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Bushfire Report
Bushfire Risk Assessment
and
Bushfire Risk Management Plan
for
A house
at
411 Black Pinch Rd, Cootharaba, Queensland
Lot 1 on SP296286
Revision 1
November 2021
Prepared by
Ecological Natural Area Management
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Ecological Natural Area Management
Document details
Author details
The author of this bushfire risk assessment and bushfire risk management plan is Adrian Hansen,
proprietor of Ecological Natural Area Management. Note that the author is a Fire Protection
Association of Australia Accredited Practitioner Level 3 in Bushfire Planning and Design. See
Appendix 3 for demonstration that the author is a “professional who is suitably qualified and
experienced with technical expertise in the field of bushfire hazard identification and mitigation,
including protection of biodiversity values”.
Contact details
Adrian Hansen
Ecological Natural Area Management
0400 132 634
[email protected]
Document history
Revision Date Reviewed
Revision 1 04 December 2021_ Adrian Hansen
Document certification
04 December 2021……………
Adrian Hansen Date
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Table of Contents
1 Executive Summary.................................................................................................................................... 5
2 Introduction................................................................................................................................................. 7
2.1 The reasons for the Bushfire Risk Assessment and Management Plan............................................7
2.2 Commissioning of the Bushfire Risk Assessment and Management Plan........................................7
2.3 The aim of the Bushfire Risk Assessment and Management Plan....................................................7
2.4 Legislative considerations................................................................................................................. 7
2.5 Other regulatory considerations........................................................................................................ 7
3 Site description........................................................................................................................................... 8
3.1 Location............................................................................................................................................ 8
3.2 Zoning............................................................................................................................................... 8
3.3 Building Code of Australia building class.......................................................................................... 9
3.4 Applicable development codes......................................................................................................... 9
3.5 Mapped bushfire hazard................................................................................................................... 9
3.6 Topography....................................................................................................................................... 9
3.7 Area of the lot.................................................................................................................................... 9
3.8 Climate.............................................................................................................................................. 9
4 Site vegetation assessment..................................................................................................................... 10
4.1 Site aerial photography................................................................................................................... 10
4.2 Mapped Remnant Regional Ecosystems........................................................................................ 11
4.3 Visually assessed vegetation communities – terrestrial photography.............................................12
4.4 Map of visually assessed vegetation communities.........................................................................13
5 Conservation significance of the vegetation.......................................................................................... 14
5.1 Conservation significance of the vegetation from Queensland Vegetation Management Act..........14
5.2 Conservation significance of the vegetation from the The Noosa Plan...........................................14
6 Bushfire risk assessment........................................................................................................................ 15
6.1 Assessment of bushfire prone area................................................................................................ 15
7 Assessment of the Bushfire Attack Level...............................................................................................15
7.1 Assessment of the Bushfire Attack Level: Methodology..................................................................15
7.2 Modelled bushfire attacks............................................................................................................... 16
7.3 Assessment of fuel loads................................................................................................................ 16
7.4 Forest Fire Danger Index................................................................................................................ 16
7.5 Parameters used in the bushfire behaviour modelling....................................................................16
7.6 Results of bushfire attack modelling...............................................................................................17
7.7 Bushfire Attack Levels for each building elevation..........................................................................17
7.8 Assessment of vegetation clearing.................................................................................................17
8 Bushfire risk management solutions and recommendations...............................................................18
8.1 Bushfire hazard mitigation recommendations: Considerations.......................................................18
8.2 Recommendations for the Noosa Plan Bushfire Overlay Code......................................................18
8.3 Recommendations for Australian Standard AS3959.......................................................................18
8.4 Recommendations for siting and landscaping................................................................................19
8.5 Recommendations for lodgement points for burning debris............................................................19
8.6 Recommendations for on-going management of buildings and landscaping..................................20
8.7 Recommendations for Part E: Natural hazards of the Queensland State Planning Policy 2017.....20
9 References................................................................................................................................................ 21
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10 Appendices.............................................................................................................................................. 22
10.1 Appendix 1: Regional Ecosystem full descriptions........................................................................22
10.2 Appendix 2: Printout reports from the bushfire behaviour modelling software..............................23
10.3 Appendix 3: Qualifications and experience of the author..............................................................25
10.4 Appendix 4: The fire run paper by Tan (2006)...............................................................................26
List of Figures
Figure 1: Proposed site plan ............................................................................................................................ 8
Figure 2: Excerpt from The Noosa Plan Bushfire Overlay showing the house in a Potential Bushfire Impact
Buffer area........................................................................................................................................................ 9
Figure 3: Drone aerial photography acquired on 14 November 2021 showing the native forest vegetation, lot
configuration, rural residential areas, 5m contour lines and mapped watercourses........................................10
Figure 4: Map of the Queensland Vegetation Management Act conservation status of the mapped Regional
Ecosystems near the house............................................................................................................................ 11
Figure 5: View north of the house showing a cleared separation to forest vegetation confirmed as Notophyll
Vine Forest (rainforest)................................................................................................................................... 12
Figure 6: View west of the house showing a cleared separation to forest vegetation confirmed as Notophyll
Vine Forest (rainforest)................................................................................................................................... 12
Figure 7: View south of the house showing a cleared separation to forest vegetation confirmed as Notophyll
Vine Forest (rainforest)................................................................................................................................... 12
Figure 8: Map of the locations of the visually assessed vegetation ...............................................................13
Figure 9: Excerpt from The Noosa Plan Biodiversity Overlay showing the areas near the house with
Conservation Significance or MSES values.................................................................................................... 14
Figure 10: Map showing the modelled bushfire attacks..................................................................................16
Figure 11: Methodologies for minimising the lodgement points for burning debris around the house.............19
List of Tables
Table 1: Regional Ecosystems near the house............................................................................................... 11
Table 2: Conservation significance of the Remnant Regional Ecosystems near the house............................14
Table 3: Assessed Bushfire Attack Levels for the modelled bushfire attacks..................................................17
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1 Executive Summary
A house to be established at 411 Black Pinch Rd, Cootharaba, Queensland in the Noosa Council
jurisdiction is mapped in a Potential Bushfire Impact Buffer area on The Noosa Plan Bushfire Overlay
and Queensland Potential Bushfire Intensity mapping. Therefore, the house is deemed to potentially
be in a Bushfire Prone Area and an assessment of the bushfire risk to the building and a bushfire risk
management plan is required.
