@article {bnh-8361, title = {Determining threshold conditions for extreme fire behaviour - final project report}, year = {2022}, month = {09/2022}, institution = {Bushfire and Natural Hazards CRC}, address = {Melbourne}, abstract = {

In the last decade, there have been extreme wildfire events around the world resulting in substantial social, economic and environmental impacts. They threaten many lives and cost billions of dollars in damage. Climate change is making the fire seasons around the world even worse by extending the number of dry and hot days [1-4]. A longer fire season is expected to result in more frequent and severe fires [5, 6]. Australia{\textquoteright}s bushfire season 2019/20 (Black Summer fires hereafter) appears to have supported these conclusions in terms of the ecological consequences and impacts on human populations [7].

In most cases, these consequences are the result of dynamic fire behaviours (DFBs) [8-11]. The DFBs are localised dynamic events that occur within fires, whereby physical feedbacks greatly enhance fire intensities and rates of spread. Understanding and having the ability to predict DFBs in wildfire events is essential to ensure the safety of communities living in or near the Wildland-Urban Interface.

In this regard, the project {\textquoteleft}Determining threshold conditions for extreme fire behaviour{\textquoteright} was focused on the understanding and analysis of dynamic fire effects; their influence on fire behaviour and structures; and the potential of including these effects in fire behaviour models and new building standards.

}, issn = {735}, author = {Alex Filkov and Thomas Duff and Trent Penman} } @inbook {bnh-8357, title = {Wildland fire}, booktitle = {Handbook of Fire and the Environment }, volume = {The Society of Fire Protection Engineers Series}, year = {2022}, publisher = {Springer}, organization = {Springer}, chapter = {Wildland Fire}, address = {Cham}, abstract = {

Wildfires, and their associated management activities, can have complex social, economic, and environmental impacts. This chapter highlights some of the key impacts of wildfires in six sections. The first section about community focuses on relationships between recent destructive wildfires around the globe and losses to life and property. It also presents the main mechanisms of house loss in the Wildland-Urban Interface. Following that, a section about biodiversity impacts describes the major effects of wildfires and associated fire regimes on plants and animals, underlining both negative and positive effects. Then, the focus shifts to soil and water with a section that highlights how wildfires can have serious implications for downstream water quality and yield, posing a threat to water security for the people and aquatic wildlife. This is followed by a section about air quality, which describes the effect of wildfires on visibility, human health and their contribution to climate change. The next section highlights the role of dynamic fire behaviours that lead to the most severe impacts, describing the fire behaviours themselves and their frequency of occurrence. The chapter closes with a case study describing the extreme impacts of the 2019/2020 fire season in south-eastern Australia on people and the environment.

}, isbn = {978-3-030-94356-1}, doi = {https://doi.org/10.1007/978-3-030-94356-1_7}, url = {https://link.springer.com/chapter/10.1007/978-3-030-94356-1_7}, author = {Alex Filkov and Jane Cawson and Matthew Swan and Trent Penman} } @conference {bnh-8286, title = {Predicting merging fire behaviour in Planned Burning}, booktitle = {AFAC21}, year = {2021}, month = {10/2021}, publisher = {AFAC}, organization = {AFAC}, address = {Online}, abstract = {

It was found that laboratory scale fire experiments do not replicate large scale fires, and therefore, extensive high temporal and spatial resolution experimental data at larger scales are required to fully understand how a given fire will merge and spread. Unmanned aerial vehicles (UAVs or drones) may be a useful tool in obtaining these measurements. To provide operational and management personnel with a better understanding of the dynamic nature of fire line merging, UAVs were used in this study to measure fire rate of spread throughout the burns recording linear fire rates of spread and merging fire rate of spread in a range of fuel types in western Victoria. Using special software, we were able to record the rates of spread over time and determine the effect of ignition patterns on fire behaviour. These utilisation outcomes can be used to better support decision making around ignition methods during planned burning operations, as well as maximising the information available to support firefighter training and further research and development.

