Bushfire Resilient Communities - ruralfire.qld.gov.au · 4.2.1 Creation of vegetation hazard class...

Bushfire Resilient Communities Technical Reference Guide for the

State Planning Policy State Interest ‘Natural Hazards, Risk and

Resilience - Bushfire’

October 2019

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Bushfire Resilient Communities – October 2019

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© State of Queensland, October 2019. Published by Queensland Fire and Emergency Services.

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Acknowledgement: QFES would like to extend its appreciation to the Department of State Development, Manufacturing, Infrastructure and Planning (DSDMIP), other State Government Departments, Local Governments, Industry Associations and individuals who contributed to the review process of these guidelines.

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Table of Contents

1. Purpose 5

2. Policy approaches 9

2.1 Context 9

2.2 Policy approaches 9

3. Background 11

3.1 State Planning Policy Interactive Mapping System approach 12

3.2 Factorsaffectingbushfirehazardandrisk 13

3.2.1 Potentialfirelineintensity 13

3.2.2 Fireweatherseverity 13

3.2.3 Slope 14

3.2.4 Fuelloadandvegetation 15

3.3 Potentialbushfireimpactsandattackmechanisms 15

3.3.1 Directflameattack 15

3.3.2 Heat exposure 16

3.3.3 Emberattack 17

4. Process for preparation and review of statewide SPP IMS bushfire prone area mapping 18

4.1 Introduction 19

4.2 MethodologyusedforpreparingtheSPPIMSbushfireproneareamapping 19

4.2.1 Creationofvegetationhazardclassandpotentialfuelloadmaps 19

4.2.2 Creationofslopemaps 19

4.2.3 Creationofpotentialfireweathermaps 19

4.2.4 Creationofpotentialfirelineintensitymaps 19

4.2.5 Creationofpotentialbushfireintensityandpotentialimpactbuffermaps 19

4.2.6 Modifypotentialintensityofsmallpatchesandcorridors 20

4.3 MethodologyforlocalgovernmentreviewofSPPIMSbushfireproneareamapping 23

4.3.1 Undertakereliabilityassessment 23

4.3.2 Locallyrefinemapping 23

5. Process for undertaking a Bushfire Hazard Assessment 25

5.1 Introduction 25

5.2 Overview:thethreestagesofaBHA 25

5.3 Stage1–Reliabilityassessment 25

5.3.1 Approach 25

5.3.2 Datasources 26

5.3.3 Procedure 26

5.4 Stage2–Hazardassessment 26

5.4.1 Approach 26

5.4.2 Procedure 27

5.5 Stage3–Separationandradiantheatexposure 28

5.5.1 Approach 28

5.5.2 Procedureforcalculating 28

6. Process for undertaking a Vegetation Hazard Class Assessment 29

6.1 Introduction 30

6.2 Process 30

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7. Process for calculating asset protection zones 39

7.1 Introduction 39

7.2 PurposeoftheBushfireassetprotectionzonewidthcalculator 39

7.3 Optionsforcalculatingtheradiantheatexposure 39

7.4 Bushfireassetprotectionzonewidthcalculatorcomponents 39

7.5 Bushfireassetprotectionzonewidthcalculatorinputparameters 40

7.5.1 Fireweatherseverity 40

7.5.2 Vegetationhazardclass(VHC) 41

7.5.3 Remnantstatus 41

7.5.4 Slopetype 41

7.5.5 Effectivefireslope 41

7.5.6 Siteslope 41

7.5.7 Distancefromhazardousvegetation 41

7.6 Parametricconstraintsandvariations 42

7.7 Bushfireassetprotectionzonewidthcalculatorsoftwareandhardwarerequirements 42

7.8 UsingtheBushfireassetprotectionzonewidthcalculator 43

7.9 Bushfireassetprotectionzonewidthcalculatorresults 43

7.10 Defaultassetprotectionzonewidthformula 44

8. Process for preparing a Bushfire Management, Vegetation Management or Landscape Maintenance Plans 45

8.1 Introduction 46

8.2 Managementplanreporting 46

8.3 BushfirehazardreportsandBushfireManagementPlans 46

8.4 VegetationManagementPlans 46

8.5 LandscapeManagementPlans 46

8.5.1 Landscapedesign 46

8.5.2 Plantselection 47

8.5.3 Landscapemanagement 48

8.5.4 Barriers 48

9. Information that may inform development conditions 49

9.1 Staticwatersupply 50

9.2 Assemblyandevacuationareas 50

9.3 Protectivelandscapetreatments 50

9.4 Assetprotectionzonesforvulnerableuses,storageormanufactureofmaterialsthatare 50 hazardousandcommunityinfrastructureforessentialservices

10. Expertise 51

10.1 Introduction 52

10.2 Suitablyqualifiedandexperienced 52

11. Acronyms and abbreviations 53

12. Glossary 54

13. Figures 56

14. References 57

51. PURPOSE

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1. Purpose

Thetechnicalguidanceinthisdocument,Bushfireresilientcommunities(BRC),supportstheStatePlanningPolicyJuly2017(SPP)andassociatedStatePlanningPolicystateinterestguidancematerial–Naturalhazards,riskandresilience–Bushfire(SPPguidance).

TheSPPoutlinesthestateinterestsinlanduseplanninganddevelopmentthatunderpinthedeliveryoflocalandregionalplansanddevelopment.Thesestateinterestsincludenaturalhazards,includingbushfire,andriskandresiliencemeasures.

TheSPPguidanceassists:

• localgovernmentstomakeoramendlocalplanninginstruments

• assessmentmanagersandpractitionerswhenapplyingtheSPPassessmentbenchmarkstodevelopmentapplications(onlywherethestateinterestshavenotbeenintegratedinlocalplanninginstruments).

TheBRCprovidestechnicalguidanceandthepolicypositionsofQueenslandFireandEmergencyServices(QFES)tostateagencies,localgovernments,andpractitionersengagedinlanduseplanningforbushfirehazardanddevelopmentactivitiesthatmaybeaffectedbybushfirehazard.Thisincludes:

• makingoramendingstateandlocalplanninginstrumentssuchasplanningschemesorregionalplans

• designatinglandforcommunityinfrastructure

• makingorassessingdevelopmentapplications.

Figure1,illustratestherelationshipbetweentheSPPandsupportingguidancematerial.

TheBRC:

• outlinesfactorsaffectingbushfirehazardandpotentialbushfirerisksandimpacts

• outlinesthemethodologyusedtopreparethestatewidemappingofbushfireproneareasincludedintheStatePlanningPolicyInteractiveMappingSystem(SPPIMS)

• providestechnicalguidanceonproceduresfor:

– reviewingSPPIMSbushfireproneareamapping

– undertakingaBushfireHazardAssessment(BHA)and VegetationHazardClassAssessment

– calculatingassetprotectionzoneprovisions

– preparingaBushfireManagementPlanandLandscape Maintenance Plan

• providesadditionalinformationtoinformdevelopmentconditions

• guidestheidentificationofsuitablyqualifiedpeopleforassessmentsidentifiedintheBRC.

ThisscopeissummarisedinFigure2.

Figure1:TherelationshipbetweentheStatePlanningPolicy(SPP)andtheSPPnaturalhazardsguidancematerial.

State Planning PolicyPart E state interest statement,

state interest policies & assessment benchamarks

Supporting Material

State interest: natural hazards, risk and resilience

SPP - guidance material - Natural hazards risk and resilience - bushfire

Bushfire resilient communities

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Figure2:Overviewofbushfireplanningandassessmentprocesses.

STATE SPP-IMS MAPPING METHODOLOGY:

LOCAL GOVERNMENT MAPPING REVIEW PROCESS:

DEVELOPMENT ASSESSMENT PROCESSES:

State Government initiated mapping

Local Government initiated review of state-wide SPP-IMS mapping

Applicant initiated site level verification by undertaking a Bushfire Hazard Assessment (BHA)

A new methodology for Statewide mapping of bushfire prone areas in Queensland (CSIRO, 2014) process

HazardassessmentSection 5 – 5.4

X X =

Fireweatherseverity–Section 3 – 3.2.2

Weather variables

Mapping tasks:

Forestfiredanger index

Climate change

Slope– Section

3 – 3.2.3

Create vegetation hazardclassandfuel loadmaps

Section 4 – 4.2.1

Create slope maps

Section 4 – 4.2.2

Create potential fireweather

maps Section

4 – 4.2.3

Create potential fireline

intensity maps

Section 4 – 4.2.4

Create potential firelineintensityandpotentialimpact buffer

maps Section

4 – 4.2.5

Modify potential

intensity of small patches andcorridor

Section 4 – 4.2.6

SPP-IMPmapping:

–Veryhighpotential bushfireintensity

–Highpotential bushfireintensity

–Mediumpotentialbushfireintensity

–Potentialimpactbuffer

Fuelload and

vegetation– Section

3 – 3.2.4

Potential firelineintensity–

Section 3 – 3.2.1

UndertakereliabilityassessmentSection 4 – 4.3.1 LocallyrefinemappingSection 4 – 4.3.2

Select representative

‘cells of interest’

Tally reliability

results

FollowtheprocessusedtocreateSPP-IMSmapping,usingimprovedlocalvegetationand/orslopemapping

consider suitability

of mapping

Assess reliability of BPAandVHC

mapping

Reliabilityassessment

Section 5 – 5.3

Vegetationhazardclass(VHC) assessment

Section 5 – 5.4 and Section 6

Prepare updated mapping–

Section 5 – 5.4.2

Re-calculate radiantheatflux levels–Section

5 – 5.5 and Section 7

Identify fire

weather severity

Identifysite slopeand effective

slope

DEVELOPMENT ASSESSMENT PROCESSES:

Reports documenting outcomes of Bushfire hazard assessment, and to demonstrate achievement of code assessment benchmarks

BushfireManagementPlan*(BMP)– Section 8 – 8.3

VegetationManagementPlan(VMP)– Section 8 – 8.4

LandscapeManagementPlan(BMP)– Section 8 – 8.5

Bushfirehazardreportdocumenting outcomesofBHA

2. POLICY APPROACHES8


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2.1 Context

Bushfirescancauseextensivesocial,economicandenvironmentaldamage.Withtheincreasingoccurrenceofdaysofextremeheatandfrequencyofseverefireweather,thepotentialimpactofbushfiresisofincreasingconcerninQueensland.Theimpactofbushfireswillvaryacrossthestate,dependingontheseverityofthebushfire,theproximityandexposureofpeopleandpropertytohazardousvegetation,andthevulnerabilityofdifferentlandusestobushfirehazard.Bushfireimpactscanaffectpeopleandpropertythroughflameattack,emberattack,radiantheatexposure,windandsmokeattack,andconvectiveandconductiveheatexposure.

Landuseplanningforbushfirehazardisonepartofanintegrateddisastermanagementstrategyinmitigatingtherisksassociatedwithbushfireeventstoanacceptableortolerablelevel.

2.2 Policy approaches

TheQFESpolicyapproachestolanduseplanningforbushfirehazardincludethefollowingtenpositions.

Policy 1 – Mapping is robust and locally relevant.

Asaminimum,theStatePlanningPolicyInteractiveMappingSystem(SPPIMS)bushfireproneareamappingmustbeidentifiedandappliedtolocalgovernmentplanningschemes.

LocalgovernmentsshouldrefinetheSPPIMSbushfireproneareamapping,usingtherefinementprocessoutlinedinthisdocument,andthenadopttherefinedmappingintheirspecificplanningscheme.QFESmaybeabletoassistlocalgovernmentswithlimitedresources,inthisprocess.

Policy 2 – A fit-for-purpose risk assessment informs plan-making or amendments to achieve an acceptable or tolerable level of risk to people and property in bushfire prone areas.

Localgovernmentsshouldundertakeariskassessmentwhenmakingoramendingaplanningscheme.

Tounderstandtheconsequencesofapotentialbushfireevent,theriskassessmentshouldconsidertheexposure,vulnerabilityandresilienceofcommunitiesandtheirassetstoabushfireasafirststepinproposingaplanningresponse.Ariskassessmentisamethodicalassessment,consideringthespecificcircumstancesofthelocalgovernmentarea.Preferably,theriskassessment:

• willbeconsistentwithAS/NZSISO31000:2018RiskManagement–PrinciplesandGuidelines1

• isundertakenbyasuitablyqualifiedperson(furtherdetailedinSection10).

Acomprehensiveriskassessmentmaynotberequiredforeveryplanningschemeamendment,dependingonthescopeoftheproposedinstrumentandwhetheranassessmenthasbeenpreviouslyundertaken.

QFEScanprovideadvicetolocalgovernmentsearlyintheplanningprocesstoscopeariskassessmentthatissuitedtothenatureoftheproposedschemeamendments(i.e.ariskassessmentthatisfit-for-purpose).Note–TheQueenslandGovernmenthasendorsedtheQueenslandEmergencyRiskManagementFramework(QERMF)asthestate’sapproachtoemergencyanddisasterriskmanagement.State–wideassessmentsconductedunderthisframeworkprovidekeyinformationrelevanttolocalassessments,andareheldbyLocalorDistrictDisasterManagementGroups.

Policy 3 – The planning scheme or amendments following a risk assessment are based on the principle of avoidance as the first priority, and then mitigation of the risk to an acceptable or tolerable level.

Theoutcomesoftheriskassessmentshouldinformthedraftingofthelocalplanningstrategicframeworkandassessmentbenchmarkstoensureaclearapproachtomanagingbushfirerisk.

Avoidanceoftheriskwouldincludealocalgovernmentminimisingtheexpansionorincreaseddensityofexistingdevelopmentinmappedbushfireproneareas,particularly:

• vulnerableuses

• communityinfrastructureforessentialservices

• materialsthatarehazardousinthecontextofbushfirehazard.

Afterthis,managingbushfireriskshouldbebasedonachievinganacceptableortolerablelevelofriskforbothexistingandnewdevelopmentinbushfireproneareas.

Anacceptable riskisalevelthatissufficientlylowtorequirenonewtreatmentsoractionstoallowcommunitiestolivewiththeriskwithoutfurtheraction.

Atolerable riskislowenoughtoallowtheexposuretoanaturalhazardtocontinuebuthighenoughtorequirenewtreatmentsoractionstoreducethatrisk.Communitiescanlivewiththislevelofrisk,butasmuchasisreasonablypracticalshouldbedonetoreducetherisk.Thismayincludeplanningresponsesfor:

• reducingthelikelihoodoftherisk(avoidance)

• reducingtheconsequencesoftherisk(mitigationandhazardmanagementovertime).

Whatconstitutesanacceptableortolerablelevelofriskwillvaryamonglocalgovernmentareasandcommunitycontext.Ifappropriate,communityconsultationcouldbeundertakentounderstandtolerancelevelstobushfireriskandidentifypossibletreatmentoptions.Note–Otherresponsesmayalsobesuitableforimplementationviaspecificlocalgovernmentinstrumentssuchaslocallawsorassetmanagementplans.

Policy 4 – Disaster management capacity and capabilities are maintained to mitigate the risks to people and property to an acceptable and tolerable level.

Mitigationinvolvesalocalgovernmentincludingprovisionsinitsplanningschemetoensuresubdivisionlayout:

• locateslowfuelseparationareas,suchasroads,managedopenspacesandlargelots,toseparatepeoplefromhazard

• doesnothinderemergencyserviceaccessandfunctionsthroughactivemeasuresincluding:

– ensuringsufficientaccessareas(e.g.viaperimeterroads orfiretrailandworkingareas)forfirefightersand vehiclesbetweenassetsandvegetation

– allowingforvegetationmanagementandwildfire responsetoprovideopportunitiestoestablish controllinesfromwhichhazardreductionorback- burningoperationscanoccur

2. Policy approaches

1 It is acknowledged that ISO 31000–2018 is a generic standard for a broad range of risk assessments.

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• allowssafeaccessandegressroutes

• ensureswatersupplyinbothreticulatedandnon-reticulatedareas.

MitigationalsoinvolveslocalgovernmentsincludingprovisionsintheirplanningschemeforBushfireManagementPlans(BMPs)forongoingvegetationmanagementthatmaintainsidentifiedlowfuelseparationareas.

Policy 5 – Lot and neighborhood layout and design mitigates the risks to people and property to an acceptable and tolerable level.

Mitigationinvolveslocalgovernmentsincludingprovisionsintheirplanningschemefor:

• newsubdivisiondesigntominimisetheinterfacewithbushfireproneareasandfacilitateconnectionstosafeevacuationroutes

• landscapedesignandmanagementthatdoesnotincreasethelevelofbushfireriskormechanismsofbushfireattack.

Thekeymitigationapproachforhousesinvolvealocalgovernmentdefiningallorpartofitsareaasadesignatedbushfireproneareainaccordancewithsection12oftheBuildingRegulation2006.ThisinturntriggerstherequirementforadherencetoAustralianStandard3959–2018Constructionofbuildingsinbushfire-proneareasatthebuildingdevelopmentapplicationstage.

Policy 6 – Vulnerable uses are not located in bushfire prone areas unless there is an overwhelming community need for the development of a new or expanded service, there is no suitable alternative location and site planning can appropriately mitigate the risk.

Thelocalgovernmentshouldincludeprovisionsinitsplanningschemewhicharticulatethispolicyposition.

Iflocatedinabushfirepronearea,vulnerableusesmaintaindisastermanagementcapacityandcapabilities,andmitigatetheriskstopeopleandpropertytoanacceptableandtolerablelevel(seePolicy4).

Policy 7 – Revegetation and rehabilitation avoids an increase in the exposure or severity of bushfire hazard.

Localgovernmentsshouldincludeprovisionsintheirplanningschemeswhicharticulatethispolicypositionanddonotresultinanunacceptablelevelofriskoranincreaseinthepotentialbushfireintensitylevel.

Policy 8 – Development does not locate buildings or structures used for the storage or manufacture of materials that are hazardous in the context of a bushfire within a bushfire prone area unless there is no suitable alternative location.

Thelocalgovernmentshouldincludeprovisionsinitsplanningschemewhicharticulatethispolicyposition.

Iflocatedinabushfirepronearea,theriskstopublicsafetyandtheenvironmentfromthereleaseofthesematerialsduringandafterabushfireeventmustbemitigatedbypositioningit:

• outsideanyassetprotectionzoneapplyingtootherbuildingsorstructuresonthesite

• asclosetotheedgeofthebushfireproneareaaspossible.

Iflocatedinabushfirepronearea,thestorageormanufactureofmaterialsthatarehazardousinthecontextofabushfiremustbemanagedthrough:

• maintenanceofappropriatedisastermanagementcapacityandcapabilities

• mitigationoftheriskstopeopleandpropertytoanacceptableandtolerablelevel(seePolicy4).

Policy 9 – The protective function of vegetation arrangements that can mitigate bushfire risk are maintained.

LocalgovernmentsshouldincludeprovisionsintheirplanningschemestomandateBMPsthatupholdtheprotectivefunctionofvegetationarrangements,suchasspeciesselection,landscapedesignandongoingvegetationmanagement.

Policy 10 – Community infrastructure for essential services are not located in bushfire prone areas unless there is an overwhelming community need for the development of a new or expanded service and there is no suitable alternative location, and further, the infrastructure can be demonstrated to function effectively during and immediately after a bushfire event.

Localgovernmentsshouldincludeprovisionsintheirplanningschemeswhicharticulatethispolicyposition.

Iflocatedinabushfirepronearea,communityinfrastructureforessentialservicesmustbesecuredby:

• maintenanceofappropriatedisastermanagementcapacityandcapabilities

• mitigationoftheriskstopeopleandpropertytoanacceptableandtolerablelevel(seePolicy4).

113. BACKGROUND

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3. Background

3.1 State Planning Policy Interactive Mapping System approach

TheStatePlanningPolicyJuly2017(SPP)identifiesbushfireproneareasasthosewithamediumpotentialbushfireintensity,highpotentialbushfireintensityorveryhighpotentialbushfireintensitywithanadditional100metrepotentialimpactbuffer,representingthatpartofthelandscapethatcouldsupportasignificantbushfireorbesubjecttosignificantbushfireattack.

Bushfireimpactsinabushfireproneareaarepotentiallyharmfultopeopleandproperty.

Theareasmappedasmedium,highorveryhighpotentialbushfireintensityintheStatePlanningPolicyInteractiveMappingSystem(SPPIMS)bushfireproneareamappingincludepotentiallyhazardousvegetationthatcouldsupportasignificantbushfire.Theseareashavea4,000–20,000,20,000–40,000or40,000+kW/mpotentialfirelineintensityrespectively(furtherdescribedinSection3.2.1).

Bushfiresintheseareashavethepotentialforhightoextremelevelsofflameattack,radiantheatandemberattackasaresultofhighpotentialfuellevels,slopeandfireweatherseverity.