Assessment of Bushfire Prone Area
As the house is mapped in a Potential Bushfire Impact Buffer area on The Noosa Plan Bushfire
Overlay and Queensland Potential Bushfire Intensity mapping:
• The house is deemed to be in a Bushfire Prone Area.
As the the house is in a Bushfire Prone Area, an assessment of the Bushfire Attack Level using
Australian Standard AS3959 Construction of buildings in bushfire prone areas is required to be
conducted as specified by the Queensland Building Act and the bushfire requirements of the
National Construction Code.
Assessment of the Bushfire Attack Level
The Bushfire Attack Level (BAL) for the house using Method 2 of Australian Standard AS3959
Construction of buildings in bushfire prone areas was assessed as:
• BAL 12.5 for all building elevations.
Assessment of vegetation clearing
• No clearing of vegetation with conservation significance is required for bushfire risk
mitigation in this plan
Recommendations
Recommendations for the Noosa Plan Bushfire Overlay Code
As the house location is in a Potential bushfire Impact Buffer area, it is recommended that:
• The house is sited in a low hazard area in the lot and achieves a setback of 10 metres from
any retained vegetation.
As the house location is in a Potential bushfire Impact Buffer area and a reliable reticulated water
supply is not available,
It is recommended that:
• The premises to have a minimum water supply capacity of 5,000 litres dedicated for fire
fighting purposes which is sourced from a separate tank, a reserve section in the bottom
part of the main water supply tank, a swimming pool installed immediately upon
construction or a permanent dam.
Recommendations for Australian Standard AS3959
Australian Standard AS3959 Construction of buildings in bushfire-prone areas specifies Deemed to
Satisfy bushfire resistant methodologies based on the assessed Bushfire Attack Level.
It is recommended that:
• The building solution for all building elevations to address the Deemed to Satisfy
requirements of Sections 3 and 5 of Australian Standard AS3959-2018 Construction of
buildings in bushfire-prone areas.
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Other recommendations for building siting and landscaping
It is recommended that:
• The building to have a bushfire fuel free zone around the house, the building be
constructed with a minimum of lodgement points for burning debris and on-going
maintenance of the building be conducted.
See Sections 8.4, 8.5 and 8.6 of this report.
Recommendations for part E: Natural hazards of the Queensland State Planning Policy 2017
It is recommended that, notwithstanding that the proposed building location is in an area of
Potential Bushfire Hazard:
• The building siting, construction, firefighting resources appropriately mitigates the potential
bushfire Hazard as required by the SPP
• The development does not unduly burden emergency services as there is good access for
firefighting appliances, good fire fighting space, good water supply and contributes only one
extra building in the emergency services area
• The building and the cleared and hard-standing areas decreases the severity of a bushfire
on the lot and therefore does not increase severity of the bushfire Hazard and,
• There will be no hazardous material stored on the lot.
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2 Introduction
2.1 The reasons for the Bushfire Risk Assessment and Management Plan
A house to be established at 411 Black Pinch Rd, Cootharaba, Queensland in the Noosa Council
jurisdiction is mapped in a Potential Bushfire Impact Buffer area on The Noosa Plan Bushfire Overlay
and Queensland Potential Bushfire Intensity mapping. Therefore, the house is deemed to potentially
be in a Bushfire Prone Area and an assessment of the bushfire risk to the building and a bushfire risk
management plan is required.
2.2 Commissioning of the Bushfire Risk Assessment and Management Plan
Ecological Natural Area Management has been commissioned to prepare a Bushfire Risk
Assessment and Bushfire Risk Management Plan to fulfil the above requirements. See Appendix 3
for demonstration that the author is a “qualified and experienced consultant with appropriate and
proven technical expertise in the preparation of bushfire hazard assessment reports and
management plans”.
2.3 The aim of the Bushfire Risk Assessment and Management Plan
The aim of this bushfire impact assessment report is to achieve appropriate levels of bushfire
protection for the developed properties while maintaining ecological sustainability.
Bushfire protection for buildings in bushfire prone areas is best achieved using a mix of:
•Fire resistant building technologies in the structures.
•Fire resistant methodologies in the structures such as minimising ember lodgement points
•Providing and appropriate fire break between the developed properties and flammable
vegetation.
• Appropriate building siting for bushfire protection
• Fuel management in the flammable vegetation near the developed properties while
maintaining ecological values of the vegetation habitat.
• Fuel management between the flammable vegetation and the developed properties.
• Maintenance of ecological and habitat values of any vegetation subject to vegetation
management for bushfire risk management.
To achieve the aim, the Plan will conduct bushfire assessments against the applicable legislative
requirements and make recommendations that address the requirements of these legislation.
2.4 Legislative considerations
• Queensland Planning Act,
• Queensland Vegetation Management Act,
• Queensland Building Act
• Queensland State Planning Policy 2017 and,
• The Noosa Plan 2020
2.5 Other regulatory considerations
• The National Construction Code of Australia and
• Australian Standard AS 3959-2018 Construction of buildings in bushfire-prone areas.
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3 Site description
3.1 Location
The site, described as Lot 1 on SP296286 is at 411 Black Pinch Rd, Cootharaba, Queensland in
the Noosa Council jurisdiction. The development is a dwelling house.