}, keywords = {Fire behaviour, fire predictions, UAVs}, url = {https://www.afac.com.au/events/proceedings/05-10-21/article/predicting-merging-fire-behaviour-in-planned-burning}, author = {Alex Filkov} } @article {bnh-7686, title = {Determination of Firebrand Characteristics Using Thermal Videos}, journal = {Fire}, volume = {3}, year = {2020}, month = {11/2020}, abstract = {

Burning firebrands generated by wildland or prescribed fires may lead to the initiation of spot fires and fire escapes. At the present time, there are no methods that provide information on the thermal characteristics and number of such firebrands with high spatial and temporal resolution. A number of algorithms have been developed to detect and track firebrands in field conditions in our previous study; however, each holds particular disadvantages. This work is devoted to the development of new algorithms and their testing and, as such, several laboratory experiments were conducted. Wood pellets, bark, and twigs of pine were used to generate firebrands. An infrared camera (JADE J530SB) was used to obtain the necessary thermal video files. The thermograms were then processed to create an annotated IR video database that was used to test both the detector and the tracker. Following these studies, the analysis showed that the Difference of Gaussians detection algorithm and the Hungarian tracking algorithm upheld the highest level of accuracy and were the easiest to implement. The study also indicated that further development of detection and tracking algorithms using the current approach will not significantly improve their accuracy. As such, convolutional neural networks hold high potential to be used as an alternative approach

}, keywords = {wildfires; firebrands; software; detection; tracking; fire management}, doi = {https://doi.org/10.3390/fire3040068}, url = {https://www.mdpi.com/2571-6255/3/4/68}, author = {Sergey Prohanov and Alex Filkov and D. P. Kasymov and Mikhail Agafontsev and Vladimir Reyno} } @article {bnh-7499, title = {Determining threshold conditions for extreme fire behaviour - annual report 2019-2020}, number = {626}, year = {2020}, month = {11/2020}, institution = {Bushfire and Natural Hazards CRC}, address = {MELBOURNE}, abstract = {

At this phase the project was focused on development of a new method to test flammability of live vegetation in dynamic conditions and understanding influence of climatic changes on the 2019/20 bushfire season in New South Wales (NSW), Victoria, and South Australia (SA).

Understanding live vegetation fuel properties and how they behave when exposed to radiant heat and flame allows us to better predict fire behaviour in forested areas. This study aims to determine a more effective, replicable and accurate method of testing flammability in live vegetation by comparing the impact different radiant heating regimes have on the ignitibility of live vegetation samples. Current methodologies are limited in their ability to provide accurate quantification of flammability due to their reliance on static heat flux exposure, which does not accurately replicate how live plants experience radiative heat flux during a wildfire in their natural environment. Two heating regimes were tested for this study {\textendash} a static heat flux to reflect current methods and a dynamic (increasing) heat flux to more accurately replicate real conditions of an approaching fire front. Piloted-ignition and unpiloted-ignition were also tested for both of these heating regimes. A Variable Heat Flux (VHFlux) Apparatus was used to study flammability of Acacia floribunda, Cassinia arcuata, Pinus radiata and bark from Eucalyptus obliqua. Time to pyrolysis (production of volatile products), smouldering, flaming ignition, complete consumption and radiant exposure (the radiant energy received by a sample over a time of heating, He) were used as ignitability measures. It was observed that time and radiant exposure required to reach flaming ignition (and the other ignitibility metrics) was higher under a dynamic heating regime. It was also observed that the presence of a pilot igniter greatly increased the number of samples that reached flaming ignition, and decreased the time and He required to reach flaming ignition (and the other ignitibility metrics). These results suggest clear differences observed between heating regimes for time and Herequired for ignition and other ignitibility measures, which supports the validity of using dynamic heating regimes and the VHFlux apparatus as a standardised method. Adoption of this methodology is recommended to ensure more realistic data on flammability of individual plant species and plant communities, which will ultimately lead to better informed and more accurate wildfire behaviour modelling.