PotentialimpactbufferareasintheSPPIMSbushfireproneareamappingcompriselandadjacenttopotentiallyhazardousvegetationthatisalsoatriskofsignificantbushfireattackfromembers,flamesorradiantheat.Potentialimpactbufferareasincludealllandwithin100metresofareasmappedasmedium,highorveryhighpotentialbushfireintensity.This100metrewidthwasinformedbyfindingsindicating78percentoffatalitiesoccurwithin30metresand85percentoffatalitiesoccurwithin100metresofhazardousvegetation(theforestedge)inAustralia.2

Themappingofthesetwodifferentlayers–potentialintensityandimpactbufferareas–identifiesthepotentialseverityofbushfiresandtheirpotentialexposureasseenbelowinFigure3.

Potential Impact Buffer

High Potential Bushfire Intensity

Figure3:Exampleofamappedbushfirepronearea,includingthepotentialimpactbuffer (landwithin100linearmetresofmappedvegetationofgreaterthan4,000k/Wmfirelineintensity).Source:SPPIMS

2 Life and house loss database description and analysis - https://publications.csiro.au/rpr/download?pid=csiro:EP129645&dsid=DS2

https://publications.csiro.au/rpr/download?pid=csiro:EP129645&dsid=DS2

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3.2 Factors affecting bushfire hazard and risk

3.2.1 Potential fireline intensity

AnewmethodologyforstatewidemappingofbushfireproneareasinQueensland(CSIRO,2014)3,4,5,usedtoproducethecurrentstatewideBushfireProneAreamapimproveduponthepreviousSPP1/03bushfirehazardmappingmethodologyapproachbyprovidingmorein-depthconsiderationofregionaldifferencesinfireweatherseverityanddiversityofvegetationtypes.Accordingly,bushfireproneareaswereidentified,mappedandcategorisedasafunctionofpotentialfirelineintensity(kW/m).

Potentialfirelineintensityisafunctionoffireweatherseverity(measuredbytheForestFireDensityIndexorFFDI),landscapeslopeandfuelload(referFigure4)basedonclassifiedvegetationcommunitiesaccordingtothemethoddescribedbytheCSIROmethodologycitedabove.

Firelineintensityisameasureofenergyreleasedfromtheflameorcombustionzone,oneofwhosesidesisaunitlengthoffirefront(measuredinkilowattspermetreofflamingfront).7 The intensitydependsontheheatofcombustionofthefuel,theforwardrateofspreadandtheamountoffinefuelconsumedintheflamingfront.Thisisagoodpredictoroftheavailableenergythatcanbereleasedfromafirebasedoncertainweather,fuelandtopographicalinformation.Theimpactofthisreleasedenergyaffectsthesuccessofsuppressioneffortsandscaleofdamage.

Potentialfirelineintensityisastandardisedmeasureoftheratethatanadvancingheadfirewouldconsumefuelenergypersecond,permetreofthefirefront.8

Areasidentifiedasamedium,highorveryhighpotentialbushfireintensityintheSPPbushfireproneareamappinghavea4,000k/Wm+firelineintensity.

Afirelineintensityof4,000 kW/misestimatedtobetheapproximatethresholdfortheeffectiveandsafedirectattackonaheadfirewithaircraftandmachineryasveryvigorousorextremelyintensesurfacefirecontroleffortsonheadmayfailandbedangerous.9

Thethresholdforcontinuouscrownfireis10,000 kW/m. Controlinthisscenarioisextremelydifficultandalleffortsatdirectcontrolarelikelytofail.Directattackisrarelypossible.Suppressionactionmustberestrictedtotheflanksandbackofthefire.10

Crownfireshavethepotentialtodramaticallyincreasefireintensitywiththeadditionofthecrownfuelandchangestothewindfield.Thiswillproducearelatedincreaseinemberproductionandspotting.

Firelineintensitygreaterthan30,000 kW/miscommonlyunderstoodasblow-upconditions.Intensitiesexceeding30,000kW/mwereadefiningfeatureofthe2009BlackSaturdayFires.11

Vegetatedpartsofthelandscapethatwouldcarryavegetationfireataintensitylowerthan4,000kW/marecategorisedasgrassfirepronelandorlowhazardareas(e.g.rainforestorwateror

non-vegetatedurbanareas).Intheeventofafire,directmanualattackatfire’sheadorflanksbyfirefighterswithhandtoolsandwaterispossible.Thisistheleveloffirelineintensitywheremostplannedburningtakesplace.

Verylittlespotfireactivityoccursatlessthan1,000kW/m.12 Constructedbreaksshouldholdfiresattheupperendofthescale,however,willstillbechallengingifthefuelsarepronetoemberproductionandspotting.13

3.2.2 Fire weather severity

Fireweatherseverity(FWS)forlanduseplanninginQueenslandisdeterminedusingthreeinputsunderthemethodology.Theseareweathervariables,FFDIandclimatechange.

Weather variables

FWSisinfluencedbyarangeofweathervariablesincludingwindspeed,relativehumidity,temperatureandatmosphericstability,aswellprecedingdroughtconditions.

Windsincreasetherateoffirespreadby‘driving’ortiltingflamesforward,increasingtherateatwhichtheunburntfuelsaheadofthefirearepreheated,thusincreasingtherateofspreadandtheintensityofbushfires.14

Windandconvectiveupdraughtscarryburningembersaheadofthefirefront.Embersaremainlyburningfragmentsofbark,leavesandtwigs,whichhavethepotentialtoignitenewfiresinsuitablyrecipientfuelsand/orinfrastructure.Strongwindscanalsocauseburningtreesorbranchestostrikebuildingsorfencesandblockaccessandevacuationroutes.

3 Leonard, J., Newnham, G, et al. (2014), A new methodology for State-wide mapping of bushfire prone areas in Queensland.4 The method for determining potential fireline intensity for small patches and corridors of vegetation has been refined as

described in Leonard, J. and Opie, K (2017), Estimating the potential bushfire hazard of vegetation patches and corridors.5 Potential fuel loads and vegetation hazard classes were updated for SEQ in 2017, information available from QFES. 6 Leonard, J., Newnham, G, et al. (2014), A new methodology for State-wide mapping of bushfire prone areas in Queensland.7 Byram, GM (1959), Combustion of forest fuels and Tangren CD (1976), The trouble with fire intensity.8 Leonard, J. and Blanchi, R (2012), Queensland bushfire risk planning project.9 Alexander and DeGroote (1989) https://fireandemergency.nz/assets/Documents/Research-and-reports/Report-21-Fire-

Behaviour-as-a-factor-in-Forest-and-Rural-Fire-Supression.PDF10 Ibid.

11 Cruz et al. (2015), Empirical based models for predicting head fire rate of spread in Australian fuel types.12 Gould et al. (2008), Project Vesta: Fire in Dry Eucalypt Forest: Fuel structure, Fuel Dynamics and Fire Behaviour.13 Alexander and DeGroote (1989) https://fireandemergency.nz/assets/Documents/Research-and-reports/Report-21-Fire-

Behaviour-as-a-factor-in-Forest-and-Rural-Fire-Supression.PDF14 Byram, GM (1959), Combustion of forest fuels.

Figure4:Methodforcalculationofpotentialfirelineintensity.6

FUEL LOAD

FIRE WEATHER SEVERITY

POTENTIAL FIRELINE

INTENSITYSLOPE

https://fireandemergency.nz/assets/Documents/Research-and-reports/Report-21-Fire-Behaviour-as-a-fact




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Relativehumidity(RH)istheratioofmoistureactuallyintheairversusthemaximumamountofmoisturewhichtheaircouldholdatthesametemperature.RHisameasureofthedryingpoweroftheairandthisaffectsthefinefuelmoisturecontent.RHisexpressedasapercentagewithmoisturesaturation(fog)being100percent.Asaircanholdmoremoistureathighertemperatures,theRHalonedoesnotgiveanabsolutemeasureofmoisturecontent.

WhentheRHishigh,thefinefuelsabsorbmoisturefromtheatmosphere.Underdryingconditions(decreasingRH),themoistureofthefinefuelsisdesorbedtotheatmosphere,loweringthefinefuelmoisturecontentandincreasingthelikelihoodoffireignition.Verylowlevelsofhumiditysupportextremebushfirebehaviour.

Airtemperaturealsoplaysasignificantroleinaffectingatmosphericconditions,windsandfuelmoisturecontent.

Weathervariablesdonotoperateinisolationfromeachother(orotherfactorsthatinfluencefirebehaviour).Forexample,lowhumiditycoupledwithhightemperaturesandhotwindsdryoutvegetation,increasingbushfirepotential.

Forest Fire Danger Index

TheMcArthurForestFireDangerIndex15(orFFDI)isthemostcommonproxyoffireweatherseverityinAustraliaandisusedforbushfirehazardassessments,emergencymanagementandinregulationssuchastheAustralianStandard3959–2018Constructionofbuildingsinbushfire-proneareas.

UnlikeQueensland’sadoptionofAS3959–2018thatusesasingleFFDIvalueforallofQueensland(40),theestimateoffireweatherseverityusedasaninputtoidentifyingtheSPPbushfireproneareasinQueenslandrecognisesthatweatherconditionsvaryacrossthestate.

Spatiallyexplicit5%annualexceedanceprobability(AEP)fireweathereventFFDIvaluesforQueenslandhavebeenestimatedfromagridded(83kilometre,three-hourlyresolution)predictionofFFDIfromlong-termspatialweatherproductsproducedbytheAustralianBureauofMeteorology(BoM).16 TheadoptedFFDIvaluesreflecta5%AEPweatherevent.AdoptedFWS(i.e.5%AEPfireweathereventFFDI)valuesforQueenslandvaryfrom50inSoutheastQueenslandandCapeYorkbioregionsto130inthesouth-westernpartsofthestate.17

Theidentificationoflocation-specificFWSforthepurposesofdeterminingbushfirehazardisdescribedinsection5.4.2ofthisdocument.SPPmappingdataofFWScanbeobtainedinrasterformatfromtheQueenslandGovernmentdata portal underthetitle‘Bushfirehazardarea–Bushfire-pronearea–inputs–Queensland’.

Climate change

Climatechangeprojectionsindicateanincreaseinthelikelihood,intensityandextentofareasaffectedbybushfiresandextendedfireseasons.ClimatechangeprojectionswereincorporatedintotheSPPmappingofbushfireproneareas.

Thiswasachievedbyincorporatinganadjustmenttothegriddedweathertemperatureandrelativehumiditydatausedtocalculate5%AEPfireweathereventFFDItoreflecttheexpectedclimatein2050usinganIntergovernmentalPanelonClimateChangeA1FIclimatescenario.18

3.2.3 Slope

Theslopeofthelandisamajordeterminantoffirebehaviour,particularlytheslopeofthelandundervegetationthatcontributestobushfirehazard.

Fireburnsfasterasittravelsupaslope,viapreheatingofunburntfuelsaheadofthefire,increasingtherateofspreadandfirelineintensity.Conversely,firesmovemoreslowlyastheytraveldownslope.Firelineintensity(kW/m)isafunctionoftherateofspread.19

Asageneralrule,therateoffirespread(andfirelineintensity)doublesupa10-degreeslopeandquadruplesupa20-degreeslopeoftheland.20,21

Whereslopeunderhazardousvegetationislocateddownhillfromtheedgeofthehazardousvegetationnearesttotheassetlocation,itisconsidered‘downslope’irrespectiveoftheslopeoflandbetweentheassetandtheedgeofthehazardousvegetation.

Wheretheslopeunderhazardousvegetationislocateduphillfromtheedgeofthehazardousvegetationnearesttothesite,itisconsidered‘upslope’irrespectiveoftheslopeoflandbetweenthesiteandtheedgeofthehazardousvegetation.

Accordingly,developmentlocatedabovehazardousvegetation(thevegetationis‘downslope’)istypicallysubjecttohigherlevelsofpotentialemberattack,radiantheat,convectiveheatingandlongerflamelengthsthandevelopmentwhichislocatedbelowhazardousvegetation(thevegetationis‘upslope’).

Astatewide25metreresolutiondigitalterrainmodel(DTM)wasusedtoproduceastatewidemapofmaximumlandscapeslope,representingthemaximumpotentialslopeofthelandscapewhichcouldinfluencetherateofbushfirespreadandfirelineintensity.22TheSPPmapofmaximumlandscapeslopecanbeobtainedinrasterformatfromtheQueenslandGovernmentdataportalunderthetitle‘Bushfirehazardarea–Bushfire-pronearea–inputs–Queensland’.

Themethodologyusedinsection5describesproceduresformeasuringlocalisedslopewhendeterminingsuitableassetprotectionzonewidthsfromhazardousvegetation.

15 McArthur, AG (1967), Fire behaviour in eucalyptus forests.16 Leonard, J., Newnham, G, et al. (2014), A new methodology for State-wide

mapping of bushfire-prone areas in Queensland.17 Ibid.18 Ibid.

19 Byram, GM (1959), Combustion of forest fuels.20 Assumes that slope and wind direction are aligned.21 Leonard, J. and Blanchi, R (2012), Queensland bushfire risk planning project. 22 Byram, GM (1959), Combustion of forest fuels.

15

3.2.4 Fuel load and vegetation

Vegetationistheprimarysourceoffuelandcombustionoffuelpowersabushfire.

Ingeneral,vegetationcommunitieswithahigherquantityoffuelavailabletoburn(i.e.fuelload)willtendtogiverisetohigherintensityfiresandpresentahigherrisktopeopleandproperty.However,thefuelarrangementandcomposition,notjustthequantity(load)alsocontributestotherateoffirespreadandfirelineintensity.Onlytotalfuelloadisusedinthisplanningprocess.

UndertheSPP’splanningparameters,thepotentialfuelloadthatavegetationcommunitywouldnormallyaccumulate10yearsafterafireisusedtoestimatethefirelineintensityandbushfirehazard,nottheactualfuelloadonanyparticulardayoryear.Thisapproachensuresconsistencyinplanninganddesign.

Thepotentialfuelloadrepresentstheambientfuelloadthatiscombustibleundersevereweatherconditions.Itiscalculatedasthesumofsurfacefuelload,near-surfacefuelload,elevatedfuelloadandstandingbarkfuel.Thepotentialfuelloadrepresentsthe80thpercentilefuelloadforeachfuelcategorybasedonthelong-termunburntcondition.23

Long-termandsustainedreductionoffuelloadbyclearing,cultivationormanagementofvegetationreducesthepotentialfirelineintensityandhazardlevel.

Theavailabilityoffuelisafunctionofitsmoisturecontent,type,structure,arrangementandthesizeandseverityofthefire.

Finefuelload,structureandcomposition,isdescribedusingaseriesofvegetationhazardclasses(VHCs).VHCsarebasedontheQueenslandHerbarium’sstatewideregionalecosystemmappingatthebroadvegetationgroup24level,andseveralothermappingdatasetssuchasfoliageprojectivecovermapping.

Hazardousvegetationwithinruralandurbanlandscapesisfrequentlyfragmented,givingrisetosmallerpatchesandnarrowcorridorsofvegetationthatareverylikelytohavelowerfirelineintensitiesthanlargerexpansesofcontinuousvegetation.

Thespatialcontextofthesepatchesandcorridorsofvegetationhasamajorinfluenceonthelikelihoodoffirearrival,theseverityofafireattheboundaryofthepatch,andthebehaviourofafirewithinthepatch.

Becauseofthepotentialcontributionofgrassfirestotheintensityoffireintree-orshrub-dominatedhazardousvegetation,bushfirehazardassessmentofpatchesandcorridorsneedstotakeaccountofthefuelpropertiesofadjacentvegetationorotherlanduses.

Continuousvegetation,suchasforest,shrublandorgrass,hasagenerallyuniformdistributionoffuelthatsupportsacontinuousflamefrontunderarangeofweatherconditions.Incontrast,non-continuousvegetationorlanduses,suchasbuilt-upareasorwaterbodies,arenotexpectedtosupportacontinuousflamefrontbecausetheydonotcontainsufficientfuelloadtocarryafire.

TheSPPVHCandassociatedpotentialfuelloadinputdatacanbeobtainedinshapefileformatfromtheQueenslandGovernmentdataportalunderthetitle‘Bushfirehazardarea–Bushfire-pronearea–inputs–Queensland’.TheformatforVHCcategorizationinQueenslandisdescribedinFigure6.

3.3 Potential bushfire impacts and attack mechanisms

Themainsourcesofdirectbushfireattackthatgiverisetolossoflife,anddamagetopropertyandinfrastructureare25:

• directflamecontact

• radiantheatexposure

• convectionandconduction

• emberattack

• windandsmokeattack.26

Theseattackmechanismsarenotmutuallyexclusiveandrarelyoperateinisolation.Peopleandpropertyareoftensubjecttoacombinationofbushfireattackvectors.

Althoughbushfireattackvectorsoperateatarangeofspatialscales,measurestoreduceormitigatetheeffectsofdirectflamecontact,radiantheatexposureandemberattackoccuratscalesthatcanbeaddressedvialanduseplanninganddevelopmentassessmentframeworks.Thefollowingsectionsdescribethesethreebushfireattackmechanismsandtheirpotentialimpacts.

3.3.1 Direct flame attack

Directflamecontactoccurswhenflamesfromabushfireareindirectcontactwithabuilding,structureorpeopleresultinginignition,burnsandradiantheatexposureeffects(‘flamezone’).Directflamecontactisonlyanissuefordevelopmentthatisdirectlyadjacenttobushfireproneareas.Directflamecontactcancause:

• rapid,pilotignitionoffuelandstructuresconsistingofflammablematerialssuchastimberfences,powerlinepolesandtimberhomes

• burnstoexposedskin.

Flamecontacthasobviousandsignificantimpactsonpeople,propertyandemergencyservices.

23 The long-term unburnt condition represents greater than 10 years without burning. For further information see Leonard, J., Newnham, G, et al. (2014), A new methodology for State-wide mapping of bushfire-prone areas in Queensland.

24 Neldner, VJ, and Niehus et al. (2015), The vegetation of Queensland: Descriptions of broad vegetation groups.25 Leonard, J. and Blanchi, R (2012), Queensland bushfire risk planning project. 26 Wind attack is an indirect or secondary source of bushfire attack. Wind-driven attack may extend flame lengths and height, increasing ignition likelihood and radiant

heat exposure. Wind is also responsible for promulgating burning embers and smoke. Although smoke has a negligible impact on buildings and structures, direct impacts on civilians and emergency services can be significant in terms of health and visibility.

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3.3.2 Heat exposure

Heattransferoccursviathreeprocesses:

1. Convection:thetransferofheatviathemovementofhotair.Undercertaincircumstances,bushfirescangeneratesufficientheattomodifytheatmosphericconditionsaroundthefire,creatingaconvectioncolumnthatcantransportembersandburningdebris.Thisrepresents60percentto80percentofthetotalheatgeneratedbyabushfire.

2. Conduction:thetransferofheatwithinthefuelitself.Thisissignificantduringtheinitiationofabushfirebutinsignificantintermsofradiantheatexposure.Thisrepresentsabouttwopercentofthetotalheatgeneratedbyabushfire.

3. Thermalradiationorradiantheat:thetransferofheatbymeansofelectromagneticwaves.Thetransferofheatbyradiationinvolvesthecarryingofenergyfromanorigintothespacesurroundingitinstraightlinesinalldirections.Theenergyiscarriedbyelectromagneticwavesanddoesnotinvolvethemovementortheinteractionofmatter.Thisrepresents20percentto40percentofthetotalheatgeneratedbyabushfire.

Exposuretoradiantheatcan:

• distort,crackandwarpmaterials(e.g.glasswindowsandplastictanks)leadingtostructuralfailureandprovideopportunitiesforemberattack

• causeignitionofexposedmaterialssuchaswalls,fencesandpowerlinepoles

• limittheabilityofemergencyservicestosafelyoperate(refertoFigure5)

• causedeathorinjurytopeople,evenatlowlevelsofradiationexposure(refertoFigure5).

Thepotentialimpactsofradiantheatexposureonpeople,propertyandemergencyservices(expressedasradiantheatflux,kW/m2)areindicatedinFigure5.

Evidencesuggeststhatfatalitiesinsidestructuresarestronglyassociatedwithhighlevelsofradiantheatexposureandpossibleflamecontact.27,28

27 Blanchi, R, Leonard, J, et al. (2012), Life and house loss database description and analysis: Final report. 28 Blanchi, R, Leonard J, et al. (2014), Environmental circumstances surrounding bushfire fatalities in Australia 1901-2011.29 Subject to exposure time, timber species and dryness of timber.30 Blanchi, R, Leonard, J, et al. (2012), Life and house loss database description and analysis: Final report. 31 NSW Rural Fire Service (2010), Planning for bush fire protection.

Radiant heat flux (kW/m2) Potential effects

Greater than 40

• unpilotedignitionoftimberwallsandfences

• directflamecontactlikely

• extremelevelsofradiantheat

29–40

• failureoftoughenedglass

• directflamecontactpossible,extremelevelsofradiantheat

• unpilotedignitionofsometimberspeciesafterprolongedexposure(e.g.severalminutes)29

19 • failureofscreenedfloatglass

16 • blisteringofskinwith>5secondsexposure

12.5• failureofplainglass

• pilotedignitionofdrytimberelementsafterprolongedexposure(e.g.severalminutes)30

10

• fabricsinsideabuildingcouldignitespontaneouslywithlongexposure

• criticallimitforemergencyservices–firefighterscannotoperate

• lifethreateningwith<1minuteexposureinprotectiveclothing.