Figure 1: Proposed site plan
3.2 Zoning
The lot is zoned as Rural Zone on The Noosa Plan Zone map.
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3.3 Building Code of Australia building class
The building is a Class 1a building under the National Construction Code.
3.4 Applicable development codes
Development codes addressed in this report are:
• The Noosa Plan Bushfire Overlay Code.
3.5 Mapped bushfire hazard
The location of house is mapped as:
• Potential Bushfire Impact Buffer on The Noosa Plan Bushfire Overlay and
• Potential Bushfire Impact Buffer on Queensland potential bushfire intensity mapping.
Figure 2: Excerpt from The Noosa Plan Bushfire Overlay showing the house in a
Potential Bushfire Impact Buffer area
3.6 Topography
Site topography is “Steep hills”: 20% to 30% slope.
3.7 Area of the lot
The Lot area = 11.1 ha
3.8 Climate
The climate is subtropical. That is, the area is influenced by monsoonal climate systems in summer
but also from temperate climate systems in winter. Mean rainfall is approximately 1500.mm per
year. (Bureau of Meteorology, 2004) The “wet” season runs from December to April.
Severe bushfire weather can occur. This is characterised by dry windy days, winds north to north
west for 2-4 days and temperatures 350C or over. These conditions occur from September to
December; worst month, November. (Webster J, 2000)
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4 Site vegetation assessment
4.1 Site aerial photography
Drone aerial photography acquired on 14 November 2021 shows areas of native forest near the
house which is in a rural residential area.
Figure 3: Drone aerial photography acquired on 14 November 2021 showing the native forest vegetation, lot
configuration, rural residential areas, 5m contour lines and mapped watercourses
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4.2 Mapped Remnant Regional Ecosystems
Some of the forest vegetation near the house is mapped as Remnant Regional Ecosystems. The
map of Remnant Vegetation will be used as an aid to identifying the vegetation.
Figure 4: Map of the Queensland Vegetation Management Act conservation status of the mapped Regional
Ecosystems near the house.
Table 1: Regional Ecosystems near the house
Regional Ecosystem Description
RE 12.11.10 Notophyll vine forest +/- Araucaria cunninghamii on metamorphics +/-
interbedded volcanics
(Source: Department of Environment and Heritage Protection, 2021)
See Appendix 1 for the full descriptions of these Regional Ecosystems
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4.3 Visually assessed vegetation communities – terrestrial photography
Terrestrial photography of the vegetation shown below confirms that the forest vegetation near the
house is Notophyll Vine Forest (rainforest).
Figure 5: View north of the house showing a cleared
separation to forest vegetation confirmed as Notophyll
Vine Forest (rainforest)
Figure 6: View west of the house showing a cleared
separation to forest vegetation confirmed as Figure 7: View south of the house showing a cleared
Notophyll Vine Forest (rainforest) separation to forest vegetation confirmed as Notophyll
Vine Forest (rainforest)
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4.4 Map of visually assessed vegetation communities
Based on the visual assessment of the vegetation, inspection of aerial photography, assessment of
vegetation mapping and field verification, the map below shows the locations of the visually
assessed vegetation. The visually assessed vegetation is:
• Rural residential areas and
• Norophyll Vine Forest (Rainforest) - Canopy height = 15 m.
Figure 8: Map of the locations of the visually assessed vegetation
This visually assessed vegetation will be used for subsequent bushfire risk assessments in this
report.
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5 Conservation significance of the vegetation
5.1 Conservation significance of the vegetation from Queensland Vegetation
Management Act
Some of the vegetation near the house derives enhanced conservation significance from the
Queensland Vegetation Act as it is mapped as Remnant Regional Ecosystem. See Figure 4 of this
report for the map showing the areas in the lot mapped as Remnant Regional Ecosystem.
Table 2: Conservation significance of the Remnant Regional Ecosystems near the house
Regional Regional Ecosystem short description VMA conservation VMA biodiversity
Ecosystem class status
RE 12.11.10 Notophyll vine forest +/- Araucaria cunninghamii on Least concern No concern at
metamorphics +/- interbedded volcanics present
5.2 Conservation significance of the vegetation from the The Noosa Plan
Some of the vegetation near the house derives enhanced conservation significance from The
Noosa Plan 2020 Biodiversity Overlay as it is mapped as:
• An Area of Biodiversity Significance and
• MSES Environmental Values
Figure 9: Excerpt from The Noosa Plan Biodiversity Overlay showing the
areas near the house with Conservation Significance or MSES values
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6 Bushfire risk assessment
As the house is mapped in a Potential Bushfire Impact Buffer area on the Noosa Plan Bushfire
hazard Overlay Map and Queensland Potential Bushfire Intensity mapping, this report will detail
bushfire hazard assessments for:
• The Noosa Plan,
• Australian Standard AS 3959 Construction of buildings in bushfire prone areas as
referenced by the National Construction Code of Australia and
• Queensland State Planning Policy 2017.
6.1 Assessment of bushfire prone area
As the house is mapped in a Potential Bushfire Impact Buffer area on The Noosa Plan Bushfire
Overlay and Queensland Potential Bushfire Intensity mapping:
• The house is deemed to be in a Bushfire Prone Area.
As the the house is in a Bushfire Prone Area, an assessment of the Bushfire Attack Level using
Australian Standard AS3959 Construction of buildings in bushfire prone areas is required to be
conducted as specified by the Queensland Building Act and the bushfire requirements of the
National Construction Code. Such a Bushfire Attack Level assessment is conducted on
subsequent pages of this report.