There is no doubt that the fire season of 2019/20 was extraordinary. A total of 18,983,588hectares were burned, 3113 houses and 33 lives lost in 15,344 bushfires in Black Summer fires. NSW had the highest number of fires, area burned, houses and lives lost for the last 20 years. Two mega-blazes occurred in NSW and burned more than in any fire season during the last 20 years. Victoria had the highest number of fires, area burned, and houses lost (except for the Black Saturday fires). SA had the highest number of houses lost in the last 20 years. Relationships between the burned area and number of fires, the houses and lives lost had positive trend for all states irrespective of the dataset. A negative relationship between the houses and lives lost for SA was the only exception. Multiple studies show that fire weather will become more severe in many regions around the world. Based on this and observed positive trends for all categories for NSW and Victoria, it is likely that the values will continue to increase in these states in the future. SA before 2019/20 was in a relatively good position showing negative trends for almost all categories. However, the 2019/20 fire season changed that for the worse. The magnitude of effect from increased fire weather may depend on how these conditions alter vegetation across Australia, however the indications shown in this analysis are concerning for fire managers.

Smoke from bushfires significantly impacted on people with cardiovascular and respiratory problems and increased mortality. It also had indirect impact on the economy by disrupting communities. The total impact of the 2019/20 bushfire season to the economy is estimated to be as much as A$40 billion. Due to the record burned area, at least 1 billion vertebrate animals were lost. It will take many years to restore the economy in impacted areas, and for animal and vegetation biodiversity to recover. Understanding of high-level trends of number of fires, area burned, houses and lives lost for the last two decades in south-eastern Australia will provide useful insights to fire managers for future strategies and policies.

}, keywords = {Behaviour, conditions, extreme fire, threshold}, issn = {626}, author = {Alex Filkov and Thomas Duff and Trent Penman} } @article {bnh-7475, title = {Exploring the key drivers of forest flammability in wet eucalypt forests using expert-derived conceptual models}, journal = {Landscape Ecology}, volume = {35}, year = {2020}, month = {06/2020}, pages = {1775{\textendash}1798}, abstract = {

Context

Fire behaviour research has largely focused on dry ecosystems that burn frequently, with far less attention on wetter forests. Yet, the impacts of fire in wet forests can be high and therefore understanding the drivers of fire in these\ systems\ is vital.

Objectives

We sought to identify and rank by importance the factors plausibly driving flammability in wet eucalypt forests, and describe relationships between them. In doing so, we formulated a set of research priorities.

Methods

Conceptual models of forest flammability in wet eucalypt forests were elicited from 21 fire experts using a combination of elicitation techniques. Forest flammability was defined using fire occurrence and fireline intensity as measures of ignitability and heat release rate, respectively.

Results

There were shared and divergent opinions about the drivers of flammability in wet eucalypt forests. Widely agreed factors were drought, dead fine fuel moisture content, weather and topography. These factors all influence the availability of biomass to burn, albeit their effects and interactions on various dimensions of flammability are poorly understood. Differences between the models related to lesser understood factors (e.g. live and coarse fuel moisture, plant traits, heatwaves) and the links between factors.

Conclusions

By documenting alternative conceptual models, we made shared and divergent opinions explicit about flammability in wet forests. We identified four priority research areas: (1) quantifying drought and fuel moisture thresholds for fire occurrence and intensity, (2) modelling microclimate in dense vegetation and rugged terrain, (3) determining the attributes of live vegetation that influence forest flammability, (4) evaluating fire management strategies.

}, keywords = {Cognitive mapping, Conceptual models, Expert elicitation, Fire behaviour, fire intensity, flammability, Structured decision-making, Structured expert judgement, Wet forest, Wildfire}, doi = {https://doi.org/10.1007/s10980-020-01055-z}, url = {https://link.springer.com/article/10.1007/s10980-020-01055-z}, author = {Jane Cawson and Victoria Hemming and Ackland, A and Wendy R. Anderson and David Bowman and Ross Bradstock and Brown, T and Jamie Burton and Geoffrey J. Cary and Thomas Duff and Alex Filkov and Furlaud, James M. and Tim Gazzard and Kilinc, Musa and Petter Nyman and Ross Peacock and Mike Ryan and Jason J. Sharples and Gary J. Sheridan and Tolhurst, K.G. and Tim Wells and Phil Zylstra and Trent Penman} } @article {bnh-7036, title = {Impact of Australia{\textquoteright}s catastrophic 2019/20 bushfire season on communities and environment. Retrospective analysis and current trends}, journal = {Journal of Safety Science and Resilience}, year = {2020}, month = {07/2020}, abstract = {