7 • fataltoanunprotectedpersonafterexposureforseveralminutes

4.7 • firefighterinprotectiveclothingwillfeelpain(60secondsexposure)

3 • firefighterscanoperateforashortperiod(10minutes)

2

• painisfeltonbareskinafter1minuteexposure(non-fatal)

• firefighterswithprotectiveclothingcanwithstandthisexposurelevelforafewminuteshowever, theyarelikelytoexperienceriseincorebodytemperature

1 • maximumforindefiniteskinexposure

0.5 • directsunlightatnoononabrightsunnyday

Figure5:Potentialeffectsofradiantheat.31

3.3.3 Ember attack

Embersaresmallpiecesofburningfoliage,twigsandbarkwhicharetransportedbywind,oftenaheadofthefirefront.Themainsourcesofembersaretreebark,finelitterandotherfinefuels.

EmberattackisthemaincauseofdamagetoandlossofhousesinAustraliaduetobushfire.Burningor‘live’embersareproblematicbecausetheycan:

• Travellongdistancesandleadto‘spotting’bystartingnewfiresaheadofthefirefront(includingfuelsourcesaroundhomessuchasfences,outdoorfurnitureandsurfaceandnear-surfacefuelsingardens)upto40kilometresundersevereconditions;however,80percentof‘spotting’occurswithin100metresofhazardousvegetation.

• Penetratesmallgapsandholes,infiltratingbuildingsandstructures,resultinginsingleormultiplesourcesofignition.

• Accumulatearoundvegetation,buildingsorotherstructures(e.g.roofgutters,decksandpatios),resultinginslowonsetignitionwhichcanthenengulfbuildingsandstructuresduringorafterafirefrontpasses.Theaccumulationofembersandemberdensityareestimatedtoberesponsibleforupto90percentofignitionsleadingtobuildinglossinanurbanenvironment.32

Throughspotting,embersareamajorcontributortothefailureoffirecontainmentmethodsandsuppression.Thiscanhavedirectimpactsonpeopleandpropertyduringabushfire.

1732 Blanchi, R, Leonard, J, et al. (2012), Life and house loss database description and analysis: Final report.

4. PROCESS FOR PREPARATION AND REVIEW OF STATEWIDE SPP IMS BUSHFIRE PRONE AREA MAPPING

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19

4.1 Introduction

TheStatePlanningPolicyJuly2017(SPP)identifiestheStatePlanningPolicyInteractiveMappingSystem(SPPIMS)bushfireproneareamappinglayerasatooltobelocalisedfor,andappropriatelyintegratedinto,localgovernments’planninginstrumentsinawaythatachievesthestate’sinterest.

Insomecircumstances,thebushfireproneareafootprintmaychangeafterlocalverification,moreaccuratelydepictingpotentialbushfirehazard.Thisprovidesahigheraccuracyproducttoinformhazardandriskassessmentprocessesfordecisionmakers.

4.2 Methodology used for preparing the SPP IMS bushfire prone area mapping

ThecreationoftheSPPIMSbushfireproneareamappinginvolvedthefollowingstepsandprocesses.

4.2.1 Creation of vegetation hazard class and potential fuel load maps

Vegetationhazardclasses(VHCs)andassociatedpotentialfuelloadmapsarepreparedfromacombinationofregionalecosystemmaps,foliageprojectcovermaps,landusemaps,waterbodymapsandtreeplantationmaps(foradditionalinformation,refertosection6).

VHCsaredescribedaccordingtoabinomialcodingsystem,acombinationofthevegetationcommunity’sbroadvegetationgroup(BVG)classification(1:2million)andthestructuralcharacteristicsofthevegetation(Figure6).

ThefirstpartoftheVHCcodereferstothe35broadvegetationgroups(1:2million)inQueensland,accordingtoNeldneretal.(2015)33,withanadditionaleightcategoriesrepresentingbuilt-upareassuchasurbancentresandtowns,developedruralareas,cultivatedareas(intensiveandbroadacreagricultureandplantations)andwaterbodies.Thesecondpartofthecodedescribessixvegetationstructureclasses(referFigure16)rangingfrommid-densetreestoshrubstonilvegetation.

Whereapatchorcorridorofcontinuoustree-orshrub-dominatedvegetationissurroundedbyacontinuousfueltype(suchasunmanagedgrassland,horticultureorcroppingareas),firesthatenterthatpatchoftreesorshrubsfromtheadjacentgrasslandcanquicklyachieveafirelineintensitycomparabletolargerpatchesofcontinuoustreeorshrubvegetation.

Ontheotherhand,whereapatchorcorridorofhazardoustree-orshrub-dominatedvegetationissurroundedbydiscontinuousfuel(suchasgrasslandunder10centimetersorlow-hazardareassuchasdenselybuilt-upareasorwater),alargerpatchsizeandwidthofvegetationisrequiredbeforeafirewouldreachsufficientintensitytoposeasignificantthreattolifeorproperty(i.e.firelineintensitygreaterthan4,000kW/m).

Detailsoffuelcontinuityofvegetationhazardclasses,lifeform,height,andrelativedensityofvegetationstructuralclassesareprovidedinFigures12to16insection6.

4.2.2 Creation of slope maps

Landscapescaleslopemapsarecreatedfroma25metreresolutiondigitalterrainmodelbycalculatingthemaximumslope(indegrees)fromthecentralpixelinagroupof9x9cellstotheeightadjoiningcellsinthatgroup.

4.2.3 Creation of potential fire weather maps

Apotentialseverefireweathermapiscreatedbyafour-stageprocess:

1. DevelopagriddedpredictionofFFDIforQueensland,onan83kilometregridandatthree-hourlyintervals,overtheperiodfrom1979to201134fromtemperature,wind,relativehumidityandprecipitationweatherproductsproducedbyBoM.

2. Incorporatefutureclimatetrendsto2050byadjustingtemperatureandrelativehumidityusingtheIntergovernmentalPanelonClimateChangeA1FIclimatescenario.35

3. Calculatethe5%AEP(i.e.5%chanceofoccurringinanygivenyear)FFDIbasedonastatisticaldistributionofFFDIforeachcelloftheadjustedBoMweathergrid.

4. Resamplethe83kilometreBoMgridto25metreandtomodifynear-coastalFFDIestimatestoaccountforanunderestimationofFFDIinBoMgridcellsthatspanbothland and ocean.

4.2.4 Creation of potential fireline intensity maps

Thethreeinputs–potentialfuelload,potentialseverefireweatherandmaximumslope–arecombinedusingequation1belowtocalculatepotentialfirelineintensity(PFI).

Equation1.Calculationofpotentialfirelineintensity:

PFI = 0.62 PFL2FFDIexp(0.069Slope)

Where:

PFI=potentialfirelineintensity(kW/m)

PFL=potentialfuelload(tonnes/ha)

FFDI=potentialseverefireweather(FFDI)

Slope=maxslope(+20<slope<-15,degrees)

4.2.5 Creation of potential bushfire intensity and potential impact buffer maps

Potentialbushfireintensitymapsaregeneratedbyclassifyingthepotentialfirelineintensityforinclusioninthebushfireproneareaas4,000+kW/m,withanadditionalpotentialimpactbufferof100linearmetreswidthdelineatedaroundtheextentofhazardousvegetationidentifiedasbushfireprone.Thepotentialimpactbufferformspartofthebushfirepronearea.

4. Process for preparation and review of statewide SPP IMS bushfire prone area mapping

22. 1•Broadvegetationgroup(1:2m)

•VegetationStructureClass

33 Neldner, VJ, and Niehus et al. (2015), The vegetation of Queensland: Descriptions of broad vegetation groups. 34 This year range maybe extended to the present year depending on available datasets from the BoM.35 This report and additional information regarding more recent climate scenarios can be found at https://www.ipcc.ch/report/emissions-scenarios/ accessed August 2019.

Figure6

https://www.ipcc.ch/report/emissions-scenarios/

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4.2.6 Modify potential intensity of small patches and corridors

TheSPPIMSbushfireproneareamappinglayerhasbeenfurtherrefinedinsomeregionsofQueensland.Thisprocessinvolvesapplyingthefollowingpatchandcorridormappingrulestoreflectthelikelihoodoflowerfirelineintensitiesinsmallervegetationpatchesandvegetationcorridors.

Step 1

Removesub-hectareareasofcontinuousfuel(i.e.surroundedbyeithernofuelornon-continuousfuel)thatarefurtherthan100metresfromanyothercontinuousfuelgreaterthan

twohectares.Theseareasarenotlikelytoigniteduetotheirdisconnectionwithfuelsthatcancarryrunningfirefronts.Ifignitedtheyaremostlikelytobecausedbypointignitionsthatrequirebothdistanceandareatodevelopintoafirefrontofconsiderablehazard.

Ifafirefrontemergesfromaonehectarepatch,itislikelytobenarrowandsignificantlylessintensethanafirefrontthathashadsufficienttimeandareatodevelop.Thecombinationoftheselikelihoodandintensityestimatesdeemittobeequivalenttoalessthan4,000kW/mfirelineintensityand,accordingly,areconsideredaslowhazardforthepurposeoflanduseplanninganddevelopmentassessment.

Step 2

Downgradetheeffectivefuelloadofcontinuousvegetationpatchesmeasuring(a)1to2hectares(by66percent),and(b)2-3hectarepatches(by50percent)ifthepatchissurroundedbyeithernon-continuousfueloralow-hazardvegetationorlandusetype,andifthepatchisfurtherthan100metresfromanyothercontinuous-fuelvegetationpatchgreaterthantwohectares.

Patchesofthissize(<3hectares)andproximitytolargerpatchesofcontinuousvegetationarelesslikelytoigniteduetotheirdisconnectionwithvegetationthatcancarryrunningfire

fronts.Ifignited,thesepatchesaremostlikelytobeignitedbypointignitionsthatrequirebothdistanceandsizetodevelopintoasignificantfirefrontofhighintensity.

Ifafirefrontemergesfromthesepatches,itislikelytobenarrowandofsignificantlylowerintensitythanafirefrontthathashadsufficienttimeandsizetodevelop.Thecombinedeffectofbothlowerignitionlikelihoodandlowerfirelineintensityislikelytoresultinafirelineintensitythatissignificantlylessthanlargerareasofcontinuousvegetation.

(a)Exampleofvegetationpatchesof<1hasurroundedby discontinuous-fuellandcoverandvegetationpatch>1ha

(b)ResultingBushfireProneAreamappingittustratingremoval ofsmallisolatedvegetationpatches<1ha

Figure7:Characteristicsofappropriatesub-hectarearearemoval.Source:Leonardetal2017.

PATCH SIZE APPROX. PATCH DIMENSIONS ASSUMED DECREASE OF FIRE-LINE INTENSITY

(a)0.5–2hectares 100mx100m–100mx200m 66%

(b)2–3hectares 100mx200m–150mx200m 50%

21

(a)Greaterthan2hectarespatchpriortofuelloaddowngrade (b)Lessthan2hectarespatchafterfuelloaddowngrade

Figure8:Characteristicsofeffectivefuelloaddowngradesforsmallpatches.Source:Leonardetal2017.

(a)Patchbetween2to3hapriortofuelloaddowngrade (b)Patchbetween2to3haafterfuelloaddowngrade

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Step 3

Removenarrowcorridorsandareasofcontinuousfuel<50metresinwidththatarenotsufficientlywidetosupportafullydevelopedflamefront.Theseareasarelesslikelytoigniteduetotheirdisconnectionwithfuelsthatcancarryrunningfirefronts.Ifignitedbyapointorlineignition,theseareaswill

limitthefireheadwidthand,asaresult,thefirelineintensity.Thecombinedeffectoflowerignitionlikelihoodandlowerintensityislikelytoresultinfirelineintensityoflessthan4,000kW/m,andthispresentsalowhazardtolanduseplanninganddevelopmentassessment.

Step 4

Smallfragmentsareremovedbecauseofthevariedqualityofthevegetationmappinginputs.Onlypatchesoftreeorshrubdominatedvegetationgreaterthan0.5hectaresareconsistentlyobservedwithhighconfidence.Smallerpatchesareoftenobservedtocontainmixturesofdifferentlandusesorcontinuousanddiscontinuousvegetation.Asaconsequence,isolatedpatchesofhazardousvegetationlessthan0.5hectares

insizearenotlikelytogenerateafirelineintensityof4,000kW/morprovidehighexposuretobuiltassets.

Therefore,isolatedpatchesoflessthan0.5hectares,ofveryhigh,highormediumpotentialbushfirehazardaredowngradedtolowhazard.Anypatchlessthan0.5hectaresofthesameclassisdowngradedtolowhazard(nolongerbushfirepronearea).

(a)Continuousfuel50matnarrowestpartofcorridor (b)Narrowcorridor<75mhasbeenremoved

Figure9:Characteristicsoftheeffectiveremovalofnarrowcorridorslessthan50m.Source:Leonardetal2017.

(a)Hazardousvegetationpatches<0.5ha (b)Patchesofhazardousvegetation<0.5haremoved

Figure10:Characteristicsofeffectiveremovalofsmallfragments<0.5ha.Source:Leonardetal2017.

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4.3 Methodology for local government review of SPP IMS bushfire prone area mapping

AlocalgovernmentmayseektolocallyrefinetheSPPIMSbushfireproneareamappingbyfollowingthesestepsandprocesses.

4.3.1 Undertake reliability assessment

Estimatethereliabilityofmapsproducedusingthismethodology.Thestepsare:

Step 1 – Select representative ‘cells of interest’

Decideonanadequatenumberofrepresentative1kilometrex1kilometre‘cellsofinterest’tocovertherangeoflandscapesandlandusesinthelocalgovernmentarea,whileconsideringfuturedevelopmentpriorities,thediversityoflandforms,vegetationtypesandotherfactorsaffectingtheriskofbushfirestopeopleandproperty.Theminimumnumberof‘cellsofinterest’is45,butcanbeincreasedto120fordiverselocalgovernmentareas.Theserepresentative‘cellsofinterest’shouldincludeoneorbothofthesetwosamplesets:

• sampleset(a):randomlyselectedcellstoconfirmthereliabilityofmappingacrossthelocalgovernmentarea

• sampleset(b):subjectivelyselected(non-random)cellsinknownareasofpoorreliabilityforinitialoriterativerefinementofthemapping.

Alllocalgovernmentswillneedtocompletesampleset(a)toconfirmthereliabilityofbushfireproneareamapping,whereasset(b)isonlyrequiredwherethelocalgovernmentisseekingtoimprovemappinginconjunctionwithQueenslandFireandEmergencyServices(QFES).

The‘cellsofinterest’shouldspanallbushfireproneareacategories–veryhighpotentialbushfireintensity,highpotentialbushfireintensity,mediumpotentialbushfireintensityandpotentialimpactbuffer.

Step 2 – Assess and record the reliability of the bushfire prone area and VHC mapping

Withineach1kilometrex1kilometre‘cellofinterest’,undertakeadesktopassessmentofthereliabilityofbushfireproneareaandVHCmappingforeachofthefour200metrediametercircularassessmentareas.Anexpertwithexperienceinbushfiremanagementandvegetationmanagementshouldestimatethereliabilityofthemappingbyreferringtorecentaerialphotography,othermappingsourcesandlocalknowledge.

ReferencetotherelevantversionoftheQueenslandHerbarium’sregionalecosystemmappingisparticularlyuseful.Theassessmentshouldalsoaddressthebushfireproneareamappingmethodology,relevantinputdatasets(e.g.potentialfireweatherseverity,maximumlandscapeslope)andtheapplicationofthisinformationforlanduseplanning,bushfiremitigationplanningorriskassessment.

Thereliabilityofeachcircularassessmentareashouldberecordedaseither:

• Satisfactory(S):

> mappedboundariescoincidewiththeextent ofvegetationorlanduseboundariesevidentonaerial photography;differencesareusuallywithin25metres andoccasionallywithin50metres,and

> mappedhazardclassesprovideacloseapproximation ofthepotentialbushfireintensityclasses.

or

• Notsatisfactory(N)

> mappedboundariesarequitedifferentfromcurrent vegetationandlanduseboundaries;differencesare often50metresormore,and

> mappedclassesprovideapoorapproximationof potentialbushfireintensityclasses,or

> mappingfailstoadequatelyidentifysignificant areasofhazardousvegetation,whereeitherpotentially hazardousvegetation(potentialbushfireintensity classes)isnotmapped(omission)ormappingindicates thepresenceofpotentiallyhazardousvegetationthatis absent(commission).

Step 3 – Tally reliability results

Resultsofthereliabilityassessmentshouldbesummarisedforallareasofinterestbycalculatingthenumberandpercentageofcircularassessmentareasestimatedassatisfactory(S)ornotsatisfactory(N)fortherandomlyselectedcells.

Step 4 – Consider suitability of mapping

Areportofbushfireproneareamappingshouldbepreparedtosummariseresultsofthereliabilityassessmentandthesuitabilityofmapsforplanningpurposes.Ingeneral,areliabilityof90percentorgreaterforbushfireproneareamapsisconsideredsuitableforthepreparationoflocalgovernmentplanningschemesandotherstrategicplanningdecisions.

4.3.2 Locally refine mapping

Wheremappingisnotofsufficientreliability,localgovernmentsmayseektoeither:

• liaisewithQFEStoconfirmandresolveidentifiedmappingissuesinstatewidebushfirehazardareamaps,or

• preparelocalscalebushfirehazardareamapsusingimprovedlocalvegetationorslopemappingapplyingthesamemethodologyasthestateusedinpreparingthe SPPIMSbushfireproneareamapping,asdescribedinsection4.2.

5. PROCESS FOR UNDERTAKING A BUSHFIRE HAZARD ASSESSMENT

24


25

5. Process for undertaking a Bushfire Hazard Assessment

5.1 Introduction

Thissectionisapplicablewherealocalgovernment’splanningschemecontainsprovisionsthatenableorrequireanapplicanttoundertakeaBushfireHazardAssessment(BHA)toreviewtheapplicablebushfireproneareamappingforanindividualassessmentarea.

Theapplicantisthenabletodeterminetheextentofbushfireproneareasandlevelofrisktowhichasiteisexposed,includingassessmentofspatialfactorsthatcontributetobushfirehazard.Inturn,thisenablesanapplicanttoproposealternativeassetprotectionzonewidthstotheacceptablelevelscontainedintheplanningscheme.

Localgovernmentsmayprovidethisoptiontoapplicantswhentheybelievesthereismeritinallowinganapplicantto:

• verifytheprecision,accuracyorcurrencyofthemapofbushfireproneareasormapinputdatasets(refertosection2forfurtherexplanationofwhythisisoftenjustifiable),or

• modifyanyoftheinputvariablesappliedincreatingtheplanningschememappingtoreflectchangesthatmayhaveoccurredovertime,suchasvegetationhazardclass.

Inaddition,aBHAmayberequiredbyalocalgovernmentaspartofadevelopmentproposalthatinvolvesareasdesignatedforrevegetationandrehabilitation,toensurethiswillnotcreateanew/expandedareathatwouldmeetthecriteriaofbecomingabushfireproneareaifassessedinaccordancewiththemethodologyusedtogeneratetheStatePlanningPolicyInteractiveMappingSystem(SPPIMS)mapping.

ConclusionsofadetailedBHAaretypicallypresentedasabushfirehazardreportoraspartofaBushfireManagementPlan(BMP).Refertosection8.3fordetailstobeincludedinabushfirehazardreportorBMP.

AlocalgovernmentmaywishtoeitherreferapplicantstothistechnicalguidancedocumentorprovideinformationaboutundertakingaBHAandpreparingabushfirehazardreportorBMPinitsplanningscheme(forexampleasaplanningschemepolicy).

5.2 Overview: the three stages of a BHA

TheBHAprocessconsistsofthreestages:

1. Reliabilityassessment:ThepurposeofthereliabilityassessmentstageistoverifythereliabilityofexistingbushfireproneareamappingandstreamlinethedetailedBHAprocess.

2. Hazardassessment:Thereliabilityassessmentstagedeterminestheextentofbushfireproneareasandlevelofrisktowhichasiteisexposed,includinganassessmentofspatialfactorsthatcontributetobushfirehazard.Wheretheoutcomesofthereliabilityassessmentsuggestthattheprecisionand/oraccuracyofthebushfireproneareamapormapinputdatasetsareinsufficientoranapplicantseekstomodifyinputdata,ahazardassessmentinvolvingfieldinvestigationsorgroundtruthingmayberequired.Thiswouldincludetheprovisionofsufficientevidencetosupportachangetobushfireproneareainputdataandremapping,orclassificationoftheextentofbushfireproneareasandpotentialimpactbufferforthepurposesofthedevelopmentapplication.

3. Separationandradiantheatexposure:Usingthesitespecificassessmentoffactors,thisstagecomprisescalculatingtheassetprotectionzonewidthneededtoachievetheradiantheatfluxlimitsidentifiedintheplanningscheme,usingtheBushfireassetprotectionzonewidthcalculatoroutlinedinsection7.