7 Assessment of the Bushfire Attack Level
7.1 Assessment of the Bushfire Attack Level: Methodology
The National Construction Code of Australia references Australian Standard AS3959 Construction
of buildings in bushfire-prone areas for Deemed to Satisfy building requirements for bushfire risk
management construction of buildings. This section assesses the construction Bushfire Attack
Level (BAL) for the house using Method 2 of Australian Standard AS3959 to determine a level of
construction required to achieve the objective of the Standard which is to “prescribe particular
construction details for buildings to reduce the risk of ignition from a bushfire while the fire front
passes” (Standards Australia, 2018). This report uses software developed by Newcastle Bushfire
Consulting which models the Bushfire Attack Level using Method 2 of Australian Standard AS3959.
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7.2 Modelled bushfire attacks
Two bushfire attacks were modelled using Method 2 of Australian Standard AS 3959: Construction
of buildings in bushfire-prone areas. Bushfire attack parameter attenuation was included in the
bushfire attack modelling due to:
• Constrained fire runs from fragmentation of the vegetation due to residential development.
(A short fire run can be used to attenuate bushfire attack parameters as it has been shown
that it takes a period of time and therefore a fire run distance for a bushfire to reach it full
quasi-steady state rate of spread (Cheney and Gould, 1997). The effect of a reduced
bushfire forward rate of spread on the reduction of assessed bushfire attack parameters
was modelled using the method of Tan (2006).
Figure 10: Map showing the modelled bushfire attacks
7.3 Assessment of fuel loads
The fuel loads used were the “Rainforest” fuel loads from Australian Standard AS 3959 of 10 t/ha
surface fuel and 12 t/ha total fuel.
7.4 Forest Fire Danger Index
This report will use the specified Forest Fire Danger Index of FFDI 52. as required by Bushfire
Resilient Communities - Technical Reference Guide for the State Planning Policy State Interest
‘Natural Hazards, Risk and Resilience – Bushfire (QFES, 2019).
7.5 Parameters used in the bushfire behaviour modelling
South bushfire attack
This modelled fire burns up-slope through Notophyll Vine Forest to attack from the south.
• Fuel loads used are the “Rainforest” fuel loads of Australian Standard AS3959 of 10t/ha
surface fuel & 125t/ha total fuel.
• Separation of the house from the hazard: 30m
• Slope in the vegetation = 13.70
• Site slope = 10.70
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North bushfire attack
This modelled fire burns up-slope through Notophyll Vine Forest to attack from the north.
• Fuel loads used are the “Rainforest” fuel loads of Australian Standard AS3959 of 10t/ha
surface fuel & 125t/ha total fuel.
• Separation of the house from the hazard: 17m
• Slope in the vegetation = 13.50
• Site slope = 12.50
• Fire run = 500m leading to a 0.78 reduction of the bushfire rate of spread from the full
quasi-steady state ROS
7.6 Results of bushfire attack modelling
Table 3: Assessed Bushfire Attack Levels for the modelled bushfire attacks
Modelled bushfire attack
Modelled bushfire parameter South bushfire attack North bushfire attack
Separation from the hazard 30 m 23 m
Vegetation Rainforest Rainforest
Modelled surface fuel load 10 t/ha 10 t/ha
Modelled total fuel load 12 t/ha 12 t/ha
Vegetation slope (degrees) 13.7 0 13.5 0
Site slope (degrees) 10.7 0 12.5 0
Fire run >1000 m run 500 m run
Proportion of QSS ROS 1.00 0.78
QSS ROS 1.61 km/h 1.58 km/h
Modelled rate of spread 1.61 km/h 1.23 km/h
Flame width 100 m 100 m
Radiant heat 11.14 kW/m 2 12.14 kW/m 2
Modelled fire line intensity 9957 kW/m 7626 kW/m
Modelled flame length 11.88 m 9.44 m
Level of construction (BAL) BAL 12.5 BAL 12.5
From above the worst case Bushfire Attack Level from the bushfire behaviour modelling is BAL 12.5
See Appendix 2 for a detailed software reports from which the above table was generated.
7.7 Bushfire Attack Levels for each building elevation
Australian Standard AS3959 Construction of buildings in bushfire-prone areas specifies that the
building elevation opposite the assessed bushfire attack direction can be reduced on BAL level due
to shielding by the building but BAL 12.5 cannot be reduced further so the Bushfire Attack Levels
for each of the building elevations are:
• BAL 12.5 for all building elevation.
7.8 Assessment of vegetation clearing
No clearing of vegetation with conservation significance is required for bushfire risk mitigation in
this plan
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8 Bushfire risk management solutions and recommendations
8.1 Bushfire hazard mitigation recommendations: Considerations
As shown above, the house:
• Is in a Potential Bushfire Impact Buffer area on The Noosa Plan Bushfire Overlay,
• Is in a Potential Bushfire Impact Buffer area on Queensland potential bushfire intensity
mapping,
• Is confirmed as being in a Bushfire Prone Area and
• Is assessed as with a construction requirement of BAL 12.5 for all building elevations.
Accordingly, this section will recommend bushfire mitigation requirements for the above
assessments with reference to legislative requirements detailed in:
• The Noosa Plan Bushfire Overlay Code,
• Australian Standard AS 3959 Construction of Buildings in Bushfire Prone Areas and
• State Planning Policy 2017.
8.2 Recommendations for the Noosa Plan Bushfire Overlay Code
As the house is in a Potential Bushfire Impact Buffer area, it is recommended that:
• The house to be sited in a low hazard area in the lot and achieves a setback of 10 metres
from any retained vegetation.
As the house location is in a Potential bushfire Impact Buffer area and a reliable reticulated water
supply is not available,
It is recommended that:
• The premises to have a minimum water supply capacity of 5,000 litres dedicated for fire
fighting purposes which is sourced from a separate tank, a reserve section in the bottom
part of the main water supply tank, a swimming pool installed immediately upon
construction or a permanent dam.