2019/20 Australia{\textquoteright}s bushfire season (Black Summer fires) occurred during a period of record breaking temperatures and extremely low rainfall. To understand the impact of these climatic values we conducted a preliminary analysis of the 2019/20 bushfire season and compared it with the fire seasons between March 2000 and March 2020 in the states of New South Wales (NSW), Victoria, and South Australia (SA). Forest and fire management in Australia were asked to provide data on the number of fires, burned area, life and house loss, as well as weather conditions. By March 2020 Black Summer fires burnt almost 19 million hectares, destroyed over 3,000 houses, and killed 33 people. Data showed that they were unprecedented in terms of impact on all areas. A number of mega-fires occurred in NSW resulting in more burned area than in any fire season during the last 20 years. One of them was the largest recorded forest fire in Australian history. Victoria had a season with the highest number of fires, area burned, and second highest numbers of houses lost for the same period. SA had the highest number of houses lost in the last 20 years. Black Summer fires confirmed existing trends of impact categories during the last two decades for NSW and Victoria. It showed that the smoke from the bushfires may be a significant concern in the future for the global community, as it travels to other countries and continents. Based on preliminary data, it will take many years to restore the economy and infrastructure in impacted areas, and to recover animal and vegetation biodiversity.

}, keywords = {2019/20 season, bushfires, Impact, retrospective analysis}, doi = {https://doi.org/10.1016/j.jnlssr.2020.06.009}, url = {https://www.sciencedirect.com/science/article/pii/S2666449620300098}, author = {Alex Filkov and Tuan Ngo and Stuart Matthews and Simeon Telfer and Trent Penman} } @article {bnh-7708, title = {Leaf traits predict global patterns in the structure and flammability of forest litter beds}, journal = {Journal of Ecology}, year = {2020}, month = {12/2020}, abstract = {
  1. Fallen plant material such as leaves, needles and branches form litter beds which strongly influence fire ignition and spread. Traits of the dominant species influence litter flammability directly by determining how individual leaves burn and indirectly through the structure of the litter bed. However, we are yet to determine the relative importance of these different drivers across a range of plant species from different biomes.
  2. We undertook a meta-analysis, combining leaf trait, litter structure and flammability data for 106 species from North America, South America, Europe, Asia and Australia. The dataset encompassed broad-leaved and coniferous species from seven different experimental studies. Relationships between leaf traits, litter structure and key flammability metrics{\textemdash}sustainability, combustibility and consumability{\textemdash}were analysed using bivariate and piecewise structural equation modelling (SEM).
  3. Traits which characterise the three-dimensional nature of the leaf and how much space a leaf occupies showed much stronger associations to litter structure and flammability than other morphological traits. Leaf curl, surface area to volume ratio (SAV) and SLA predominately influence litter flammability indirectly via litter structure with SLA being the only leaf trait which had a negative direct effect on flame duration. Packing ratio and bulk density were influenced by different combinations of leaf traits and, in turn, they aligned with different flammability metrics. Bulk density predicted flame spread rate and flame duration whereas packing ratio predicted consumption.
  4. Synthesis. We identified key leaf and litter traits which influence different components of litter bed flammability. Importantly, we show that the effects of these leaf and litter traits are consistent across a wide range of taxa and biomes. Our study represents a significant step towards developing trait-based models for predicting surface wildfire behaviour. Such models will more flexibly accommodate future shifts in the composition of plant species triggered by altered fire regimes and climate change.
}, keywords = {Fire behaviour, flammability, leaf traits, litter properties, meta-analysis, surface fuel}, doi = {https://doi.org/10.1111/1365-2745.13561}, url = {https://besjournals.onlinelibrary.wiley.com/doi/full/10.1111/1365-2745.13561}, author = {Jamie Burton and Jane Cawson and Alex Filkov and Trent Penman} } @article {bnh-5830, title = {Determining threshold conditions for extreme bushfire behaviour annual report 2018-2019}, number = {508}, year = {2019}, month = {09/2019}, institution = {Bushfire and Natural Hazards CRC}, address = {Melbourne}, abstract = {