Figure11belowprovidesanoverviewoftheBHAprocess.

Figure11:AnoverviewoftheBushfireHazardAssessment(BHA)process.

1. Reliability assessment

2. Hazard assessment

3. Separation and radiant Heat

Verifythe reliabilityof:

• Map of bushfire-proneareas

• Mappinginputs.

Calculation of separation distanceand radiantheatflux.

Assessmentofspatialfactors:• fireweather severity/FFDI(5%AEPfireweatherevent)

• VegetationHazardClass(VHC)

• slopeincludingeffectivefireslopeandsiteslope.

Model potential firelineintensity:• site-specificmapof bushfire-proneareas.

TheBHAprocessadaptsthemethodusedtogeneratetheSPPIMSbushfireproneareamappingdescribedin‘AnewmethodologyforState-widemappingofbushfireproneareasinQueensland’.

Theprocessenablesapplicantstoeither:

• adopttheinputvaluesforFFDI(5%AEPfireweatherevent),vegetationhazardclasses(VHCs)andmaximumlandscapeslopefromtheSPPbushfireproneareamappingandproceedtocalculatefirelineintensityandradiantheatfluxlevels,or

• createalocalscalebushfireproneareamapbasedonfieldsurveys,mappingandmodellingofspatialfactorsthatcontributetopotentialfirelineintensity.

5.3 Stage 1 – Reliability assessment

5.3.1 Approach

Althoughstatewidebushfireproneareamappingisregularlyupdated,landuseandvegetationcover,keycontributorstobushfirehazard,aresubjecttochange,particularlyregardingtheextentofhazardousvegetation.

Accordingly,firststepoftheBHAistoundertakeareliabilityassessmenttodeterminewhetherthesite’sobservedcharacteristicsareconsistentwiththeinputsusedtocreatethemappingandthemappingoutputs.

26


Areliabilityassessmentisundertakenforthesiteandalllandwithin150metresoftheproposeddevelopment.

Whereexistingmappingofbushfireproneareainputdataisassessedassatisfactory,themapinputdatacansimplybeappliedtodetermineradiantheatfluxandassetprotectionzonewidthandthenusersproceeddirectlytoStage3-calculationofseparationandradiantheatexposure.

Wheretheprecisionand/oraccuracyofthebushfireproneareamapormapinputdatasetsareinsufficient,thereliabilityassessmentprovidesamechanismtoundertakeamoredetailedassessmenttoconfirmtheextentofbushfireproneareas.

5.3.2 Data sources

Whenundertakingareliabilityassessment,relevantdatasourcestobeconsultedinclude:

• bushfireproneareamappinginputs:

> inlocalgovernmentplanningschememapping,or

> iflocalgovernmentplanningschemesreferenceout totheSPPIMS,dataisavailableinrasterformat fromtheQueenslandGovernmentdataportalas ‘bushfirehazardarea–bushfire-pronearea–inputs– Queensland’

• recentaerialphotography

• localknowledge

• fieldobservations.

5.3.3 Procedure

Theprocedureforundertakingasitereliabilityassessmentinvolvesthreesteps:

1. Confirmtheextentofmappedbushfireproneareascorrelateswiththeextentofhazardousvegetation. Thisensurestheareasmappedasbushfireproneactuallycontainhazardousvegetation.Thisstepcanbeundertakenusingacombinationofrecentaerialphotography,otheravailablemappingandsiteobservations.

2. ConfirmtheclassificationofhazardousvegetationisconsistentwiththemappedVHC.Thisensurestheunderlyingvegetationhazardclassisconsistentwiththemappedhazardclass(e.g.areasmappedasVHC9actuallycontain‘moisttodryeucalyptclosedtoopenforestsusuallyoncoastallowlandsandranges’.

3. Confirmsiteandeffectiveslopesaregenerallyconsistentwiththemappedmaximumlandscapeslope.36Thisensurestheunderlyingslopesareconsistentwiththemappedmaximumlandscapeslope.Althoughslopeisunlikelytochangesubstantially,landscapeslopemaybeaffectedbydevelopmentandearthworksonadjoiningsites.Observedslopesthatarewithintwodegreesofthemappedmaximumlandscapeslopeareconsideredreliable(i.e.themaximumlandscapeslopecanbeusedasaninputtotheStatePlanningPolicyJuly2017(SPP)Bushfireassetprotectionzonewidthcalculator).

Assessorsshouldproceedtothehazardassessmentstagewheretheresultsofanystepindicatethaterrorsoromissionsinthemappingexist.

Wheretheresultsofthisprocedureindicatetheinputmappingisreliable,assessorscanusethemapinputdataandproceedtostage3tocalculateseparationandradiantheatexposureusingtheBushfireassetprotectionzonewidthcalculatoroutlinedinsection7.

5.4 Stage 2 – Hazard assessment

5.4.1 Approach

ThesecondstepoftheBHAinvolvestheidentification,groundtruthingandmappingofspatialfactorsthatcontributetopotentialfirelineintensityandproductionofasitespecificmapofbushfireproneareas.

Thehazardassessmentmustincludethedevelopmentfootprintandalllandwithin150metresofthedevelopmentfootprint.

Thehazardassessmentmayrequirethere-modellingofbushfirebehaviourandallowforpotentialre-mappingoftheextentofbushfireproneareas.Re-modellingwouldrequireaccesstoskillsinspatialanalysisandmodelling,includingtheuseofspecialistgeographicinformationsystem(GIS)software.

Example:

Thebushfireproneareamapindicatesthatpartofthesiteislocatedwithinthepotentialimpactbufferandwithin100metresofmappedareaswith a medium, high or very high potentialbushfireintensity.

Site inspection and comparison of aerialphotography taken over a period indicatesthat some of the nearby vegetation on landmapped with a medium, high or very highpotential bushfire intensity has been clearedand replaced with sparsely vegetated areasandbuilt-upareas.

A detailed assessment may be necessary todemonstrate changes in the level of hazardand/or the location of the potential impactbuffer.

The development area may require re-mapping of vegetation hazard classes andspatial modelling of bushfire prone areas,together with sufficient supporting evidence(e.g.timeseriesaerialphotography).

36 Available in raster format, from the Queensland Government data portal if mapping is referenced out to the statewide interactive mapping system.

https://data.qld.gov.au/

27

5.4.2 Procedure

Theprocedureforundertakingahazardassessmentinvolvesfoursteps:

1. Identify fire weather severity

IdentifyallFFDI(5%AEPfireweatherevent)valueswithintheassessmentarea.Datacanbeobtainedfromthebushfirehazardarea–bushfire-pronearea–inputs–Queensland,whichisavailableinrasterformatfromtheQueenslandGovernmentdata portal.

Note–Thesite-specificFFDI(5%AEPfireweatherevent)indexvalueistobeadoptedforhazardassessmentandmodellingpurposes.TheFFDIvalueof40,adoptedinmethod1ofAS3959–2009,shouldnotbeusedasitfailstoconsiderregionaldifferencesinweatherseveritythatmightbeexpectedforthe5%AEPfireweatherevent.TheadoptionoflocallyapplicableFFDI(5%AEPfireweatherevent)valuesdoesnotconflictwithAS3959–2018,whichexplicitlyallowsforrefinementofFFDIvalueswheresufficientclimatedataandmodellingisavailable(refertonotes,Table2.1,AS3959–2018).

2. Identify vegetation hazard class within the site assessment area from map of VHC

AlthoughthepotentialfuelloadsforaVHCcannotbemodified,analternativeVHCmaybeproposedwheretheresultsofareliabilityassessmentorsitespecificbotanicalsurveydemonstratedifferencesbetweentheobservedclassificationorextentofVHCsandthoseindicatedbythemappinginputsforvegetationhazardclasswhichisavailableinEsri®shapefile(.shp)format,fromtheQueenslandGovernmentdataportal(iflocalgovernmentplanningschememappingrefersouttothestatewideinteractivemappingsystem).

WherealternativeVHCsareproposed,fieldassessmentofvegetationcommunitiesmustbeundertakenaccordingtotheVHCassessmentmethodology.Fine-scaleassessmentofVHCsshouldbecarriedoutbyasuitablyqualifiedpersonwithexperienceinbotanicalsurveymethods.Fieldassessmentsmaybesupportedbyotherformsofevidenceincluding:

• airphotointerpretationusingcurrent,highresolutionaerialphotography

• QueenslandHerbariummappingofbroadvegetationgroups(BVGs)andregionalecosystems.

VHCsarethenidentifiedandmappedaccordingtotheproceduredescribedinsection6.TheoutputsoftheVHCassessmentaretoincludethefollowingmapsasspatialdata:

• Observedvegetationhazardclasses.

• Apostdevelopmentvegetationhazardclassmap,asaminimum,whichincorporatestheeffectsoftheproposeddevelopmentontheconfigurationofvegetationwithintheassessmentareaincludingallnecessaryclearingtosupportthedevelopmentandinfrastructureortomeetrequirementsforrevegetation,landscapingorenvironmentaloffsets.

Note–Developmentapprovalsonlandwithintheassessmentareacanmodifytheextentofhazardousvegetationwithinthelandscapeinwaysthatincreaseordecreasepotentialfuelloads:

> Intheshortterm,currentdevelopmentapprovalsthatpermitclearingbutarenotactedupon(inwholeorinpart)tendtomaintainorincreaselevelsofhazardwithinthelandscape.Assuch,wherethereislandwithinthesiteassessmentareainthiscircumstance,thevegetationistobemappedandclassifiedaccordingtoitscurrentextent.

> Conversely,whereareasofrevegetationareproposed,orcurrentdevelopmentapprovalsrequirerevegetationofclearedareastoachieveenvironmentaloutcomes,anincreasedhazardwithinthelandscape,notapparentduringtheinitialstagesofdevelopmentcanoccur.Wherethereislandwithinthesiteassessmentareainthiscircumstance,thevegetationistobemappedaccordingtotheapprovedrevegetationextentandthenclassifiedasthoughthevegetationhadreachedits‘remnantstate’,includingrulesforpatches

andcorridorsofvegetation.

• Potentialfuelloadsbasedonthepostdevelopmentdistributionofvegetationhazardclasseswithintheassessmentarea.

3. Identify site slope and effective slope from the mapping inputs for maximum landscape slope and determine whether the proposed lots or buildings are upslope or downslope of hazardous vegetation

Twoslopeinputparametersarerequiredfortheestimationoffirebehaviourandseparation:

1. Effectiveslope–themoreimportantofthetwo,referstotheslopeofthelandunderhazardousvegetationmeasuredindegrees.Effectiveslopehasadirectinfluenceonthepotentialrateoffirespreadandrateoffuelconsumption.

2. Siteslope–istheslopeofthegroundbetweentheedgeoftheproposeddevelopmentorsiteboundaryandtheedgeofhazardousvegetation.

Forsimpleassessmentstheeffectiveslopeisidentifiedaccordingtothefollowingprocedure:

• Determinetheslope(indegrees)ofalllandwithintheassessmentarea,includingtheslopeundereachVHC.WheremultiplecombinationsofslopesandVHCsexist,aconservativeapproachshouldbeadoptedtoensuretheriskofbushfireattack,particularlyflameattack,isadequatelyassessed.

• DeterminewhethertheVHCswithintheassessmentareawhichcontributetobushfirehazard(‘hazardousvegetation’)arelocatedupslopeordownslopeoftheproposeddevelopmentorlotboundaryinaccordancewithAS3959–2018:

> wheretheslopeofthelandcontaininghazardousvegetationisdownhillfromtheproposeddevelopmentorlotboundary,itisconsidered‘downslope’irrespectiveofthesiteslope

> wheretheslopeofthelandcontaininghazardousvegetationisuphillorisflat(i.e.0degrees)fromtheproposeddevelopmentorlotboundary,itisconsidered‘upslope’irrespectiveofthesiteslope.

Siteslopecanbedeterminedusingeitherthestatewidemapofmaximumlandscapeslope,localgovernmentdataorbasedonpostdevelopmentsiteslope,forexample,afterearthworksarecompleted.




28


Note–Topographicdatamaybeusedtocreateanalternativemapoflandscapeslopewithintheassessmentareasfrom:

> acontourmapavailablefromtheQueenslandSpatialCatalogue(or Qspatial)

> viasurveypreparedbyaSurveyorsBoardQueenslandregistered surveyor

> digitalterrainmodelorLiDARdataavailablefromtheQueensland SpatialCatalogue.

4. Prepare detailed mapping updates of potential bushfire intensity and potential impact buffer locations and intensity levels

WhereachangetothedistributionorclassificationofVHCswithintheassessmentareaisproposed,re-modellingofbushfirehazardmaybeundertakentodeterminehowthechangestoVHCs(andfuelloads)affectpotentialfirelineintensity.

Potentialfirelineintensityfortheassessmentareashouldbecalculatedinaccordancewiththemethoddescribedin‘AnewmethodologyforState-widemappingofbushfireproneareasinQueensland’.37

Thisupdatedsitespecificmapofbushfireproneareasandanyinputmapsproducedviathehazardassessmentmaythen‘replace’theSPPmaporplanningschememapforthepurposesofassessingtheapplication.

5.5 Stage 3 – Separation and radiant heat exposure

5.5.1 Approach

Radiantheatexposuremaybecalculatedusingeither:

1. TheBushfireassetprotectionzonewidthcalculator(preferred),or

2. Method2ofMethod2ofAS3959–2018,subjecttoadoptionof:

> SitespecificvaluesofFFDI(5%AEPfireweatherevent)determinedinaccordancewithprocedure5.4.2,Step1.

> Sitespecificvegetationhazardclassesandtheirassociatedpotentialfuelloadsdeterminedinaccordancewithprocedure5.4.2Step2,togetherwithmodifiedsurfacefuelloads(w)forcertainvegetationhazardclasses.

Forallforestandwoodlandvegetationhazardclasseswherefueliscontinuous,surfacefuelload(w)isthesumofsurfaceandnearsurfacefuelloadforthepurposesofcalculatingtherateofspreadinStep6ofMethod2inAS3959–2018.Figures13,14and16indicatefuelloadandstructuralclassesforforestandwoodlandVHCs.

> Effectivesiteslopesdeterminedinaccordancewiththeprocedurein5.4.2Step3.

Whereareliabilityassessmentwasundertakenandtheresultsofallstepsindicatetheinputmappingisreliable,assessorsshouldusethemappinginputdata(bydefault)asinputdataforthecalculationofradiantheatflux.WhereasitespecificBHAhasbeenundertaken,thedatafromsteps1to3insection5.4.2shouldbeusedforthecalculationofradiantheatflux.

5.5.2 Procedure for calculating

Theprocedureforcalculatingseparationandradiantheatexposureinvolvestwosteps:

1. Measure asset protection zone width between the development and hazardous vegetation

Theassetprotectionzoneshouldbemeasuredinaccordancewithclause2.2.4ofAS3959–2018foreachVHCandslopecombinationtowhichadevelopmentisexposed.

Theassetprotectionzoneisthehorizontaldistance(i.e.measuredinplan)betweentheedgeofhazardousvegetation(edgeofcanopyforforest,woodlandandheathtypeVHCs)andfor:

• subdivisions(reconfigurationofalotorRAL:theclosestpointonalotboundaryorabuildingenvelope(whereapplicable)

• materialchangeofuse:

> theclosestpointofabuildingenvelope,or

> theexternalwallofabuilding,or

> forpartsofthebuildingthatdonothaveexternalwalls(e.g.carports,decks,landingsetc.),thesupportingpostsorcolumns.38

Theedgeofhazardousvegetationshouldbedeterminedbyasitesurveyoftheedgeofthevegetationcanopy.Alternatively,aplanshowingtheedgeofthedevelopmentfootprintinrelationtohazardousvegetationmaybeused.

2. Calculate radiant heat exposure

TheBushfireassetprotectionzonewidthcalculatorenablesapplicantstodetermineradiantheatexposureorradiantheatflux(RHF,kW/m2)usingeithermappinginputdata(FFDI[5%AEPfireweatherevent],VHCandmaximumlandscapeslope)ortheinputdataobtainedviasteps1to3ofthehazardassessmentprocess:

• FFDI(5%AEPfireweatherevent)

• vegetationhazardclass

• siteslope(degrees),effectiveslope(degrees)andwhethertheeffectiveslopeisupslopeordownslopeofthedevelopment.39

Land,wheretheeffectiveorsiteslopeis‘flat’,shallhaveaminimumslopeof1degree.Usingavalueof1degreeisrequiredtosatisfythemathematicalformula,howeverithasnegligibleimpactonthecalculations.

Userscanadjusttheassetprotectionzonewidthtodeterminethedistancenecessarytoachievetheidentifiedacceptablelevelsofradiantheatflux.

FurtherinformationontheuseoftheBushfireassetprotectionzonewidthcalculatorisinsection7.

37 Leonard, J, Opie, K, et al. (2014), A new methodology for State-wide mapping of bushfire-prone areas in Queensland.

38 Drysdale, D (2011), An introduction to fire dynamics.39 Where adopting the SPP IMS mapping input data, refer to hazard assessment

step 3 in section 5.4.2 for determination of whether the effective slope is upslope or downslope of the development.

296. PROCESS FOR UNDERTAKING A VEGETATION

HAZARD CLASS ASSESSMENT

30


6. Process for undertaking a Vegetation Hazard Class Assessment

6.1 Introduction

Thissectionisapplicablewherealocalgovernment’splanningschemecontainsprovisionsthatenableorrequireanapplicanttoundertakeaBushfireHazardAssessment(BHA)toreviewtheapplicablebushfireproneareamappingforanindividualassessmentarea.

FuelloadsneedtobedeterminedwhenpreparingaBHA.AVegetationHazardClassAssessment–theprocessforidentifying,classifyingandmappingvegetationhazardclasses(VHCs)basedonbotanicalsurveyofvegetationcommunitieswithinanassessmentarea–canidentifythesepotentialfuelloads.

AlocalgovernmentmaywishtoreferapplicantstothistechnicalguidancedocumentorprovideinformationaboutundertakingaVHCassessmentinitsplanningscheme(forexampleasaplanningschemepolicy).

6.2 Process

TheprocessforidentifyingandclassifyingVHCsinvolvesabotanicalsurveyofthesiteandalllandwithinthesiteassessmentarea(150metresaroundthesite)accordingtothefollowingprocedure:

1. DeterminethelifeformoftheecologicallydominantlayeraccordingtolifeformcategoriesinFigure15.

Theecologicallydominantlayeristhestructurallayerwhichcontainsthegreatestamountofabovegroundbiomassand,becauseofitsphysiognomyandrelativecontinuity,dominatestherestofthecommunityinthesensethatitconditionsthehabitatsofotherstrata.40,41

Althoughavisualestimationisgenerallysufficienttoidentifytheecologicallydominantlayer,itmaybenecessarytomeasuretheheight,densityandcoverofeachlayerandtocalculatethelayer’sapproximatebiomassvolume.42Asanexample,treesarelikelytobetheecologicallydominantlayerwithinopenforestandwoodlandecosystems.

2. DetermineanddocumenttheaverageheightoftheecologicallydominantlayeraccordingtoheightclassesinFigure15(e.g.trees10-30metres).

3. EstimateanddocumenttherelativedensityoftheecologicallydominantlayeraccordingtoFigure15(e.g.closed-mid-dense).

4. Determinevegetationstructuralclassviathecombinationoflifeform,heightandrelativedensityaccordingtoFigure15(e.g.treesclosed–mid-dense=vegetationstructuralclass1).

5. DeterminethedominantplantspeciesintheecologicallydominantlayeranddeterminetheBroadVegetationGroups(BVGs)43fromVegetationofQueensland:DescriptionsofBroadVegetationGroups.44

TheidentificationofBVGsforremnantvegetationcanalsobedeterminedviagroundtruthingofcurrentregionalecosystemsonasiteaccordingtoMethodology for Survey and Mapping of Regional Ecosystems and Vegetation Communities in Queensland.45

Note–Vegetationcommunitiesarerarelyhomogeneous.Insomecases,itmaynotbepossible,norusefulfromamodellingperspective,tomapeachindividualvegetationcommunityseparatelywithintheassessmentarea,particularlyatscaleslessthan1:10,000.TheminimumpatchsizefordiscreteVHCsis1hectare.Incircumstanceswherethevegetationhazardclassisfoundtobeheterogeneous,thepotentialfuelloadisthesumoftheproportionsofthepotentialfuelloadforeachobservedVHC.TherelativeproportionofeachVHCwillneedtobedeterminedandthetotalpotential

fuelloadcalculatedaccordingtothesumoftheproportions:

Where:

=thesumofproportionsofpotentialfuelloadofnVHCs

pi=thepercentageoftheVHCcomprisedofthei thvegetationcommunity(VHC)

wi = the potential fuel load of the i thvegetationcommunity(VHC)intonnes

per hectare.