8.3 Recommendations for Australian Standard AS3959
Australian Standard AS3959 Construction of buildings in bushfire-prone areas specifies Deemed to
Satisfy bushfire resistant methodologies based on the assessed Bushfire Attack Level.
It is recommended that:
• The building solution for all building elevations to address the Deemed to Satisfy
requirements of Sections 3 and 5 of Australian Standard AS3959-2018 Construction of
buildings in bushfire-prone areas.
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8.4 Recommendations for siting and landscaping
It is recommended that:the building to have a bushfire fuel free zone around the house. The fuel
free zone to have no overhanging tree branches that can:
• Break off in the high winds associated with bushfire weather and damage property or cause
injury to residents or fire fighting personnel
• Be a lodgement point for wind blown burning debris from the fire front which can then drop
burning debris onto the buildings
It is further recommended that landscaping around the building such as planting low, fire resistant
shrubs or building permanent barriers such as low stone or masonry walls to:
• Create barriers which slow down and cool the fire front.
Such methodologies help to protect buildings from possible attack by burning debris, heat radiation
and direct flame contact.
8.5 Recommendations for lodgement points for burning debris
The Queensland Fire and Rescue Service recommend that buildings be constructed with a
minimum of lodgement points for burning debris.
Figure 11: Methodologies for minimising the lodgement points for burning debris around the house
(Source: Queensland Government, 2000)
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8.6 Recommendations for on-going management of buildings and landscaping
On-going maintenance procedures will ensure that the buildings will maintain the highest levels of
bushfire protection afforded by the siting, landscaping and construction recommendations in this
report. Maintenance strategies include:
Cleaning the roof and gutters of all flammable material on a regular basis, especially in the lead up
to the fire season
• Keeping the lawn buffer zone mown and watered
• Keeping the lawn buffer zone clear of all flammable material
• Clearing away any flammable material lodged against the structure
• Repairing and close any exposed lodgement points for burning debris
• Ensuring all painted surfaces are in good condition
• Maintaining drive ways
• Maintaining screens in good condition
• Maintaining roof in good condition
• Maintaining doors in good condition
• Keeping flammable material away from the buildings
8.7 Recommendations for Part E: Natural hazards of the Queensland State
Planning Policy 2017
It is recommended that, notwithstanding that the proposed building location is in an area of
Potential Bushfire Hazard:
• The building siting, construction, firefighting resources etc appropriately mitigates the
potential bushfire Hazard as required by the SPP
• The development does not unduly burden emergency services as there is good access for
firefighting appliances, good fire fighting space, good water supply and contributes only one
extra building in the emergency services area
• The building and the cleared and hard-standing areas decreases the severity of a bushfire
on the lot and therefore does not increase severity of the bushfire Hazard and,
• There will be no hazardous material stored on the lot.
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9 References
Cheney, N.P. and Gould, J.S. (1997). Letter to the editor – fire growth and acceleration.
International Journal Wildland Fire 7(1):1-5
Couch, P, (2010). The Urban Fringe Under Pressure, in Proceedings of Fire Australia 2010, Fire
Protection association of Australia, Melbourne.
Department of Environment and Heritage Protection, (2020). Regional ecosystem descriptions.
Available from http://www.ehp.qld.gov.au/ecosystems/biodiversity/regional-ecosystems, accessed
November 2021.
Department of Environment and Heritage Protection, (2020). Regional Ecosystem Maps /
Regrowth Vegetation Maps and PMAVs, Available from
<http://www.ehp.qld.gov.au/ecosystems/biodiversity/regional-ecosystems/maps/index.php>,
accessed November 2021.
McCarthy, GJ, Tolhurst, KG & Chatto K, (1999), Overall Fuel Hazard Guide: 3rd Edition,
Department of Natural Resources and Environment, Victoria
NSW Rural Fire Service, (2015). Short fire run: a risk perspective for the bushland interface.
Policy document on bushfire behaviour affected by constrained fire runs. NSW Rural Fire Service,
Sydney.
Queensland Government, (1994). Queensland Vegetation Management Act 2003, The Office of
the Queensland Parliamentary Counsel, Brisbane, Queensland
Queensland Government, (2000). Protecting your home against bushfire attack, Queensland
Government
Queensland Government, (2017). State planning policy 2017 guideline. Department of Local
Government and Planning, Brisbane
Standards Australia, (2018). Australian Standard AS 3959: Construction of buildings in bushfire-
prone areas, Standards Australia, Sydney
Noosa Council, (2020). The Noosa Plan, Noosa Council, Tewantin, Queensland.
Tan, Z, (2006). Effect of fire run distance on bushfire behaviour and its implications for bushfire
hazard rating and prescription of asset protection zones, NSW Rural Fire Service Technical Paper
002/2006, NSW Rural Fire Service, Sydney.
Webster J, (2000). The complete bushfire safety book, Random House Australia Pty Ltd, Milsons
Point, NSW
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Ecological Natural Area Management
10 Appendices
10.1 Appendix 1: Regional Ecosystem full descriptions
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10.2 Appendix 2: Printout reports from the bushfire behaviour modelling software
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This report uses a reduced bushfire rate of spread due to a reduced fire run. See Sections 7.2 and
7.5 of this report.
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10.3 Appendix 3: Qualifications and experience of the author
This appendix to demonstrate that the author is an “appropriately qualified and experienced
consultant with appropriate and proven technical expertise in the preparation of bushfire hazard
assessment reports and management plans” (Sunshine Coast Regional Council, 2014b).
Author: Adrian Hansen
Relevant qualifications:
• Master of Environmental Management (with Distinction)
• Graduate Diploma in Design for Bushfire Prone Areas
• Diploma in Community Natural Resource Management
• Certificate IV Applied Environmental Management
• Certificate II in Bush Regeneration (with Distinction)
Relevant certifications:
• FPAA Accredited Practitioner Level 3 in Bushfire Planning and Design.
