbul, Jakarta, Metro Manila and Shenzhen.

• For this purpose, hazard maps obtained from different sources and built-up area from past, today and future are overlaid.

Aster GDEM Landsat

US

GS

Slope

Excluded Area

Transportation(At least 2 snapshots)

Urban Extent(At least 4 snapshots)

Hillshade

Test Mode

Coarse Calibration

Fine Calibration

Final Calibration

Prediction Mode

Urban Growth Prediction for 2030

QG

ISS

LEU

TH

Cal

ibra

tion

Mod

e Inputs

Jakarta

Metro Manila Istanbul Shenzhen

• Built-up Area at Seismic Risk was obtained for 10% Probability of Exceedance in 50 years for Jakarta, Metro Manila and Istanbul.

• Built-up Area at Flood Risk was obtained for Shenzhen.

Met

ro M

anila

Jaka

rta

Istanbul

Shenzhen

• Asaninitialstepbeforethelossestimation,thechangeinbuilt-upareaatseismicriskandfloodriskwereobtainedusingtheurbangrowthmodelprojectionsforselectedmegacities,namelyIstanbul,Jakarta,Metro Manila and Shenzhen.

• Forthispurpose,hazardmapsobtainedfromdifferentsources andbuilt-up area frompast, today and futureareoverlaid.

• Built-up Area at Seismic Risk wasobtained for 10% Probability ofExceedancein50yearsforJakarta,MetroManilaandIstanbul.

• Built-up Area at Flood Risk wasobtainedforShenzhen.

HAZARDThelikelihood,probability,orchanceofapotentiallydestructivephenomenon

VULNERABILITYThelikelihoodthatassetswillbedamagedordestroyedwhenexposedtoahazardevent

EXPOSUREThelocation,attributes,andvaluesofassetsthatareimportanttocommunities

RISK = HAZARD x VULNERABILITY x EXPOSUREThecompositeoftheimpactsofALLpotentialevents