Thesameformulashouldbeusedwhethercalculatingtotalorsurfacefuelcomponents.Inthiscase,w

iisthepotentialsurfacefuelloadofthe

i thvegetationcommunity(VHC)intonnesperhectareandisthesumofsurfacefuelandnearsurfacefuelcomponentsfortheVHC.

6. DeterminetheVHCviathecombinationofBVG(1:2million)andvegetationstructuralclassaccordingtoFigure6onpagex.Figure6providesanexampleofthecombinationofBVGandvegetationstructuralclasstocreatethevegetationhazardclasscode.

7. CreateamapofobservedVHCs.

8. Developapost-developmentVHCmap.

Thisshouldincorporatetheeffectsoftheproposeddevelopmentontheconfigurationofvegetationwithintheassessmentareaincludingnecessaryclearingtosupportthedevelopmentortomeetrequirementsforrevegetation,landscapingorenvironmentaloffsets.Patchorcorridorfilteringrulesdescribedinsection4.2.6shouldbeappliedtothefinaldetailedmapofvegetationhazardclassestoproduceafinalmapofpostdevelopmentVHCs.

9. Derivepotentialfuelloadsbasedonthepostdevelopmentdistributionofvegetationhazardclasses,andcorrespondingfuelloadsfromFigure14.

WhereradiantheatexposureisproposedtobeassessedaccordingtoMethod2ofAS3959-2018,modifiedsurfacefuelloads(w)applyforcertainVHCs.Forallforestandwoodlandvegetationhazardclasses,calculatethesurfacefuelload(w)asthesumofsurfaceandnear-surfacefuelloadinFigure14.

10. AssignaVHCtobuilt-upareassuchasurbancentresandtowns,developedruralareasandcultivatedareas(intensiveandbroadacreagricultureandplantations).VHCsforbuilt-upareas,ruralareas,plantations,croppingandhorticultureandwaterbodies,aredeterminedviathecombinationofVHCfrom36–43listedinthe‘Vegetationhazardclass’columninFigure14andthecorrespondingvegetationstructureclassbyfollowingsteps1to4above.

40 Beadle, NCW and Costin, AB (1952), Ecological classification and nomenclature.41 Neldner, VJ (1984), South Central Queensland – Vegetation Survey of Queensland.42 Neldner, VJ, Wilson, BA, et al. (2012), Methodology for survey and mapping of

regional ecosystems and vegetation communities in Queensland Version 3.2. 43 Broad vegetation groups are a high-level grouping of vegetation communities

and are based on floristics, structural, functional, biogeographical and landscape attributes.

44 Neldner, VJ, Niehus, RE, et al. (2015), The vegetation of Queensland: Descriptions of broad vegetation groups. Version 2.0.

45 Neldner, VJ, Wilson, BA, et al. (2012), Methodology for survey and mapping of regional ecosystems and vegetation communities in Queensland Version 3.2.

31

Figure12belowshowsanexampleofthedifferencebetweenthepublishedmapofVHCandaverifiedmapofobservedVHCspreparedaccordingtotheVHCAssessmentprocedure.

Figure13indicatesthedifferencesinfuelloadsforthesameassessmentareabasedonthechangestotheVHCs.

Figure12:Statewidemapofvegetationhazardclass(VHC)(left)andexampleofagroundtruthedmapofobservedVHCs(right).87Source:Leonardetal2017.

Figure13:Fuelloadbasedonpublishedmapofvegetationhazardclass(VHC)(left)andexampleofafuelloadrasterbasedonobservedVHCs(right).Source:Leonardetal2017.

32


Vegetation hazard class descriptions and 80th percentile potential fuel load

Vegetation hazard class

Potentialfuelload(t/ha) Prone type46

Fuel continuity47

Surf

ace

Near-surface

Elevated

Bark

Total(Remnant)

Total(Non-remnant)

Remnant

Non-remnant

Remnant

Non-remnant

1.1 Complexmesophylltonotophyllvineforests 2.6 0.0 0.0 0.0 2.6 12.0 3 1 2 1

2.1 Complextosimple,semi-deciduousmesophylltonotophyllvineforest 3.5 0.0 0.0 0.0 3.5 12.0 3 1 2 1

3.1 Notophyllvineforest 4.5 0.0 0.0 0.0 4.5 12.0 3 1 2 1

3.3 Notophyllvinethicket 4.4 0.0 0.0 0.0 4.4 12.0 3 1 2 1

4.1 Notophyllandnotophyllpalmorvineforest 4.5 0.0 0.0 0.0 4.5 12.0 3 1 2 1

5.1 Notophylltomicrophyllvineforests 3.9 0.0 0.0 0.0 3.9 12.0 3 1 2 1

5.2 Notophylltomicrophyllvineforestwithsparseoverstorey 3.9 0.0 0.0 0.0 3.9 12.0 3 1 2 1

5.5 Sedgelandwithinnotophylltomicrophyllvineforests 3.9 0.0 0.0 0.0 3.9 12.0 3 1 2 1

6.1 MontaneNotophyllvineforestandmicrophyllfernforest 3.9 0.0 0.0 0.0 3.9 12.0 3 1 2 1

6.3 MontaneNotophyllvinethicketandmicrophyllfernthicket 3.9 0.0 0.0 0.0 3.9 12.0 3 1 2 1

7.1 Semi-evergreentodeciduousmicrophyllvineforest 6.0 0.0 0.0 0.0 6.0 12.0 3 1 2 1

7.2 Sparsesemi-evergreentodeciduousmicrophyllvineforest 6.0 0.0 0.0 0.0 6.0 12.0 3 1 2 1

8.1 Weteucalypttallopenforest 28.0 3.0 2.0 2.0 35.0 35.0 1 1 1 1

8.2 Weteucalypttallwoodland 18.0 3.1 1.7 1.0 23.8 23.8 1 1 1 1

9.1 Moisttodryeucalyptopenforestsoncoastallowlandsandranges 17.5 3.5 2.2 1.0 24.2 24.2 1 1 1 1

9.2 Moisttodryeucalyptwoodlandoncoastallowlandsandranges 11.4 3.5 1.3 1.0 17.2 17.2 1 1 1 1

9.3 Shrublandwithinmoisttodryeucalyptoncoastallowlandsandranges 7.8 3.0 1.9 0.0 12.7 12.7 1 1 1 1

10.1 Spottedgumdominatedopenforests 16.3 3.0 1.5 0.0 20.8 20.8 1 1 1 1

10.2 Spottedgumdominatedwoodlands 14.0 3.0 1.0 0.0 18.0 18.0 1 1 1 1

11.2 Moisttodryeucalyptwoodlandsonbasaltareas 7.5 4.0 0.5 1.0 13.0 13.0 1 1 1 1

12.1 Dryeucalyptopenforestonsandstoneandshallowsoils 15.0 3.5 1.5 1.0 21.0 21.0 1 1 1 1

12.2 Dryeucalyptwoodlandsonsandstoneandshallowsoils 12.0 2.6 1.8 1.0 17.4 17.4 1 1 1 1

13.1 Drytomoisteucalyptopenforestsonundulatingmetamorphicsandgranite 15.9 3.5 1.4 1.0 21.8 21.8 1 1 1 1

13.2 Drytomoisteucalyptwoodlandsonundulatingmetamorphicsandgranite 9.4 3.4 0.6 1.0 14.4 14.4 1 1 1 1

46 Prone type: 1 = Bushfire prone, 2 = Grass fire prone, 3 = Low hazard 47 Fuel continuity: 1 = Continuous, 2 = Discontinuous

33




Fuel continuity47

Surf

ace

Near-surface

Elevated

Bark

Total(Remnant)

Total(Non-remnant)

Remnant

Non-remnant

Remnant

Non-remnant

13.3 Shrublandassociatedwithdrytomoisteucalyptwoodlandsonundulatingterrain

4.3 2.3 0.9 0.0 7.5 7.5 1 1 1 1

14.1 OpenforestdominatedbyDarwinstringybark,MelvilleIslandbloodwoodorscarletgum

22.3 1.4 2.1 2.0 27.8 27.8 1 1 1 1

14.2 WoodlandsdominatedbyDarwinstringybark,MelvilleIslandbloodwoodorscarletgum

8.4 2.4 0.8 1.0 12.6 12.6 1 1 1 1

14.3 ShrublandassociatedwithwoodlandsdominatedbyDarwinstringybark,MelvilleIslandbloodwoodorscarletgum

1.1 3.4 3.3 1.0 8.8 8.8 1 1 1 1

14.6 SparselyvegetatedareasassociatedwithDarwinstringybark,MelvilleIslandbloodwoodorscarletgum

0.0 0.3 1.3 0.0 1.6 1.6 3 3 2 2

15.1 Temperateopeneucalyptforests 23.7 0.3 1.8 1.0 26.8 26.8 1 1 1 1

15.2 Temperateeucalyptwoodlands 10.2 1.8 1.8 0.0 13.8 13.8 1 1 1 1

16.1 Eucalyptusdominatedforestondrainagelinesandalluvialplains 10.0 3.8 1.2 1.0 16.0 16.0 1 1 1 1

16.2 Eucalyptusdominatedwoodlandondrainagelinesandalluvialplains 7.5 3.6 0.5 0.0 11.6 11.6 1 1 1 1

16.3 Shrublandassociatedwitheucalyptuswoodlandsondrainagelines 5.8 2.7 0.1 0.0 8.6 8.6 1 1 1 1

16.4 Grasslandassociatedwitheucalyptusdominatedwoodlandsondrainagelines

0.3 2.1 0.1 0.0 2.5 2.5 2 2 1 1

16.5 Sedgelandassociatedwitheucalyptuswoodlandsondrainagelines* 3.9 5.0 3.5 0.0 12.4 12.4 1 1 1 1

16.6 Sparselyvegetatedareasassociatedwitheucalyptuswoodlandsondrainagelines

1.2 2.0 0.0 0.0 3.2 3.2 3 3 2 2

17.1 Dryopenforestsdominatedbypoplarbox,silver-leavedironbarkorWhite'sironbarkonsandordepositionalplains

10.6 4.1 0.3 0.0 15.0 15.0 1 1 1 1

17.2 Drywoodlandsdominatedbypoplarbox,silver-leavedironbarkorWhite'sironbarkonsandordepositionalplains

6.0 3.0 0.6 0.0 9.6 9.6 1 1 1 1

18.1 Dryeucalyptusopenforestsonsandordepositionalplains 10.8 3.4 0.6 0.0 14.8 14.8 1 1 1 1

18.2 Dryeucalyptuswoodlandsonsandordepositionalplains 7.1 3.3 0.6 0.0 11.0 11.0 1 1 1 1

18.5 Sedgelandassociatedwithdryeucalyptwoodlandsonsandordepositionalplains

3.9 3.4 3.5 0.0 10.8 10.8 1 1 1 1

19.2 Lowopeneucalyptuswoodlandsdominatedbysnappygum,CloncurryBoxorNormantonbox

4.3 3.0 0.8 1.0 9.1 9.1 1 1 1 1

19.3 Shrublandassociatedwithlowopeneucalyptwoodlandsdominatedby snappygum,CloncurryBoxorNormantonbox

1.7 1.5 1.3 0.0 4.5 4.5 1 1 1 1

19.4 Grasslandassociatedwithlowopeneucalyptwoodlandsdominatedby snappygum,CloncurryBoxorNormantonbox

1.6 3.3 0.3 0.0 5.2 5.2 2 2 1 1

20.1 Openforestsdominatedbywhitecypresspineorcoastcypresspine 12.5 2.4 0.6 1.0 16.4 16.5 1 1 1 1

34





Fuel continuity47

Surf

ace

Near-surface

Elevated

Bark

Total(Remnant)

Total(Non-remnant)

Remnant

Non-remnant

Remnant

Non-remnant

20.2 Woodlandsdominatedbywhitecypresspineorcoastcypresspine 5.4 3.1 0.8 0.0 9.3 9.3 1 1 1 1

21.1 Melaleucadryopenforestonsandplainsordepositionalplains 7.8 3.7 1.4 2.0 14.9 14.9 1 1 1 1

21.2 Melaleucadrywoodlandsonsandplainsordepositionalplains 3.7 3.4 0.6 1.0 8.7 8.7 1 1 1 1

21.3 Shrublandassociatedwithmelaleucadrywoodlandsonsandplainsor depositionalplains

4.3 2.3 0.9 0.0 7.5 7.5 1 1 1 1

21.6 Sparselyvegetatedareasassociatedwithmelaleucadrywoodlandson sandplainsordepositionalplains

2.5 0.2 1.8 0.0 4.5 4.5 3 3 2 2

22.1 Melaleucaopenforestsonseasonallyinundatedlowlandcoastalswamps 15.4 8.0 3.0 2.0 28.4 28.4 1 1 1 1

22.2 Melaleucawoodlandsonseasonallyinundatedlowlandcoastalswamps 10.6 7.1 1.0 1.0 19.7 19.7 1 1 1 1

22.3 Shrublandassociatedwithmelaleucawoodlandsonseasonallyinundatedlowlandcoastalswamps

4.3 2.3 0.9 0.0 7.5 7.5 1 1 1 1

22.5 Sedgelandassociatedwithmelaleucawoodlandsonseasonallyinundatedlowlandcoastalswamps

6.0 5.0 1.8 1.0 13.8 13.8 3 1 2 1

23.2 Mulgadominatedwoodlandsonredearthplains,sandplainsorresiduals 1.2 3.6 0.2 0.0 5.0 5.0 1 1 1 1

23.3 Shrublandassociatedwithmulgaonredearthplains,sandplainsorresiduals. 1.4 3.2 0.1 0.0 4.7 4.7 1 1 1 1

23.4 Grasslandassociatedwithmulgaonredearthplains,sandplainsorresiduals 1.6 3.3 0.3 0.0 5.2 5.2 2 2 1 1

24.1 Acaciaopenforestonresiduals 6.9 2.6 0.6 0.0 10.1 10.1 1 1 1 1

24.2 Acaciawoodlandsonresiduals 4.5 2.8 0.9 0.0 8.2 8.2 1 1 1 1

24.3 Acaciashrublandsonresiduals 2.6 2.1 2.1 0.0 6.8 6.8 1 1 1 1

24.4 Grasslandcommunitiesassociatedwithacaciaonresiduals 1.6 3.3 0.3 0.0 5.2 5.2 2 2 1 1

24.6 Sparselyvegetatedareasassociatedwithacaciaonresiduals 0.3 3.6 0.0 0.0 3.9 3.9 3 3 2 2

25.1 Brigalowbelahopenforestsonheavyclaysoils 10.5 2.6 1.9 0.0 15.0 15.0 1 1 1 1

25.2 Brigalowbelahwoodlandsonheavyclaysoils 3.4 2.1 0.7 0.0 6.2 6.2 1 1 1 1

25.3 Shrublandcommunitiesassociatedwithbrigalowbelahonheavyclaysoils 2.0 1.4 0.4 0.0 3.8 3.8 1 1 1 1

26.1 Gidgeeblackwooddominatedopenforest 6.0 1.0 1.4 0.0 8.4 8.4 1 1 1 1

26.2 Gidgeeblackwoodwoodland 2.0 1.6 0.2 0.0 3.8 3.8 1 1 1 1

26.3 Shrublandcommunitiesassociatedwithgidgeeblackwoodwoodland 1.4 1.9 1.5 0.0 4.8 4.8 1 1 1 1

35




Fuel continuity47

Surf

ace

Near-surface

Elevated

Bark

Total(Remnant)

Total(Non-remnant)

Remnant

Non-remnant

Remnant

Non-remnant

27.1 Mixedspeciesopenforestsdominatedbywesternwhitewood,boreeorwoodeddowns

2.1 0.7 0.1 0.0 2.9 2.9 1 1 1 1

27.2 Mixedspecieswoodlandsdominatedbywesternwhitewood,boreeor woodeddowns

2.0 2.5 0.3 0.0 4.8 4.8 1 1 1 1

27.3 Shrublandcommunitiesassociatedwithmixedspecieswoodlands 1.0 0.9 0.1 0.0 2.0 2.0 1 1 1 1

27.4 Grasslandcommunitiesassociatedwithmixedspecieswoodlands 0.1 4.0 0.0 0.0 4.1 4.1 2 2 1 1

27.5 Sedgelandcommunitiesassociatedwithmixedspecieswoodlands 1.6 4.3 0.1 0.0 6.0 6.0 1 1 1 1

28.1 Openforestsincoastallocationswithspeciessuchasshe-oakorswampbox 22.2 2.7 2.0 0.0 26.9 26.9 1 1 1 1

28.2 Woodlandsincoastallocationswithspeciessuchasshe-oakorswampbox 13.8 3.2 1.3 0.0 18.3 18.3 1 1 1 1

28.3 Shrublandassociatedwithwoodlandsincoastallocation 12.2 2.2 2.5 0.0 16.9 16.9 1 1 1 1

28.4 Grasslandassociatedwithwoodlandsincoastallocations 8.0 2.4 2.0 0.0 12.4 12.4 1 1 1 1

28.5 Sedgelandassociatedwithwoodlandsincoastallocations 6.0 5.0 3.5 1.0 15.5 15.5 1 1 1 1

28.6 Sparselyvegetatedareasassociatedwithwoodlandsincoastallocations 1.0 1.0 1.3 0.0 3.6 3.6 3 3 2 2

29.1 Forestsassociatedwithheathlandsandscrubs 18.1 2.6 3.2 1.0 24.9 24.9 1 1 1 1

29.2 Woodlandsassociatedwithheathlands,scrubsandshrublands 12.0 4.8 7.5 0.0 24.3 24.3 1 1 1 1

29.3 Heathlandsandassociatedscrubsandshrublands 11.6 2.9 5.6 0.0 20.1 20.1 1 1 1 1

29.4 Grasslandcommunitiesassociatedwithheathlands,scrubsandshrublands 4.8 4.4 2.0 0.0 11.2 11.2 1 1 1 1

29.5 Sedgelandcommunitiesassociatedwithheathlands,scrubsandshrublands 3.0 5.0 3.5 0.0 11.5 11.5 1 1 1 1

29.6 Sparselyvegetatedareasassociatedwithheathlands,scrubsandshrublands 0.0 2.1 0.5 0.0 2.6 2.6 3 3 2 2

30.2 WoodlandsassociatedwithMitchellgrassorbluegrass 1.0 2.9 0.1 0.0 4.0 4.0 1 1 1 1

30.3 ShrublandsassociatedwithMitchellgrassorbluegrass 0.8 2.0 1.4 0.0 4.2 4.2 1 1 1 1

30.4 Mitchellgrassorbluegrasstussockgrasslands 0.8 4.0 0.0 0.0 4.8 4.8 2 2 1 1

30.5 SedgelandsassociatedwithMitchellgrassorbluegrass 1.6 4.3 0.1 0.0 6.0 6.0 1 1 1 1

31.2 Woodlandsassociatedwithinlandforblandstotussockgrasslands 1.0 3.0 0.7 0.0 4.7 4.7 1 1 1 1

31.3 Shrublandsassociatedwithinlandforblandstotussockgrasslands 0.8 2.0 1.4 0.0 4.2 4.2 1 1 1 1

31.4 Mixedopenforblandstotussockgrasslandsininlandlocations 0.6 2.1 0.1 0.0 2.8 2.8 2 2 1 1

31.5 Mixedopensedgelandsassociatedwithinlandtussockgrasslands 0.6 0.2 0.1 0.0 0.9 0.9 3 3 2 2

36





Fuel continuity47

Surf

ace

Near-surface

Elevated

Bark

Total(Remnant)

Total(Non-remnant)

Remnant

Non-remnant

Remnant

Non-remnant

32.2 Woodlandsassociatedwithcoastalclosedtussockgrasslands 2.4 4.4 0.0 0.0 6.8 6.8 1 1 1 1

32.3 Shrublandassociatedwithcoastalclosedtussockgrasslands 0.8 2.0 1.4 0.0 4.2 4.2 1 1 1 1

32.4 Closedtussockcoastalgrasslands 2.1 3.6 0.3 0.0 6.0 6.0 2 2 1 1

33.3 ShrublandsassociatedwithHummockgrasslands 0.8 2.0 1.4 0.0 4.2 4.2 1 1 1 1

33.4 Hummockgrasslandsdominatedbyspinifexorsandhillcanegrass 0.6 1.2 0.2 0.0 2.0 2.0 2 2 1 1

33.5 SedgelandassociatedwithHummockgrasslands 0.4 1.1 1.2 0.0 2.7 2.7 3 3 2 2

34.1 Openforestdominatedwetlands 6.0 3.4 5.3 1.7 16.4 16.4 1 1 1 1

34.2 Woodlanddominatedwetlands 2.5 4.0 0.2 1.3 8.0 8.0 1 1 1 1

34.3 Shrublanddominatedwetlands 1.3 3.3 2.3 0.0 6.9 6.9 1 1 1 1

34.4 Grassdominatedwetlands 1.0 4.0 0.0 0.0 5.0 5.0 2 2 1 1

34.5 Sedgelanddominatedwetlands 3.0 5.0 5.0 0.0 13.0 13.0 1 1 1 1

34.6 Sparselyvegetatedwetlands 1.1 3.1 0.0 0.0 4.2 4.2 3 3 2 2

35.1 Closedtoopenforestmangroves 0.0 0.0 0.0 0.0 0.0 0.0 3 3 2 2

35.3 Shrublandassociatedwithmangrovesandtidalsaltmarshes 0.0 0.0 0.0 0.0 0.0 0.0 3 3 2 2

35.4 Tidalsaltmarshes 1.0 2.9 0.2 0.0 4.1 4.1 2 2 1 1

35.5 Sedgelandassociatedwithmangrovesandtidalsaltmarshes 0.4 1.3 0.0 0.0 1.7 1.7 3 3 2 2

35.6 Sparselyvegetatedareasassociatedwithmangrovesandtidalsaltmarshes 0.9 1.9 0.2 0.0 3.0 3.0 3 3 2 2

36.1 Exotic&hardwoodplantation 22.3 1.5 1.2 1.0 26.0 26.0 1 1 1 1

37.1 Hoopplantations 3.0 2.0 0.0 0.0 5.0 5.0 3 3 2 2

38.4 Continuousdrylandcroppingandhorticulture 0.8 3.0 0.0 0.0 3.8 3.8 2 2 1 1

38.5 Discontinuousirrigatedcroppingandhorticulture 0.5 1.0 0.5 0.0 2.0 2.0 3 3 2 2

39.2 Lowtomoderatetreecoverinbuilt-upareas 2.0 3.0 2.0 1.0 8.0 8.0 3 3 2 2

40.4 Continuouslowgrassortreecover 0.5 4.0 0.5 0.0 5.0 5.0 2 2 1 1

41.4 Discontinuouslowgrassortreecover 0.5 2.0 0.5 0.0 3.0 3.0 3 3 2 2

42.6 Niltoverylowvegetationcover 1.0 1.0 0.0 0.0 2.0 2.0 3 3 2 2

43.6 Waterbodiesorverylowvegetationcover 0.0 0.0 0.0 0.0 0.0 0.0 3 3 2 2

Figure14:Vegetationhazardclassdescriptionsand80thpercentilepotentialfuelload.Source:QFES,2017.