(See FPAA website (http://www.fpaa.com.au/bpad.aspx) for details of the certification)
Other relevant qualifications
• Certificate II in Public Safety (Fire fighting Operations)
• Certificate in Bushfire Management
• Certificates in Fire Fighting - Advanced skills & Crew leadership
• Certificate in Property Fire Management Planning
• Certificate in Fire and Biodiversity Monitoring
• Certificate in Regional Ecosystems Frameworks
• Bachelor of Applied Science (Majors in botany and ecology)
Relevant experience:
• 12 years experience preparing bushfire risk assessments and bushfire risk management
plans (Plans have included individual lots, sub-divisions, eco-cabins developments, schools
etc including both deemed to satisfy and alternate solutions)
• 13 years experience in bush fire fighting
• 13 years experience in bushfire ecology (includes fire and biodiversity monitoring and
ecological fire management plans for conservation areas)
• 14 years experience in natural resource management, ecology, ecological restoration,
environmental management planning etc
Bushfire Risk Assessment and Management Plan for a house at 411 Black Pinch Rd, Cootharaba December 2021
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10.4 Appendix 4: The fire run paper by Tan (2006)
As the paper by Tan (2006): Effect of fire run distance on bushfire behaviour and its implications
for bushfire hazard rating and prescription of asset protection zones, is an unpublished document
held be the NSW Rural Fire Service, this appendix is a full printout of the paper.
EFFECT OF FIRE RUN DISTANCE ON BUSHFIRE BEHAVIOUR
AND ITS IMPLICATIONS FOR BUSHFIRE HAZARD RATING AND
PRESCRIPTION OF ASSET PROTECTION ZONES
Technical Paper 002/2006
By Dr Zhenxiang Tan
RISK MANAGEMENT PERFORMANCE
9 March 2006
Bushfire Risk Assessment and Management Plan for a house at 411 Black Pinch Rd, Cootharaba December 2021
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EFFECT OF FIRE RUN DISTANCE ON BUSHFIRE
BEHAVIOUR AND ITS IMPLICATIONS FOR BUSHFIRE
HAZARD RATING AND PRESCRIPTION OF ASSET
PROTECTION ZONES
By Dr Zhenxiang Tan
1. Introduction
In Australia, the bushfire behaviour prediction system used by Australian land
management/fire agencies is based on McArthur Fire Danger Meter (McArthur 1973)
developed on the basis of over 5000 documented wildfires and 500 prescribed fires
(Chandler et al. 1983). Potential fire behaviour is predicted from fire danger ratings
derived from meteorological data (McArthur 1966, 1967, Noble et al. 1980, Luke and
McArthur 1978). The predicted behaviour by the meter is only for quasi-steady or
established fires with no provision for initiating fire behaviour. Therefore the potential
bushfire behaviour based on the meter may be over-predicted in the case of an
unestablished bush fire. The hazard ratings and the prescribed widths of asset
protection zones based on the over predicted bushfire behaviour will then be over
estimated in such a case. In order to rate bushfire hazard or prescribe APZs properly,
it needs to determine whether a block of bushfire prone land will allow for a fire to
develop to a quasi-steady state or not and take the effect of an unsteady fire on hazard
rating or APZ prescription into account accordingly.
In theory, a bushfire will eventually develop to a quasi-steady state if the distance of fire
run is long enough. This means that there must exist a relationship between bushfire
belabour and fire run distance. This paper is aimed to establish such a relationship and
analyse the implications for rating bushfire hazard and prescribing APZs. To do this, a
theoretical model developed by Cheney and Barry (1969) for predicting the rate of fire
spread at its early stage has been used to derive the corresponding equation of fire run
distance. Based on these equations, an approach for predicting the effect of fire run
distance on rate of fire spread has been established and the resultant implications for
rating bushfire hazard and prescribing APZs have also been studied.
2. Mathematical Model
It has been identified that bush fires from a point source ignition increase their spread
rates as they grow and eventually develop to the so-called quasi-steady state. The
equation predicting fire growth in forest fires given by Cheney and Barry (1969) was:
R = Rss e-a/t ……(1)
Where
R = rate of spread at time t
Rss= equilibrium spread rate
t = elapsed time since ignition
a is a constant.
The integrated form of Equation (1) is:
t t
S= R
0
SS e -a/t dt =Rss 0
e -a/t dt ……(2)
Where
S = fire run distance
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Equation (1) and Equation (2) can be used in two different ways. Firstly, it can be used
to predict the rate of fire spread at a given time and the resultant fire run distance up to
this point of time. Secondly, they can be used to estimate the maximum rate of fire
spread which can be reached for a given fire run distance. As shown in Equation (1)
and (2), the use of them requires the constant a. This constant value depends on the
time which a fire requires to develop to a quasi-steady state. The required time for a
point ignition fire under fairly stable fuel moisture and wind conditions is in 20 – 30
minutes (Luke and McArthur 1978). According to Cheney and Gould (1997), the more
frequently the direction of wind switches the shorter a fire will take to reach its quasi-
steady state. With respect to the magnitude of wind, the opposite is true. In addition,
fire intensity also influences how soon a fire can reach its quasi-steady state. Low
intensity fires tend to reach its quasi-steady state faster than high intensity fires
(McAlpine and Wakimoto 1991). Cheney and Gould (1995) found that low intensity
grass and woodland fires lit from point sources reached their maximum rate of spread
in 5-10 minutes while medium to high intensity fires in winds above 4m/s took 12 -45
minutes. In some circumstances, it may take many hours for high intensity forest fires
to reach a quasi-steady state.