37

Figure15:Lifeform,heightandrelativedensityofvegetationstructuralclasses.Source:QFES,2017.

Figure16:Vegetationstructuralclasses.Source:QFES,2017.

Density

Life form | Height 1. Closed 2. Mid-dense 3. Sparse 4. Very sparse

Trees

Tall 30 m+ 1.Treesclosed–middense

1.Treesclosed–mid-dense

2.Treessparse–verysparse


Medium 10–30m 1.Treesclosed–middense

1.Treesclosed–middense



Low 2–10m 1.Treesclosed–middense

1.Treesclosed–mid-dense



Sclerophyllous shrubs

Tall 2–8m 3. Shrubland 3. Shrubland 3. Shrubland 3. Shrubland

Medium 1–2m 3. Shrubland 3. Shrubland 3. Shrubland 3. Shrubland

Low <1m 3. Shrubland 3. Shrubland 3. Shrubland 3. Shrubland

Succulent shrub land

Low <2m 3. Shrubland 3. Shrubland 3. Shrubland 3. Shrubland

Low vegetation

Tussock grassland Low <2m

4.Grassland 4.Grassland 4.Grassland 4.Grassland

Hummock grassland Low <2m

4.Grassland 4.Grassland 4.Grassland 4.Grassland

Herbland Low <2m

5.Sedgeland 5.Sedgeland 5.Sedgeland 5.Sedgeland

Forbland Low <2m


Fernland Low <2m


Vineland Low <2m


Sedgeland Low <2m


Nil veg 6.Nilveg 6.Nilveg 6.Nilveg 6.Nilveg

Vegetation structure class Dominant life form Density

1.Treesclosed–mid-dense Trees Closedtomid-dense

2.Treessparse–verysparse Trees Sparsetoverysparse

3. Shrubland Shrubland Closedtoverysparse

4.Grassland TussockorHummockgrassland Closedtoverysparse

5.Sedgeland Herbland,forbland,fernland, vinelandorsedgeland

Closedtoverysparse

6.Nilveg Nilvegetation Nilvegetation

7. PROCESS FOR CALCULATING ASSET PROTECTION ZONES

38


39

7. Process for calculating asset protection zones

7.1 Introduction

Thissectionisapplicablewherealocalgovernment’splanningschemecontainsprovisionsthatidentifyacceptableradiantheatfluxlevelstoinformassetprotectionzones(APZs).Theradiantheatflux(kW/m2)outputisgeneratedbytheBushfireassetprotectionzonewidthcalculator(thecalculator).

Thecalculatorcanbeusedtodetermineradiantheatexposure,whichthenenablesanapplicanttoidentifythenecessarylotboundarylocationorbuildinglocationplansitingforexample,toachievetheradiantheatfluxoutcomessoughtbytheplanningscheme.

Alocalgovernmentmaywishtoreferapplicantstothistechnicalguidancedocumentorprovideinformationaboutthecalculatorinitsplanningscheme(e.g.asaplanningschemepolicy).ThecalculatoriscontainedinaMicrosoftExcelspreadsheet(.xls)andcanbedownloadedfromQueenslandGovernmentdataathttps://data.qld.gov.aubysearching‘bushfiredefendablespacewidthcalculator’.

Thecalculatorisalsoapplicabletootherassessmentsand,assuch,thissectionincludescontentonthoseadditionaluses.

7.2 Purpose of the Bushfire asset protection zone width calculator

Thecalculatorcalculatesfirelineintensity,radiantheatfluxandassetprotectionzonewidthusingeitherthebushfireproneareamappinginputdataorthesitespecificinputdata.

ThecalculatorisbasedontheviewfactormethodequationsdescribedinMethod2(Appendix2)ofAS3959–2018.ThecalculatoradaptsthismethodQueensland-specificparameterstoreflecttheinputparametersadoptedbytheStatePlanningPolicyJuly2017(SPP)mappingofbushfireproneareas(Leonardetal.,201448),includingFFDI(5%AEPfireweatherevent)andvegetationhazardclasses(VHCs).

Thecalculatorenablesrapidcalculationof:

1. Potential fireline intensity (kW/m)–therateofenergyreleaseperunitlengthoffirefront,regardlessofitsdepth

2. Bushfire prone area intensity classes–theclassapplicabletolandinaccordancewiththemedium,highandveryhighpotentialbushfireintensityclassesusedintheStatePlanningPolicyInteractiveMappingSystem(SPPIMS)bushfireproneareamapping

3. Radiant heat flux (kW/m2)–accordingtoseparationbetweendevelopmentandhazardousvegetation.

Note–Radiantheatexposure,togetherwithflamecontactandemberattack,arethemainmechanismsofbushfireattackandareimplicatedinlossoflifeandhousesanddamagetoinfrastructure49,50.Atcertainlevelsofradiantheatexposure(timedependent),pilotedignitionoftimberoccurs.51Housesexposedtolevelsofradiantheatwhichexceed40kW/m2arealsoexposedtoacombinationofbushfireattackmechanismsincludingdirectflamecontactandemberattack.

Adistanceneededtoachieve29kW/m2also:

• reducespotentialexposuretobushfireattack,particularlydirectflamecontact

• reducesthelikelihoodofpilotedignitionduetoradiantheatexposure

• improvesconsistencybetweenplanningandbuildingoutcomes

• reducespotentialforconflictsbetweenplanningandbuildingapprovals

• avoidsduplicationandregulatoryburdenonhomeowners.

Adistanceneededtoachieve10kW/m2alsofallsbelowthethresholdforpilotedignitionofdrytimberandfailureofplainglass.

7.3 Options for calculating the radiant heat exposure

Radiantheatexposuremaybecalculatedusingeither:

1. TheBushfireassetprotectionzonewidthcalculator(preferred),or

2. Method2ofAS3959¬–2018¬,subjecttotheadoptionofsite-specificvaluesofFFDI(5%AEPfireweatherevent),site-specificvegetationhazardclasses,modifiedmodellingofsurfacefuelloads52andeffectiveandsiteslopesdeterminedinaccordancewiththehazardassessmentprocessinsection5.4.

Theprocedureinvolvesthreesteps:

1. Identificationormeasurementofsitespecificbushfirehazardfactorsviathehazardassessmentprocessinsection5.4.

2. Measurementofthedistancebetweenthedevelopmentandhazardousvegetationviafieldmeasurementsorscaledplans.

3. CalculationofradiantheatexposureusingtheBushfireassetprotectionzonewidthcalculator(orMethod2ofAS3959¬–2018subjecttotheadoptionofthesitespecificvaluesandparametersdescribedabove).

7.4 Bushfire asset protection zone width calculator components

TheBushfireassetprotectionzonewidthcalculatorhasthreecomponents:

1. Inputvalues–userinputsnecessarytooperatethecalculatorcorrectly.

2. Outputvalues–fuelloadsforselectedinputvaluesand,whereapplicable,thecalculatorestimatesofradiantheatflux,firelineintensityand/orbushfireattacklevel.

3. VHCdata–vegetationhazardclasscharacteristicsincludingfuelloads,fuelcontinuityandpronetypeaccordingtoremnantstatus.

Figure17showsascreenshotofthecalculatorstartscreendisplayingtheinputandoutputvaluesfields.

48 Leonard, J, Opie, K et al. (2014), A new methodology for State-wide mapping of bushfire-prone areas in Queensland.49 Blanchi, R, Leonard J, et al. (2014), Environmental circumstances surrounding bushfire fatalities in Australia 1901–2011.50 Crompton, R et al. (2010), Influence of location, population, and climate on building damage and fatalities due to

Australian bushfire: 1925–2009.51 The long term unburnt condition represents greater than 10 years without burning. For further information see Leonard,

J, Opie, et al. (2014), A new methodology for State-wide mapping of bushfire-prone areas in Queensland.52 Total potential fuel loads (non-remnant) do not include surface, near-surface, elevated and bark fuel loads.

https://data.qld.gov.au

40


Parameter Process to identify calculator value

Fireweatherseverity(FWS) Determinedinaccordancewiththehazardassessmentstageinsection5.4.2(1)

Vegetationhazardclass(VHC)IdentifyVHCwithintheassessmentareafromthemappinginputsforVHCs(asdescribedinsection6)orviabotanicalsurveyinaccordancewiththehazard

assessmentstageinsection5.4.2(2)andsection6

RemnantstatusIdentifywhethertheVHCisremnantvegetationasdefinedinthe VegetationManagementAct1999(Qld)ornon-remnantvegetation.

SlopetypeIdentifywhethertheproposeddevelopmentisupslope ordownslopeofhazardousvegetationinaccordancewith section5.4.2(3)orclause2.2.5ofAS3959–2018)

Effectivefireslope Identifytheslope(degrees)ofthelandunderhazardousvegetationfor eachVHCinaccordancewithsection5.4.2(3)

SiteslopeIdentifytheslope(degrees)ofthelandbetweenthesiteandhazardous

vegetationforeachVHCinaccordancewithsection5.4.2(3)

Distancefromhazardous vegetation

Measuretheassetprotectionzonewidthbetweenthedevelopmentand adjacenthazardousvegetationinaccordancewithsection5.5.2(1)

7.5 Bushfire asset protection zone width calculator input parameters

Thecalculatorrequiresseveninputparameters.Valuesforeachoftheseparametersshouldbedeterminedbeforeusingthecalculator,asoutlinedbelow:

Whereareliabilityassessmenthasbeenundertakenandtheresultsofallstepsindicatetheinputmappingisreliable,themappinginputdatashouldbeusedforthecalculationofradiantheatflux.

Whereasitespecificassessmentofinputfactorshasbeenundertaken,thedatafromsteps1to3insection5.4.2shouldbeusedforthecalculationofradiantheatflux.

Furtherinformationinrelationtoeachparameteranditsroleinthecalculationofradiantheatfluxisoutlinebelow.

7.5.1 Fire weather severity

EquivalenttotheMcArthurForestFireDangerIndex(FFDI)535%AEPfireweatherevent.54

53 Total potential fuel loads (non-remnant) do not include surface, near-surface, elevated and bark fuel loads.

54 McArthur, AG (1967), Fire behaviour in eucalyptus forests.55 Noble, IR et al. (1980), McArthur’s fire-danger meters expressed as equations. 56 Cheney, NP et al. (2012), Predicting fire behaviour in dry eucalypt forest in

southern Australia. 57 McCaw, WL, et al. (2008), Existing fire behaviour models under-predict the rate

of spread of summer fires in open jarrah (Eucalyptus marginata) forest. 58 Cruz, MG et al. (2015) Empirical-based models for predicting head-fire rate of

spread in Australian fuel types.

59 McCaw, LW et al. (2012), Changes in behaviour of fire in dry eucalypt forest as fuel increases with age. 60 Noble, IR et al. (1980), McArthur’s fire-danger meters expressed as equations. 61 Cheney, NP et al. (2012), Predicting fire behaviour in dry eucalypt forest in southern Australia. McCaw, WL, et al. (2008), Existing fire behaviour models under-predict the rate of spread of summer fires in open

jarrah (Eucalyptus marginata) forest. Cruz, MG et al. (2015) Empirical-based models for predicting head-fire rate of spread in Australian fuel types. McCaw, LW et al. (2012), Changes in behaviour of fire in dry eucalypt forest as fuel increases with age. 62 Cruz, MG et al. (2015) Empirical-based models for predicting head-fire rate of spread in Australian fuel types.

Figure17:SPPBushfireassetprotectionzonewidthcalculatorstartscreen. Source:QFES,2019.

41

7.5.2 Vegetation hazard class (VHC)

ThevegetationwhichcontributestobushfirehazardandisclassifiedaccordingtoamodifiedversionofQueensland’sbroadvegetationgroups.55TheidentificationofVHCdetermineswhetherthevegetationcontributestobushfirehazard(pronetype).

ThepronetypeisacategoricalindicatorofthestatusofVHCwithrespecttoitscapacitytosupportasignificantbushfire.Thepronetypecategoriesare:

• ForestorShrubfires(1)

• Grasslandfires(2)

• Lowhazard(3).

AllQueenslandVHCsandtheirassociatedremnantandnon-remnantpronetypearelistedintheVHC_Datasheetofthecalculatorspreadsheet.

7.5.3 Remnant status

RemnantstatusisabinaryindicatorofwhethertheVHCisremnantvegetation,asdefinedintheVegetation Management Act 1999(Qld),orotherhazardous,non-remnantvegetation.Thedeterminationofremnantstatusestablishes:

• thetotalpotentialfuelloadvalueusedbythecalculator(‘Total(remnant)’or‘Total(Non-remnant)’)

• fuelcontinuity

• rateofspreadcalculationmethod.

ForcertainVHCs,thepronetypemayvaryaccordingtotheremnantstatusoftheVHC.Forexample,certainnon-remnantrainforestVHCsfrequentlyincludesignificantavailablefuelfromwoodyorweedspeciesandmayhaveapronetypeof1,whereasthesameremnantrainforestVHCmaybeconsidered‘lowhazard’.

Remnant vegetation,asdefinedintheVegetation Management Act 1999(Qld),includesrelativelyundisturbedwoodyornon-woodyvegetation.Woodyremnantvegetation–dominatedbytreesorshrubs–hasapredominantvegetationcanopy:

• coveringmorethan50percentoftheundisturbedpredominantcanopy

• averagingmorethan70percentofthevegetation’sundisturbedheight

• composedofspeciescharacteristicofthevegetation’sundisturbedpredominantcanopy.

Non-woody remnant vegetationhasnotbeencultivatedfor15years,containsnativespeciesnormallyfoundintheregionalecosystem,andisnotdominatedbynon-nativeperennialspecies.

ForremnantVHCs,thetotalpotentialfuelloadrepresentsthe80thpercentilefuelloadforeachfuelcategorybasedonthelongtermunburnt condition56(surfacefuel,near-surfacefuel,elevatedfuelandbarkfuelload).Totalpotentialfuelloads,includingsurface,near-surface,elevatedandbarkfuelloadsforeachVHCareindicatedintheVHC_Datasheetofthecalculatorspreadsheet.

Non-remnant vegetationincludeshazardouswoodyornon-woodyvegetationthathasthepotentialtosupportasignificant

bushfirewithinthedesignlifeofanewsettlementthatdoesnotmeetthestructuraland/orfloristiccharacteristicsforremnantvegetation.Thiscanincludenon-remnantrainforest,treeplantations,othernon-nativevegetation,regrowthvegetation,heavilythinned,loggedorsignificantlydisturbedvegetation,orvegetationwithinurbanorcroppingland.Totalnon-remnant,potentialfuelloadsforeachVHCareindicatedintheVHC_Datasheetofthecalculatorspreadsheet.57

Fuel continuityisabinaryindicatorofthecapacityofremnantornon-remnantvegetationtosupportacontinuousflamefrontunderarangeofweatherconditions.Continuousfuelvegetation(‘1’)generallyhasaconsistentdistributionoffuel.Discontinuousfueltypes(‘2’)includenon-hazardousvegetationorlanduses,suchasmangroves,built-upareasorwaterbodies.

Fuelcontinuityvariesaccordingtotheremnantornon-remnantstatusoftheVHC.Fuelcontinuityvaluesforbothremnantandnon-remnantcategoriesofeachVHCareindicatedintheVHC_Datasheetofthecalculatorspreadsheet.58

Fuelcontinuityalsovariesthecalculationoftheforwardrateofspread.RecentempiricalevidenceindicatesthattherateofspreadequationsusedinMethod2ofAS3959–2018underpredictrateofspread(andhencefirelineintensity)inopenforestandwoodlandswhenonlysurfacefinefuelsareusedinthecalculations.59,60,61Thereisstrongempiricalevidencewhichsuggeststhatnear-surfacefuelcharacteristics,togetherwithsurfacefuel,isabetterpredictorofrateofspreadformoderateandhighintensityfiresthansurfacefuelalone.62 To better reflectthecontributionofnear-surfacefueltorateofspread,surfacefuelload(w)iscalculatedasthesumofsurfaceandnear-surfacefuelsforopenforestandwoodlandVHCswherefueliscontinuous.Theresultisindicatedas‘TotalSurfaceFuelLoad’inthecalculator’soutputvaluestable.

7.5.4 Slope type

Slopetypereferstowhethertheeffectiveslopeisupslopeordownslope,inaccordancewithClause2.2.5ofAS3959–2018.Wheretheslopeofthelandcontaininghazardousvegetationisdownhillfromtheproposeddevelopmentorlotboundary,itisconsidered‘downslope’irrespectiveofthesiteslope.Wheretheslopeofthelandcontaininghazardousvegetationisuphill(orisflat)fromtheproposeddevelopmentorlotboundary,itisconsidered‘upslope’irrespectiveofthesiteslope.

7.5.5 Effective fire slope

Theeffectivefireslopeistheslopeunderhazardousvegetationindegrees(referalsotoAS3959-2018).Thisisavaluebetween1and20degreesdownslopeand1and15degreesupslope.

7.5.6 Site slope

Referstotheslopebetweenthesiteandhazardousvegetationindegrees(referalsotoAS3959–2018).Thisisavaluebetween1and20degreesdownslopeand1and15degreesupslope.

7.5.7 Distance from hazardous vegetation

Referstothehorizontaldistance(i.e.measuredinplan)ofthemanagedseparationarea(oftenreferredtoasassetprotection

42


zonewidth)betweentheedgeofhazardousvegetation(edgeofcanopyforforest,woodlandandheathtypeVHCs)andthepointidentifiedinaplanningschemeofbuildingprovisions.Thisislikelytobe:

• theclosestpointonalotboundaryorabuildingenvelope

• externalwallofabuilding

• supportingpostsorcolumnsforpartsofthebuildingthatdonothaveexternalwalls(e.g.carports,decks,landingsetc.),asperAS3959–2018.

ThisdistanceisinformedbytheVHCandslopecombinationbetweenthedevelopmentandthehazardousvegetation.

Increasingseparationreducestheintensityofbushfireattack(expressedasradiantheatflux)towhichadevelopmentisexposed.

7.6 Parametric constraints and variations

ThecalculatorincorporatesanumberofparametricconstraintswhichapplyinQueensland.Thisinclude:

1. Thecalculatordoesnotpermitmanipulationofunderlyingdata.Forexample,inaccordancewithaBushfireHazardAssessment(BHA),thecalculatordeliberatelyprohibitsthecreationofuser-definedfuelloads.Consequently,ausermustnominateaVHCaccordingtotheproceduredescribedinsection5.4.2todeterminepotentialfirelineintensityandradiantheatflux.Userscanonlyselectfromoneofthelevel2VHCsdescribedinFigure14.

2. ‘Slopetype’isaBooleanoperatorforeffectiveslope,namelywhethertheeffectiveslopeunderhazardousvegetationisupslopeordownslopeofthesite.

3. Effectivefireslopeinputsarelimitedtovaluesbetween1and20degreesfordownslopeand15degreesforupslope.Siteslopeinputsarelimitedtovaluesbetween1and20degrees.Firelineintensityandradiantheatcalculationsforlocationswithaneffectiveslopeofgreaterthan20degrees(downslope)or15degrees(upslope)maybeunreliable.Intheselocations,specialistassessmentiswarranted.Landwheretheeffectiveorsiteslopeis‘flat’musthaveaminimumslopeof1degree.