Considering the time which a fire reaches a quasi-steady state is highly variable, the
value of constant a in Equation (1) and (2) also varies within a certain range. In order to
obtain meaningful predictions with these equations, a proper value of constant a needs
to be used according to the expected fire scenarios such as fast growth fires, medium
fast growth fires and slow growth fires. If the times for fast growth fires, medium fast
growth fires and slow growth fires develop to 90% of their quasi-steady rate of spread
are assumed to be 10 minutes, 30 minutes and 60 minutes respectively, then the
corresponding values of constant a can be determined by using Equation (1) being
1.05, 3.16 and 6.32 respectively. Therefore, the variants of Equations (1) and (2) for
the three different fire scenarios are:
(1) Fast growth fires
R = Rss e-1.05/t ……(3)
t
e
-1.05/t
S=Rss dt ……(4)
0
(2) Medium fast growth fires
R = Rss e-3.16/t ……(5)
t
e
-3.16/t
S=Rss dt ……(6)
0
(3) Slow growth fires
R = Rss e-6.32/t ……(7)
t
e
- 6.32/t
S = Rss dt ……(8)
0
The relative rate of spread for a given time for a given fire scenario can then be directly
predicted by utilising the analytical equations or the graphic forms of these equations
shown in Figure 1. For instance, the relative rate of spread at time = 30 minutes for
fast, medium and slow growth fires are determined to be 0.96, 0.90 and 0.81
respectively in accordance with Figure 1.
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1.00
0.90
Relative Rate of Spread (R/Rss)
0.80
0.70
0.60
0.50 Fas t
Medium Fas t
0.40
Slow
0.30
0.20
0.10
0.00
0 5 10 15 20 25 30 35 40 45 50 55 60
Elapsed Time (min)
Figure 1. Graphic Formats of Equations (3), (5) and (7)
To predict the actual rate of fire spread for a given time or the fire run distance up to
this point of time, the quasi-steady rate of fire spread R ss needs to be determined first.
For forest and woodlands, the rate of spread equation derived from McArthur meter
can be used for this purpose and its mathematical expression is (Nobel et al. 1980):
Rss= 0.0012 FFDI w e0.069θ ……(9)
Where
Rss = quasi-steady rate of fire spread (km/h)
FFDI = Forest Fire Danger Index
w= fine fuel load (t/ha)
θ = slope (degrees)
For FFDI =80, w=25 t/ha and θ =0, R ss will take a value of 2.4 km/h which is equivalent
to 40 m/min. Therefore, the actual rates of spread will be 38, 35 and 30 m/min at time
=30 minutes after a point ignition for the above three fire scenarios. The fire run
distances can also be determined by doing numerical integrations of the fire run
distance equations or using the curves shown in Figure 2.
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2000
1800
1600
Fire Run Distance (m)
1400
1200
1000
800 Fas t
600 Medium Fas t
Slow
400
200
0
0 5 10 15 20 25 30 35 40 45 50 55 60
Elapsed Time (min)
Figure 2. Graphic Formats of Equations (4), (6) and (8)
In addition, one can predict the relative rate of spread for a given fire run distance by
utilizing the flowing two step approach:
(1) Estimate the elapsed time corresponding to a given fire run distance by performing
iterative calculations with Equation (2) or its graphic format (Figure 2);
(2) Determine the relative rate of spread corresponding to the estimated time by using
the Equation (1) or its graphic format (Figure 1).
For instance, the times corresponding to fire run distances of 100m, 200m, 300m,
400m and 500m are determined to be 4.6 minutes, 7.6 minutes, 10.4 minutes, 13.2
minutes and 15.8 minutes for a fast growth fire in accordance with Figure 2. The
relative rate of spread corresponding to these fire run distances are then be determined
being 0.795, 0.871, 0.904, 0.923 and 0.935 for the same type of fire in accordance
with Figure 1.
By applying the approach described above, the direct relationship between fire run
distance and relative rate of spread can then be established. The curves shown in
Figure 3 is the graphic representation of the relationship between fire run distance and
relative rate of spread under the three different fire growth scenarios. With this graph,
the relative rate of spread can be directly determined for a given fire run distance under
a given fire scenario. For instance, for a block of bushfire prone land with a maximum
fire run distance of 300m the maximum relative rates of fire spread for a fire within this
block of land are determined to be 0.90, 0.80 and 0.70 respectively for fast, medium
and slow growth fires.
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1.0
0.9
0.8
Relative Rate of Spread (R/Rss)
0.7
0.6 Fast
Medium
0.5
Slow
0.4
0.3
0.2
0.1
0.0
Fire Run Distance (m)
Figure 3. Relative Rate of Spread and Fire Run Distance
3. Implication for Rating Bushfire Hazard
Fire run distance influences the rate of fire spread and therefore fire hazard. The
hazard associated with a given vegetation type is usually measured by fire intensity
which is expressed by (Byram 1959):
I = H W R/36 ……(10)
Where
I = fire intensity (kW/m)
H= heat yield of the fuel, fuel related constant
W = Available fuel load (tonnes/hectare)
R = Rate of spread (km/h)
Based on Equation (10), the fire intensities of steady fires and non-steady fires can be
determined by:
I = H W R/36 ……(11)
Iss = H W Rss/36 ……(12)
Divide Equation (11) by Equation (12), we have
I/ Iss =R/Rss ……(13)
Equation (13) suggests that the relative rate of spread is equivalent to the relative
hazard rating for a given fuel type. The relative rate of spread for a given fire run
distance can be predicted with Equation (1) and consequently its implication for hazard
rating. If fire run distance is grouped into the categories of <=50m, 50-100m, 100-
200m, 200-500 and 500-1000m, then the relative hazard rating for a given vegetation
type can be determined for the three different fire scenarios ( See Table 1).