4. Bushfireattacklevelisnotcalculatedwheredistanceofthesitefromhazardousvegetationisgreaterthan100metresinaccordancewithAS3959–2018andLeonardetal.(2014).63

5. Firelineintensity,radiantheatfluxandbushfireattacklevelarenotcalculatedfornon-bushfireproneVHCs(grassfireproneVHCs[pronetype=2]orlowhazardVHCs[pronetype=3]).RefertotheVHC_DatasheetofthecalculatorspreadsheetforalistofpronetypesforeachVHCaccordingremnantstatus.

6. ThecalculatordealsonlywithdiscreteVHCs.RadiantheatfluxandassetprotectionzonewidthsformixedorheterogeneousVHCscannotbecalculatedusing

thetool.ManualcalculationsarerequiredwhereVHCsareheterogeneousormixed,e.g.VHC9.1/VHC16.1(60%/40%).

Thecalculator’sinbuiltparameterrulesprevententryofinappropriatevaluesandmanipulationofunderlyingdataandassumptions,suchasmodelconstantsandmodelequations.Thisensuresquality,consistencyandreliabilityofmodeloutputs.

Method2ofAS3959–2018alsoincludesseveralconstantsandassumptionsforwhichdefaultparametersaresuggested.Forthepurposesofproducingafit-for-purposetool,thecalculatoradoptsthefollowingdefaultvalues:

• Ambienttemperature(Ta):308K(35oC)

• Heatofcombustion:18,600kJ/kg

• Flametemperature(T):1200K64

• Flameemissivity( ):0.95

• Flamewidth(Wf):100m

• Windspeed(V):45km/hr(forshrubandheathVHCsonly)

• Vegetationheight(H):8m65(forshrubandheathVHCsonly).

Theabovevaluesarenotvisibletousersandcannotbeedited.

7.7 Bushfire asset protection zone width calculator software and hardware requirements

ThecalculatorrequiresuserstohaveinstalledacopyofMicrosoftExcel2007orlater.Usersmusthavesufficientsecurityprivilegestoenabletheuseofmacrosfromwithintheprogram.

Procedureforfirsttimeuse:

1. Savethefiletoalocalharddriveoranetworklocation.

2. Whenthecalculatorisopenedforthefirsttime,asecuritywarningwillappear.Selecttheenable content button to turn the calculator on.

3. Iftheenable contentbuttonisnotvisible,trust centre settingsmayneedadjustment.Todothis:

a.gotofile > optionsandselecttrust centre

b. in trust centreselectthetrust centre settings button andonthenextscreennavigatetomacro settings

c. under the macro settingsmenu,checkdisable all macros with notification

d. click OKtoconfirmthissetting

e.closethecalculatorandreopenittoapplythischange– the enable contentbuttonshouldappearatthetopoftheworksheetasperstep1.

4. Tosavethecalculator,theautomaticrecalculationofthecalculatorwillneedtobedisabled.Todothis:

a. gotofile > optionsandselectformulas

b. checkthatworkbookcalculationischeckedtomanual and that recalculate workbook before savingisunchecked.

63 Leonard, J, Opie, K et al. (2014), A new methodology for State-wide mapping of bushfire-prone areas in Queensland. 64 Sullivan, AL et al. (2003), A review of radiant heat flux models used in bushfire applications. 65 Upper estimate of vegetation height of shrub and heath VHCs based on available CORVEG data: Queensland Herbarium (2012). Queensland CORVEG Database, Version 4/2017. State of Queensland (Department

of Science Information Technology and Innovation). Brisbane, Queensland Government Data Portal <https://data.qld.gov.au/>, accessed August 2019.

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Figure18:SPPBushfireassetprotectionzonewidthcalculatoroutputvaluesandsampleresults.Source:QFES,2019.

7.9 Bushfire asset protection zone width calculator results

Thecalculatorallowsuserstoiterativelyassesstheeffectofchangestoinputvalues.Inparticular,theeffectofchangesinassetprotectionzonewidthonradiantheatfluxandbushfireattacklevel.

Reportedresultsinclude:

• Surfacefuelload(t/ha)

• Near-surfacefuelload(t/ha)

• Barkfuelload(t/ha)

• Elevatedfuelload(t/ha)

• Totaloverallfuelload(W)(t/ha)

• Totalsurfacefuelload66(w)(t/ha)

• Potentialfirelineintensity(kW/m)

• Radiantheatflux(kW/m2)

• Bushfireattacklevel,inaccordancewithAS3959–2018.

Modeloutputvaluesaredynamicandnotstored.Eachtimeauseraltersorentersnewinputvalues,resultswillneedtobere-calculatedbypressingthe‘Calculate’button.Userscanselect‘Copy Results’tocopytheinputsandresultsfordisplayinaBushfireManagementPlan(BMP)andtoassistindemonstratingcompliancewithassetprotectionzonewidthoutcomes.

Figure19showsanextractusingthe‘Copy Results’ button withinthetool.Copiedresultscanbeplaced/pasteddirectlyintoaBMPorequivalenttoexpediteassessmentoftheapplication.

66 Used to calculate the forward rate of spread for woodland and forest VHCs with fuel continuity.

7.8 Using the Bushfire asset protection zone width calculator

Thecalculatorrequiresseveninputsasdescribedinsection7.5:

1. Fireweatherseverity/FFDI(5%AEPfireweatherevent)–(CELLREF:D4)

2. Vegetationhazardclass(VHC)–(CELLREF:D5)

3. Remnantstatus–(CELLREF:D6)

4. Slopetype–(CELLREF:D7)

5. Effectivefireslope(eslope,degrees)–(CELLREF:D8)

6. Siteslope( ,degrees)–(CELLREF:D9)

7. Distancefromhazardousvegetation(d,metres)–(CELLREF:D10)

Figure18showsanexampleofthecalculatorinputscreenandexampledatainputs.

Oncethedatahasbeenentered,press‘Calculate’toassesswhethertheproposedseparationcomplieswiththeseparationoutcomessoughtbytheexampleplanningschemeprovisionsfoundintheSPPGuidanceMaterialforBushfire.N.B.Usersshouldusethe‘Calculate’buttonprovidedinthecalculatorsheetandnotMicrosoftExcel’scalculatebuttons.

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7.10 Default asset protection zone width formula

ThemodelprovisionswithinSPPguidancecontainadefaultseparationdistancetabletemplatethatcanbedevelopeduponrequesttoQueenslandFireandEmergencyServices(QFES).Thistablemaybeincludedwherealocalgovernmentseekstoprovideaquantifiableacceptableoutcomeforapplicantsthatremovestheneedtodetermineradiantheatfluxlevels.

APZwidthsarecalculatedusingamodifiedMethod2bushfireattacklevelassessmentfromAS3959-2018,usingconservativeinputs.WidthoutputsusethehighestFFDIandVHCfuelloadsforeachpotentialbushfireintensitycategorywithinthelocalgovernmentarea.Thisprocessandformulaaredescribedbelow:

1. Pre-treatmentoftheVHCdata.

AlldatashouldbeginassnappedtothesloperasterandprojectedinGDA1994AustraliaEqualAlbersprojection.

a. TheVHClayerasproducedisarasterdatasetwithanattachedlookuptable.ThetwocolumnsofinterestareVHC_NIBBLE,andFUELLOAD_NIB.Thesecolumnsaresplitusingthe‘ExtractbyAttributes’tool.Thisallowsthesetwofieldstobeusedwiththe‘Combine’tooltoproduceafastlookuptable.

b. TheBPAexistsasvectordata,butmustfirstbeconvertedtoraster.Using‘PolygontoRaster’,andselecting‘CLASS’asthevaluefield,withacellsizeof25,andsettingtheenvironmentvariable‘ProcessingExtent,Snapraster’tothe25mslopegrid,outputtoBPA_Mergedinageodatabase.

c. Theslopelayershouldbetreatedasthesnaprasterandclippedtotheareaofinterestforperformantoperationasitistypicallyawholeofstatedataset.

2. Combineusingthe‘Combine’tool.

a. Thefollowingshouldbecombinedandsavedinageodatabase:

> FFDI> Slope> FUELLOAD_NIB> VHC_NIBBLE> BPA_Merged.

ThiswillforcetherastertobesavedintheEsrigridformatandautomaticallyassociatealookuptablepreservingallvaluesfromtheinputraster.Thisinturnallowsfieldcalculationsbetweencolumns.Thisrasterwasnamed‘Combined_BPA_Slope_FFDI_VHC_Fuel’.

3. AddField.

a. Addafieldnamed‘Category’to‘Combined_BPA_Slope_FFDI_VHC_Fuel’.

4. CalculateFieldusingPython.

a. Thisprocesswillassignoneof12predefined categoriestoeachcellintherasterbasedonacombinationofslopeandBPA.FieldName‘Category’ExpressioncompareCalc(!slope_clipped!,!BPA_Merged!)

defcompareCalc(slope,bpa):

ifint(slope)<=4.9andint(bpa)==4:

return‘1’elif5.0<=int(slope)<=9.9andint(bpa)==4:return‘2’elif10<=int(slope)<=90andint(bpa)==4:return‘3’elifint(slope)<=4.9andint(bpa)==3:return‘4’elif5.0<=int(slope)<=9.9andint(bpa)==3:return‘5’elif10<=int(slope)<=90andint(bpa)==3:return‘6’elifint(slope)<=4.9andint(bpa)==2:return‘7’elif5.0<=int(slope)<=9.9andint(bpa)==2:return‘8’elif10<=int(slope)<=90andint(bpa)==2:return‘9’elifint(slope)<=4.9andint(bpa)==1:return‘10’elif5.0<=int(slope)<=9.9andint(bpa)==1:return‘11’elif10<=int(slope)<=90andint(bpa)==1:return‘12’else:return‘0’

5. Thetablemaybeexportedandinterrogated.

6. Shouldindividualcategorieswishtobequeried(e.g.a‘VeryHighBPA’and‘Highslope’),the‘ExtractbyAttributes’toolmaybeusedwithaSQLcommandofWhere‘Category=3’.

7. Thestepsfrom2onwardscanbesimplyandeasilymodelledtotheVHCorBPAtofacilitaterapidassessmentofanarea.

Figure19:Bushfireassetprotectionzonewidthcalculatoroutputvaluesandsampleresults.Source:QFES

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8. PROCESS FOR PREPARING A BUSHFIRE MANAGEMENT, VEGETATION MANAGEMENT OR LANDSCAPE

MAINTENANCE PLANS

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8. Process for preparing a Bushfire Management, Vegetation Management or Landscape Maintenance Plans

8.1 Introduction

Thissectionisapplicablewherealocalgovernment’splanningschemecontainsprovisionsthatenableanapplicanttoprepareaBushfireManagementPlan(BMP)todemonstrateachievementoftheoutcomescontainedintheplanningscheme,forexample:

• reportingontheoutcomesofaBushfireHazardAssessment(BHA),or

• proposingdesignandmanagementmeasuresthatavoid,minimiseormitigatebushfireattackrisktoanacceptableortolerablelevel,or

• proposingmitigationstrategiesincludingvegetationmanagementorlandscapemanagement.

Assuch,aplanningschememayalsoincludeprovisionsforthepreparationofaVegetationManagementPlan(VMP)orLandscapeManagementPlan(LMP).

AlocalgovernmentmaywishtoeitherreferapplicantstothistechnicalguidancedocumentorprovideinformationaboutpreparingaBMP,VMPorLMPinitsplanningscheme(asaplanningschemepolicy,forexample).

8.2 Management plan reporting

Thefollowinginformationshouldbeincludedaspartofallmanagementplans:

• sitedetails,suchasrealpropertydescriptionandstreetaddress

• descriptionoftheproposeddevelopment

• detailsofanyrelevantpreviousapprovals.

8.3 Bushfire hazard reports and Bushfire Management Plans

Abushfirehazardreport–typicallycontainingtheresultsofaBHA–isoftenakeycomponentofaBMP.Thisbushfirehazardreport,ortheBMP,istoincludemapsandplansthatshow:

• vegetationhazardclass(VHC)surveylocationswithinthesiteassessmentarea

• theextentandconfigurationofVHCswithinthesiteassessmentareabeforeandafterdevelopment,includinganyvegetationtoberetained,revegetationareasand/orenvironmentaloffsets

• theextentofbushfireproneareas(firelineintensity)andpotentialimpactbuffer,potentialflamelengthandpotentialrateofspreadinrelationtothedevelopment.

AbushfirehazardreportshoulddetailtheassessmentmethodsandoutcomesofanyBHAthathasbeenundertakeninaccordancewiththehazardassessmentguidanceinsection5.4andistodocumenttheresultsofthatBHA,including:

• resultsofanyreliabilityassessment

• potentialfirelineintensity,potentialflamelength,potentialrateofspreadandradiantheatflux.

ABMPalsowillincludedetailsoftheproposedbushfireprotectionmeasures,suchas:

• separation,includingrecommendedassetprotectionzone,suchasdimensions

• siting,includingbuildingenvelopes

• landscapedesignandmanagement,andvegetationmanagementincludingfuelmanagementareas/zones

• accessandevacuationroutes

• watersupply.

8.4 Vegetation Management Plans

ThepreparationofaVMPmayincludemeasuresforthelong-termmanagementofvegetationinrehabilitationorrevegetationareasorofvaluablevegetation(forexample,whereclearingistobeminimised)toreducetheongoingriskofbushfiresonthesiteandinsurroundingareas.

Fuelmanagementdoesnotnecessitatetheremovalofallvegetation.Vegetationmanagementstrategiesmayinclude:

• retainingtreesaswidelyspacedindividualsorinclumpsthatcontributetolandscapedesignoutcomes,withoutsignificantlyincreasingfuelloadsortheseverityofbushfirehazard

• selectiveremovalofvegetationwhichfacilitatesemberattack,selectiveclearingofnativeunderstoreyvegetationandreplacementwithlow-flammabilityspecies(referFigure20).

8.5 Landscape Management Plans

ThepreparationofanLMPmayincludemeasuresforthedesignandlong-termmanagementoflandscapingwithinbushfireassetprotectionzones(APZs)tominimisethelevelofbushfireriskormechanismsofbushfireattack,providingareducedfuelareawhichiscompatiblewiththeassetprotectionzone.

Thesemeasuresmayinclude:

• landscapedesignthatreducesvulnerabilitytobushfireattack

• plantselectionthatavoidsorminimisesopportunitiesforignitionoflandscapingfeatures

• long-termlandscapemanagementarrangementsthatreduceexposuretobushfireattack.

Inaddition,theuseofbarriersthatlimittheimpactofdirectflamecontact,radiantheat,emberattackandwindcansupplementmeasurestargetingvegetationandfuelmanagement.

Strategiesthatsupporteachofthesemeasuresaredetailedbelow.

8.5.1 Landscape design

• Establishingaminimalfuelaroundbuildingsofanominal10metres.

• Ensuringflammablematerialsarenottouchingorclosetovulnerablepartsofbuildingssuchaswindows,decksandeaves.Thesematerialsinclude:

47

> flammableshrubsandtrees

> flammablemulchesorfences

> treeswherethecanopyoverhangsthebuilding

> climbingplantsorvinesincontactwithexternaltimberfascia,pergolas,posts,beamsand/ortrellis.

• Establishingnon-flammablefeaturessuchastenniscourts,swimmingpools,dams,maintainedlawns,drivewaysorpaths.

• Usingpathsanddrivewaysmadeofnon-combustiblematerialssuchasclay,concrete,gravelandpebbles.

• Ensuringpotentialhazardousfeaturesandout-buildingssuchassheds,coopsandmachinerystoragesaresitedwellawayfromthedevelopmentandpreferablyshieldedfrombushfireattackbyotherbuildingssotheyarenotconsumedandcontributetohazard.

• Ensuringthelayoutofgardenbeds,lawnsanddrivewaysorpathsareconfiguredtoavertthecontinuityoffuelloadswithinAPZs.ContinuousvegetationwithinAPZsassiststhespreadoffire.Byseparatinggardenbedsandclumpsoftreesorshrubswithareasoflowfuel,fuelcontinuityisbrokenup,reducingthepotentialrateofspreadandfireintensity.Examplesincludeplacingmaintainedlawns,pathwaysorpondsbetweenclumpsoftreesorshrubsandgardenbeds.

• Creatinggapsincanopytreesthroughselectiveclearingofexistingvegetationorplantinglayoutorensuringtreecanopiesdonotoverlap.Thismeasurereducesthepotentialspreadofcrownfires.

• Establishinglawnsubstitutesincludingnon-flammablegroundcoverssuchasdecorativestoneorgravel.

8.5.2 Plant selection

• Plantingormaintainingplantspecieswhichminimiseleaflitterdroptoreducetheaccumulationofsurfacefuel(e.g.persistentleaflitter).

• Plantingormaintaininglow-flammabilityspecies(e.g.appropriatelocalnatives)thatarealsoadaptedtolocalconditionsandenhancehabitatvaluesforwildlife.

Note–Environmentalweedsareoftengardenescapeesandcontributetofuelloads,increasingbushfirehazard.Examplesofthisinclude,lantana(Lantanacamara)andgambagrass(Andropogongayanus).

• Plantingormaintainingspecieswithattributes(suchasavoidingspecieswithfibrousbark)whichreducetheeaseofcombustion,minimisecontributiontopotentialfuelloadoractasapotentialbarrier,reducingtherateoffirespread.

• Figure20indicatesthecharacteristicsoflowflammabilityspeciesandtheeffectofplantattributesontheirperformanceinbushfiresituations.67

67 Ramsay, GC, and Rudolph, LS (2003), Landscape and building design for bushfire areas.68 Middlemann, MH (ed.) (2007), Natural hazards in Australia: Identifying risk analysis requirements.69 Neldner, VJ, Niehus, RE et al. (2015), The vegetation of Queensland: Descriptions of broad vegetation groups.

Version 2.0.

Plant attribute Effect Design measure

Foliagemoisturecontent Leaveswithhighermoisturecontentretardignitionandslowtherateofcombustion

Selectspecieswithhighleafmoisturecontent(e.g.rainforestspecies,succu-lentsandsemi-succulents)

Foliagevolatileoilcontent Foliagewithhighervolatileoilcontentignitemorereadilyandenhanceignitionofsurroundingvegetation,eventhoughvolatileoilsthemselvesdonotcontributesignificant-lytototalradiantheat

Selectspecieswithlowervolatileoilcontent68,69

Foliagemineralcontent Foliagewithhighermineralcontenttendtobelessflammable(e.g.Amyemasppmistle-toes)

Speciesselectionshouldfavourspecieswithhigherleafmineralcontent

Leaffineness Theratioofarea-to-volumeofleavesisoneofthemainfactorsaffectingeaseofignitionandintensityofburning.Finerleaves(greaterareatovolumeratio)tendtoigniteandburnmoreeasilythanbroaderleaves

Speciesselectionshouldfavourbroad-leafedspecies

Densityoffoliageandcontinuityofplantform

Specieswithcontinuous,denserfoliagecanactasabarriertowind-borneembersandradiantheat;however,increaseddensitycanincreaseflammability.Specieswithopenbranchingandlowfoliagedensityarelesseffectiveasabarrier,thoughcanbelessflammable

Selectspeciesonacase-by-casebasis

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Plant attribute Effect Design measure

Heightoflowestfoliage Shrubandtreespecieswithpersistentlowheightfoliagearemorelikelytobeignitedbysurfacefires,allowingthespreadoffiresintothecanopyabove

Speciesselectionshouldfavourspecieswhichcanbemaintainedorprunedtoreducepersistent,near-groundfoliage

Sizeofplant(volumeandspread) Theeffectofplantsizevariesaccordingtovolumeorspread.Specieswithagreaterspreadtendtobemoreeffectiveasabarriertothediffusionofradiantheatthannarrowertreeswiththesamevolume.Specieswithagreatervolumecanresultinincreasedemberattack,radiationandflameifignited.Forexample,narrowcolumnartreesarelesseffectiveasabarrierthanwidertreeswiththesameoverallvolume

Speciesselectionshouldensureplantsize(volumeandspread)doesnotincreaseignitionlikelihood

Deadfoliageonplant Persistentdeadleavesandwoodytwigsincreaseflammability

Speciesselectionshouldfavourspecieswhichhavealowvolumeofpersistentdeadleavesandwoodymaterialorcanbemaintainedorprunedtoreduce persistent,deadleavesandwoodymaterial

Barktexture Loose,flaky,stringy,paperyorribbon-likebarkcontributetoladderfuelswhich:• cancontributetodestructivecrownfires• actasapotentialsourceofflame,radiantheatandemberattack

Avoidspecieswithpersistentloose,flaky,stringy,paperyorribbon-likebark.Speciesselectionshouldfavoursmooth-barkedandtightly-heldbarkspecies

Potentialavailablesurfacefuel Theavailabilityofsurfacefuelisafunctionofvolume(quantity)andfineness.Thefirelineintensityincreasesinproportiontoavailablefinefuelquantity.Finefuelincludesdeadfallenmaterialsuchasleaves,bark,twigsandbranchesupto6mmindiameter(forest)andgrassgreaterthan5cminheight(grass-lands).Coarsefueligniteslessreadilybutmayburnforlonger

Speciesselectionshouldfavourspecieswhichdonotcontributesignificantlytopersistent,finegroundfuel

Figure20:Characteristicsoflowflammabilityspeciesandeffectonperformanceinbushfiresituations.Source:Ramsay, GC, and Rudolph, LS (2003), Landscape and building design for bushfire areas. (Same as footnote 67)

8.5.3 Landscape management

• Ensuringstreetandroadvergesandnaturestripscontaininghazardousvegetationareregularlypruned,mownorgrazed.

• Removingaccumulatedleaflitterandwoodydebrisatregularintervals.

• Keepingareasbeneathretainedorplantedtreesandshrubclearedoffuel.Thismayincludevegetationmanagementmeasuressuchas:

> canopyliftingtoreducenear-surfaceorladderfuelloadsandreduceflameheights

> clearingofunderstoreyvegetation

> removalofaccumulatedlitterandwoodydebris

> removalofloosebarkanddeadlimbsfromstandingtrees.

• Regularmowingorslashingofgrasstolessthan10centimetresinheight.

• Availabilityofreliableandsufficientwaterandinstallationofirrigationandsprinklersystemstocreateawell-wateredlandscape.

8.5.4 Barriers

• Selectionoflow-flammabilitytreesandshrubswithgoodbarrier-formingattributes,suchasrainforestspecies.

• Useofnon-combustiblefencesandretainingwalls,suchasstonewalls.

• Positioningnon-combustiblewatertanksatkeylocationstoactasradiantheatbarriers.

• Positioningbarrierplantingswheretheyarelikelytobemosteffective.Vegetationbarriersshouldbelocatedatasuitabledistancefrombuildingsorflammableobjects(suchasfences)sothat,ifignited,theflamescannotcomeintocontactwiththeseelements.

499. INFORMATION THAT MAY INFORM

DEVELOPMENT CONDITIONS

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9. Information that may inform development conditions

9.1 Static water supply

Whereaplanningschemecontainsanassessmentbenchmarkfortheprovisionofanappropriatestaticwatersupply,adevelopmentconditionmayspecifyhowthisistobeprovided.

Anappropriatestaticwatersupply(inbushfireproneareaswherereticulatedsupplyisnotprovided)tosupporteffectiveemergencyservicesresponseincludesawatertankthatisavailablesolelyforfirefightingpurposesandcanbeaccessedbyfirefightingappliances.Thewatertankistobeprovidedwithin10metresofeachbuilding(otherthanaclass10building),which:

a) iseitherbelowgroundlevelorofnon-flammableconstruction

b) hasatake-offconnectionatalevelthatallowsthefollowingdedicated,staticwatersupplytobeleftavailableforaccessbyfirefighters:

i. 10,000litresforresidentialbuildings

ii. forindustrial,commercialandotherbuildings,avolumespecifiedinAS2304–2011Waterstoragetanksforfireprotectionsystems

c) isprotectedfrombushfireattack,includingshieldingoftanksandpumpsinaccordancewithAS2304–2011Waterstoragetanksforfireprotectionsystems

d) allowsmediumrigidvehicle(15tonnefireappliance)clearaccesswithinsixmetresofthetank

e) ifservicedbyaruralfirebrigade,isprovidedwithruralfirebrigadetankfittingsofa50millimetreballvalveandmalecamlockcouplingand,ifunderground,anaccessholeof200millimetres(minimum)toaccommodatesuctionlines

f) isclearlyidentifiedbydirectionalsignageatthestreetfrontage.

9.2 Assembly and evacuation areas

Whereaplanningschemecontainsanassessmentbenchmarkfortheprovisionofasafeassemblyorevacuationarea,adevelopmentconditionmayarticulatehowthiscouldbeachieved.

Asafeassemblyorevacuationareamaybeasuitablealternativetoanevacuationroute,wherethesiteisinanisolatedlocation,andanyevacuationroutewouldbelongorpassthroughthebushfirepronearea.Asafeassemblyorevacuationareawouldinvolve:

• Establishingthesafeassemblyorevacuationareawithinthedevelopmentsiteandoutsidetheidentifiedbushfireprone area.

• Directroute/stothedesignatedareaaredesignedtoensure:

> roadshavesufficientcapacityfortheevacuatingpopulation

> occupantsaredirectedawayfromratherthantowardsorthroughareaswithagreaterpotentialbushfireintensity

> minimisingthelengthofroutethroughbushfireproneareas

> compliancewithAS3745–2010Planningforemergenciesinfacilitieswheredeemedappropriateforisolateddevelopments.

9.3 Protective landscape treatments

Developmentsshoulddemonstratethatlandscapingandopenspaceshaveapotentialavailablefuelloadoflessthan8tonnes/hectareonaggregate,andfuelstructurethatremainsdiscontinuous.Theserequirementsmaybeincludedinaplanningschemewherelandscapingandopenspacesaretocompriseprotectivelandscapetreatments.

9.4 Asset protection zones for vulnerable uses, storage or manufacture of materials that are hazardous and community infrastructure for essential services

SiteplanningwillformparttheriskmitigationapproachwherethesedevelopmentsareunavoidableinaBushfireProneArea,andconditionsunderPolicies6,7and8ofthisdocumentaremet.SiteplanningmayincorporateAPZsaspartofselectedriskmitigationtreatments.Thismayincludeadevelopmentfootprintplanthatisseparatedfromtheclosestedgetotheadjacentmappedmedium,highorveryhighpotentialbushfireintensityareabyadistance(APZwidth)thatachievesaradiantheatfluxlevelof10kW/m2orlessatalldevelopmentfootprintboundaries.

Section7inthisdocumentprovidesguidanceregardingtheprocessforcalculatingassetprotectionzones.

Note–Inadditiontothisguidance,theWorkHealthandSafetyAct2011andassociatedRegulationandGuidelines,theEnvironmentalProtectionAct1994andtherelevantbuildingassessmentprovisionsundertheBuildingAct1975containrequirementsforthemanufactureandstorageofhazardoussubstances.InformationisprovidedbyBusinessQueenslandontherequirementsforstoringandtransportinghazardouschemicals,availableat:www.business.qld.gov.au/running-business/protecting-business/risk-management/hazardous-chemicals/storing-transporting

Note–Existingclearedareasexternaltothesitemayonlybeusedincalculatingnecessaryseparationwheretenureensuresthatthelandwillremainclearedofhazardousvegetation(forexamplethelandisaroad,watercourseorhighlymanagedparkinpublicownership).

http://www.business.qld.gov.au/running-business/protecting-business/risk-management/hazardous-chemicals/sto



5110. EXPERTISE

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10. Expertise

10.1 Introduction

Thissectionisapplicablewherealocalgovernment:

• proposestoundertakeareviewofstatewideStatePlanningPolicyInteractiveMappingSystem(SPPIMS)bushfireproneareamappingaspartofplanning

• proposestoundertakeariskassessmentforbushfireinaccordancewithAS/NZ31000-2018Riskmanagement-guidelines,or

• containsprovisionsinaplanningschemefortheundertakingofaBHA,VegetationHazardClassAssessmentorBMPandpreparationofaBushfireHazardReportaspartofadevelopmentapplication.

10.2 Suitably qualified and experienced

Thepreparationoftheseplanningschemeprovisionsorapplicant-initiatedassessmentsandreportsshouldbeprepared(orpeer-reviewed)bysuitablyqualifiedandexperiencedpeople.Thesepeopleshouldhavethefollowingqualificationsandexperienceasastartingpoint:

• degree(AQFlevel8)qualificationsinenvironmentalscience,environmentalmanagement(orequivalentdiscipline)

• demonstratedexperienceinbotanicalsurveyandspatialanalysismethods,includinguseofgeographicinformationsystems(GIS)software

• demonstratedexperienceintheassessmentofbushfirehazardandrisksortechnicalqualificationsinenvironmentalscience,environmentalmanagement(oranequivalentdiscipline)

• demonstratedrelevantindustryexperienceintheassessmentofbushfirehazardandrisksforaminimumfiveyears.

Wherealocalgovernmentproposestoincludeadviceabouttheprocessforpreparationofapplicant-initiatedassessmentsinitsplanningscheme(asaplanningschemepolicy,forexample),itisrecommendedthatadviceonthenecessaryexpertisealsobeincluded.

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11. Acronyms and abbreviations

APZ Assetprotectionzone

AEP Annualexceedanceprobability

AS3959–2018AustralianStandard3959–2018Constructionofbuildingsinbushfire-proneareas

BPA Bushfirepronearea

BMP BushfireManagementPlan

BVG Broadvegetationgroup

FDI FireDangerIndex

FFDI ForestFireDangerIndex

FWS Fireweatherseverity

IMS Interactivemappingsystem

LMP LandscapeManagementPlan

MCU Materialchangeofuse

NCC NationalConstructionCode

QFES QueenslandFireandEmergencyServices

RH Relativehumidity

RAL/ROL Reconfigurealot/reconfigurationoflot

SPP StatePlanningPolicy

SPPmap Statewidemapofbushfireproneareas(availableviatheSPPIMS)

SPPmapinputdataStatewidemapofbushfireproneareasinputdatae.g.FFDI(5%AEP),maximumlandscapeslopeandvegetationhazardclass

VHC Vegetationhazardclass

VMP VegetationManagementPlan

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12. Glossary

Asset Protection Zone (APZ)–aspecifiedareaoflandthatenablesemergencyaccessandoperationalspaceforfirefighting.VegetationismodifiedandmaintainedwithintheAPZtoreducefuelloadandmechanismsofbushfireattacksuchasflameandradiantheat.Thezonemayincludeacombinationofelementssuchasperimeterroad,firetrailandworkingareaandopenspacewherevegetationismanaged.

Note–Theassetprotectionzoneneednotbemaintained‘fuelfree’.Sensiblelandscapedesigncanensureabalancebetweenlandscapedesignoutcomesandminimisingthevulnerabilitytobushfireattack.Refertosection8.5inthisdocumentforguidanceonlandscapedesignandvegetationmanagement.

Note–Theassetprotectionzoneconsideredaspartofaplanningdevelopmentapplicationisdifferentfromthesitingofabuildingaspartofdesigningandconstructingthebuildingtoreducetheriskofignitionfromabushfire,appropriatetotheintensityofthebushfireattackonthebuildingandtheassociatedrequirementsprescribedinAS3959–2018Constructionofbuildingsinbushfireproneareasaspartofabuilding

developmentapplication.

Bushfire–agenericAustraliantermforanunplannedvegetationfirewhichincludesgrassfires,forestfiresandscrubfires.Bushfiresaresynonymouswiththeterms‘wildfire’(NorthAmerica,Asia,Europe,NewZealand)and‘veldtfire’(SouthAfrica).

Bushfire hazard–ahazardcanbedefinedasaconditionevent,orcircumstancethatcouldleadtoorcontributetoanunplannedorundesirableevent.Inthecontextofbushfires,hazardsincludesmoke,radiation,hotgases,airborneparticles,burningembers,fire-inducedwindsandflames.

Bushfire prone area–definedintheStatePlanningPolicy(SPP)asthespatialrepresentationofthenaturalhazardareaofbushfire,towhichthe‘Naturalhazards,riskandresiliencestateinterest’applies.Abushfireproneareaissometimesreferredtoasthebushfirehazardoverlay,

Note–A‘designatedbushfirepronearea’forapplicationofthebushfirebuildingcodesisdifferentfromthe‘bushfirepronearea’usedforlanduseplanningpurposes.However,itiscommonforlocalgovernmentsto

adoptthe‘bushfirepronearea’asthe‘designatedbushfirepronearea’.

A‘designatedbushfirepronearea’isdefinedbytheAustralianBuildingCodesBoardasanareadesignatedunderastatutorymechanismasbeingsubjectto,orlikelytobesubjectto,bushfires.Thedeclarationtypicallyoccursthroughstatebuildinglegislation.InQueensland,section12oftheBuildingRegulation2006(QLD)identifiesthatalocalgovernmentmay,inalocalplanninginstrument,designateallorpartofitsareaasadesignatedbushfireproneareafortheBuildingCodeofAustralia(BCA)orQueenslandDevelopmentCode(QDC).

BuildingdevelopmentapplicationsinadesignatedbushfireproneareaarerequiredtomeetthemandatorybushfireprovisionsintheNationalConstructionCode(NCC)series(BCA)andinAS3959–2018Constructionofbuildingsinbushfire-proneareas.BushfireprotectionprovisionsintheNCCapplytoClass1,2and3residentialbuildingsandaccommodationbuildingsandassociatedClass10astructuressuchasgarages,shedsandcarports.

TheNCCperformancerequirementisthat“abuildingthatisconstructedinadesignatedbushfirepronearea,musttothedegreenecessary,bedesignedandconstructedtoreducetheriskofignitionfromabushfire,appropriatetothepotentialforignitioncausedbyburningembers,radiantheatorflamegeneratedbybushfire;andintensityofthebushfireattackonthebuilding.”

TheNCCperformancerequirementisdeemedtobemetwherethebuildingcomplieswithAS3959–2018.AS3959–2018containsprovisionswhichcanbeusedinconstructiontoresistbushfires,toreducetherisktolifeandminimisetheriskofpropertyloss.Theseprovisionsincluderequirementsforburningdebrisandemberprotection,controlsonthecombustibilityofexteriormaterial,andtheprotectionofopenings,suchaswindowsanddoors.

AlocalplanninginstrumentdoesnototherwisedealwithbuildingmatterscoveredbyAS3959–2018.

Effective slope–theslopeundervegetationthatcontributestobushfirehazardinrelationtotheproposeddevelopmentorsiteboundary.Wheremultipleslopesoccurinrelationtoaproposeddevelopmentorsiteboundary,themaximumslopeunderhazardousvegetationisused.

Exposure–theelementswithinagivenareathathavebeen,orcouldbe,subjecttotheimpactofaparticularhazard.Exposureisalsosometimesreferredtoasthe‘elementsatrisk’andcouldincludethenumberandcharacteristicsofthevaluesorassetsexposed,wherethevaluesorassetscouldbetangibleorintangibleaspectsofenvironmental,social,cultural,economicorpolitical/reputationaldimensions.

Fine fuel–thatcomponentofthefuelthatburnsintheflamingzoneofabushfire.Practically,thisincludesdeadplantmaterialsuchasgrass,leaves,barkandtwigslessthan6millimetresthickandliveplantmateriallessthan2millimetresthick.Finefuelsaretypicallydescribedinstrataassurface,near-surface,elevated,bark(ontreeboles)andcanopyfinefuels.Thisdocumentonlyreferstofinefuel,soanyreferencetofuelshouldbetakentomeanfinefuel.

Fire weather severity–isequivalenttotheForestFireDangerIndex(FFDI),asdefinedinAS3959–2018,ascalibratedbythedocument‘AnewmethodologyforState-widemappingofbushfireproneareasinQueensland’.Itisbasedonathree-hourly,83kilometregriddedpredictionoftheFFDIfromlong-termspatialweatherproductsproducedbytheAustralianBureauofMeteorology(BoM).

FFDI–ForestFireDangerIndex.TheFFDIisameasureofthefrequencyofbushfireweathereventsthatinfluencethenatureofbushfirebehaviour.Theycanbemitigatedthroughlanduseplanning.TheFFDIisequivalenttoa5%annualexceedanceprobability(i.e.5%chanceofoccurringinanygivenyear).Theindexintegratesthecombinedeffectofarangeofweathervariablesincludinglong-termdryness,recentprecipitation,currentwindspeed,relativehumidityandtemperature.TheFFDI(5%AEP)indexhasbeencalculatedusingadjustedweatherdatatoreflectprojectedchangestoclimateby2050.

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Hazard–aprocess,phenomenonorhumanactivitythatmaycauselossoflife,injuryorotherhealthimpacts,propertydamage,socialandeconomicdisruptionorenvironmentaldegradation.72Inthecontextofbushfires,hazardsincludesmoke,radiation,hotgases,airborneparticles,burningembers,fire-inducedwindsandflames.

Hazardous vegetation–vegetationthatcontributestofinefuelsandresultsinabushfirehazardwhenburnt.Areasthataremappedaseitherveryhigh,highormediumpotentialbushfireintensityincludepotentiallyhazardousvegetationthatcouldsupportasignificantbushfire.Thisvegetationisclassifiedandmappedashavingavegetationhazardclass.

Head fire–thepartofafireperimeterwheretherateofspread,flameheightandintensityaregreatest,usuallythepartofthefireperimetermostdownwindorupslope.

Maximum landscape slope–themaximumpotentialslopeofthelandscape,overa25metredistance,thatcouldinfluencetherateoffirespread.Thistermissynonymouswith‘effectiveslope’inthisdocument.

Mitigation–measurestakeninadvanceofabushfireeventthataimtodecreaseoreliminatethebushfire’simpactonsocietyandtheenvironment.

Potential fireline intensity–therateofenergyreleaseperunitlengthoffirefront,regardlessofitsdepth.Severalassumptionsunderpintheinputsforcalculatingthepotentialfirelineintensity,including:

• thefireignitionmustoccurinasuitabletimeandplace

• thefiremustarrivefullydevelopedatthetimeofthemaximumdailyFFDI

• theslopeintheadjacentgridmustbeatthemaximum

• thewinddirectionmustalignwiththeslope

• thefuelloadatthetimeofthefiremustmatchthepotential fuel load

Therefore,whilethefireweatherseverityis5%AEPlikelihood,whencombinedwiththeabovefactors,theactuallikelihoodislessbyanorderofmagnitude.

Potential impact buffer–thespatialrepresentationoftheportionsofabushfireproneareathatcompriselandsatriskofsignificantbushfireattackfromembers,flamesorradiantheat.Thepotentialimpactbuffersurroundsareasmappedaseitherveryhigh,highormediumpotentialbushfireintensity.

Risk assessment–theprocessofriskidentification,riskanalysisandriskevaluationdefinedinAS/NZSISO31000:2018andtheQueenslandEmergencyRiskManagementFramework(QERMF).

Site slope–theaverageslopeofthegroundbetweentheedgeoftheproposeddevelopmentorsiteboundaryandtheedgeofhazardousvegetation.

Vegetation hazard class–thevegetationthatcontributestobushfirehazardandisclassifiedaccordingtoamodifiedversionofQueensland’sbroadvegetationgroups.

Vegetation hazard area–tree,shrub,grassorcultivatedvegetationthatrepresentsapotentialfirehazard,andincludeshazardousvegetationandgrassfireproneareas.

Vulnerability–thecharacteristicsandcircumstancesofacommunity,systemorassetthatmakeitsusceptibletothedamagingeffectsofahazard.

70 Australian Emergency Management Institute (2015), National Emergency Risk Assessment Guidelines.71 Leonard, J., Newnham, G, et al. (2014), A new methodology for State-wide mapping of bushfire prone areas in

Queensland.72 United Nations Office for Disaster Risk Reduction (2017).

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13. Figures

Figure1:TherelationshipbetweentheStatePlanningPolicy(SPP)andtheSPPnaturalhazardsguidancematerial

Figure2: Overviewofbushfireplanningandassessmentprocesses

Figure3:Exampleofamappedbushfirepronearea,includingthepotentialimpactbuffer(landwithin100linearmetresofmappedvegetationofgreaterthan4,000k/Wmfirelineintensity)

Figure4: Methodforcalculationofpotentialfirelineintensity

Figure5: Potentialeffectsofradiantheat

Figure6:Vegetationhazardclass(VHC)codecomponents:broadvegetationgroupandvegetationstructureclass

Figure7. Characteristicsofappropriatesub-hectarearearemoval

Figure8: Characteristicsofeffectivefuelloaddowngradesforsmallpatches

Figure9. Characteristicsoftheeffectiveremovalofnarrowcorridors

Figure10. Characteristicsofeffectivesmallfragmentremoval

Figure11: AnoverviewoftheBushfireHazardAssessment(BHA)process

Figure12:Statewidemapofvegetationhazardclass(VHC)(left)andexampleofagroundtruthedmapofobservedVHCs(right)

Figure13:Fuelloadbasedonstatewidemapofvegetationhazardclass(VHC)(left)andexampleofafuelloadrasterbasedonobservedVHCs(right)

Figure14:Vegetationhazardclassdescriptionsand80thpercentilepotentialfuelload

Figure15: Lifeform,heightandrelativedensityofvegetationstructuralclasses.

Figure16: Vegetationstructuralclasses

Figure17: Bushfireassetprotectionzonewidthcalculatortoolstartscreen

Figure18:Bushfireassetprotectionzonecalculatordatainputvaluesandexampledatainputs

Figure19:Bushfireassetprotectionzonewidthcalculatoroutputvaluesandsampleresults

Figure20:Characteristicsoflowflammabilityspeciesandeffectonperformanceinbushfiresituations

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