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Table 1 Relative Hazard Ratings of Fire Run Distances
Relative Hazard Rating
Fire Run Distance (m) Medium growth
Fast growth fire Slow growth fire
fire
<=50 0.42 0.25 0.18
50-100 0.75 0.59 0.47
100-200 0.84 0.70 0.59
200-500 0.91 0.81 0.72
500-1000 0.95 0.89 0.82
The relative hazard ratings shown in Table 1 can be used to quantify the effect of fire
run distance on overall hazard level by factoring the overall hazard index/score by a
corresponding relative rating of a give fire run distance. By doing so, the potential over
- prediction of hazard level for a block of bushfire prone land with a small fire run
distance can be avoided and therefore more cost-effective mitigation measures can be
chosen and implemented.
4. Implication for Prescribing APZs
The objective of APZs is to mitigate the impact of bushfire by providing a buffer zone
between a development and surrounding bushfire hazard. Apparently the wider the
APZ prescribed for a site, the less impact the site will be subject to. However, if an
APZ is over prescribed, then developments on the subject site may become more
costly. In view of this, it is necessary to accurately quantify the level of attack from the
bushfire hazard for a given site. To do this, NSW RFS has developed a systematic
methodology which comprises a set of equations (Tan et al. 2005). The principle of the
methodology is to predict the potential bushfire behaviour and the resultant radiant heat
flux to which a site at a given distance from fire front may be exposed. With the NSW
RFS methodology, the required minium width of APZ can be determined by finding the
distance at which the maximum radiant heat flux to which the subject site may be
exposed is equal to the predefined radiant heat flux threshold.
The rate of fire spread equation used in the methodology predicts the quasi-steady rate
of spread and therefore the APZs prescribed by using this methodology might be more
than adequate in the cases of bushfire prone lands with small fire run distances. In
order to prescribe cost-effective APZs, it is necessary to take the effect of fire run
distance on bushfire behaviour and the resultant impact into account. This can be
done by incorporating Equation (1) and Equation (2) into the current methodology. For
instance, the APZ for forest under FDI = 80 and slope = 0 degree is determined to be
28 m. when taking fire run distance into account, the corresponding APZs under the
same conditions are determined and shown in Table 2.
As shown in Table 2, the modelled widths of APZs for three different fire scenarios vary
from fire run distance and will tend to be a constant when fire run distances become
large enough. This means that a smaller APZ needs to be prescribed if the maximum
fire run distance is less than a threshold distance. For instance, if the maximum fire
run distance of a block of land covered with forest is 100m, then the corresponding
APZs for fast, medium and slow growth fires will be 24m, 21m and 19m compared with
a APZ of 28m for a steady state fire.
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Table 2 Modelled APZs for forest (FDI=80, Level Ground)
Asset protection Zones (m)
Fire Run Distance (m) Fast Growth Medium Growth Slow Groth
10 16 13 11
20 19 15 13
30 20 17 14
40 21 18 15
50 22 19 16
100 24 21 19
150 25 22 20
200 26 23 21
250 26 24 22
300 26 24 22
350 27 25 23
400 27 25 23
450 27 25 24
500 27 25 24
550 27 26 24
600 28 26 24
650 28 26 25
700 28 26 25
750 28 26 25
800 28 26 25
850 28 26 25
900 28 26 25
950 28 27 25
1000 28 27 25
1500 28 27 26
2000 28 27 27
2500 28 28 27
5000 28 28 28
5. Conclusions
To sum up, the following conclusions can be made:
(1) An approach for predicting the effect of fire run distance on bushfire behaviour has
been developed on the basis of the existing time dependant rate of spread equation
developed by Cheney.
(2) By utilizing the established approach, the implications of fire run distance for rating
bushfire hazard and prescribing APZs have been analysed for different fire
scenarios.
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(3) The analysis results reveal that the bushfire hazard ratings and the APZs for a
given bushfire hazard vary with fire run distances and will become constant when
fire run distance reach a threshold value. This means that it is necessary to take
into fire run distance into account in order to prevent from over rating bushfire
hazard or over prescribing APZs for bushfire prone lands with small fire run
distances.
6. References
Byram GM 1959. Forest fire behaviour. In Forest fire control and use. (Ed. KP Davis),
McGraw – Hill, New York, 90-123 pp.
Chandler, C., et al. 1983. Fire in forestry. Vol. I: Forest fire behaviour and effects. Wiley,
New York.
Cheney, N.P. and Bary, G.A.V. 1969. The propagation of mass conflagration in a
standing eucalyptus forest by the spotting process. Paper 46. In collected papers,
Mass Fire Symposium Volume 1. Commonwealth of Australia, Defence Standard
Laboratories Maribyrnong Victoria, 19pp.
Cheney, N.P. and Gould, J.S. 1997. Letter to the editor – fire growth and acceleration.
International Journal Wildland Fire 7(1):1-5.
Luke, R.H. and McArthur, A.G. 1978. Bushfires in Australia. Australian Government
Publishing Services, Canberra, 359pp.
McArthur, A.G. 1966. Weather and grassland fire behaviour. Forest Research Institute,
Forest and Timber Bureau of Australia, Leaflet no. 100, Canberra.
McArthur, A.G. 1967. Fire behaviour in eucalypt forest. Forest Research Institute,
Forest and Timber Bureau of Australia, Leaflet no. 107, Canberra.
McArthur, A.G. 1973. Forest fire danger meter, Mark V. Forest Research Institute,
Forest and Timber Bureau of Australia, Canberra.
McAlpine, R.S. and Wakimoto, R.H. 1991. Acceleration of a fire from point source to
equilibrium spread. Forest Science 37:1314 -1337.
Noble, I.R., Bary, G.A.V, & Gill, A.M. 1980. McArthur fire danger meters expressed as
equations. Aust. J. Ecol. 5, 201-203.
Zhenxiang Tan, Stuart Midgley and Grahame Douglas 2005. A Computerized Model for
Bushfire Attack Assessment. Paper presented at the Symposium of Planning for
Natural Hazards, Wollongong.