Crown fires in forest ecosystems can pose a major threat to life and property due to their high intensities and rapid rates of spread. However, research into the prediction of crown fire dynamics in the Eucalyptus forests of Australia is limited. Previous studies have focused on coarse temporal scales, utilised low resolution weather based predictors, and often disregard the spatial nature of crown fires. Our study aimed to use observations from large wildfires in eucalypt forests to develop an empirical model to predict the likelihood of crown fire events using environmental predictors at an hourly scale. Our study was conducted in south-eastern Australia using data from fifteen large wildfires that occurred between 2009 and 2015. Fire severity maps were created for each fire at a 30\ m resolution using Landsat imagery from which we calculated the proportion of 30 m pixels experiencing crown fire within a 150 x 150 m window (2.25 ha). Predictor variables were chosen to represent the four key environmental drivers of fire behaviour, namely fuel moisture (i.e. live and dead fuel), fuel load and structure (i.e. surface, elevated, and bark fuels, and tree height), fire weather (i.e. vapour-pressure deficit, wind speed, relative wind direction) and topography (i.e. slope and ruggedness). Random Forests were used to model the effect of environmental drivers on the proportion of crown fire. Fuel moisture content variables were the best predictors of probability of crown consumption. Topographic variables and fire weather had only an intermediate influence and fuel load and structure had the lowest influence. Crown fire runs largely occurred when thresholds in vapour-pressure deficit (\<4\ kPa) and dead fuel moisture content (\<7\%) were exceeded. Predictions from the model showed a high degree of agreement with the raw fire severity maps. The proposed models have the potential to provide guidance on the likelihood of crown fire during fire events.

}, keywords = {Bushfire, extreme bushfires, fire behaviour., weather conditions}, issn = {508}, author = {Alex Filkov and Thomas Duff and Trent Penman} } @article {bnh-5424, title = {Determining Threshold Conditions for Extreme Fire Behaviour Annual Report 2017-2018}, number = {460}, year = {2019}, month = {03/2019}, institution = {Bushfire and Natural Hazards CRC}, address = {Melbourne}, abstract = {

Extreme fires cause disproportionate impacts on the environment and the community. There are significant incentives to being able to predict their occurrence and behaviour. Most existing fire behaviour models have been developed based on data and observations of fires that were small to moderate in size. Consequently, they are not able to emulate the dynamic bushfire behaviour that can occur under extreme conditions.

The main aim of this project is to investigate the conditions and processes under which bushfire behaviour undergoes major transitions, including fire convection and plume dynamics, evaluating the consequences of eruptive fire behaviour (spotting events, convection driven wind damage, rapid fire spread) and determining the combination of conditions for such behaviours to occur (e.g. unstable atmosphere, fuel properties and weather conditions). To do this the project was separated into two phases. The first phase of the project was focused on data collection about extreme fires, analysis the frequency of occurrence of extreme fire phenomena and determination the potential of including them in fire behaviour models.

}, keywords = {extreme fire behaviour, fire behavour, fire management}, author = {Alex Filkov and Thomas Duff and Trent Penman} } @article {bnh-6393, title = {Frequency of Dynamic Fire Behaviours in Australian Forest Environments}, journal = {Fire}, volume = {3}, year = {2019}, month = {12/2019}, abstract = {

Wildfires can result in significant social, environmental and economic losses. Fires in which dynamic fire behaviours (DFBs) occur contribute disproportionately to damage statistics. Little quantitative data on the frequency at which DFBs occur exists. To address this problem, we conducted a structured survey using staff from fire and land management agencies in Australia regarding their experiences with DFBs. Staff were asked which, if any, DFBs were observed within fires greater than 1000 ha from the period 2006{\textendash}2016 that they had experience with. They were also asked about the nature of evidence to support these observations. One hundred thirteen fires were identified. Eighty of them had between one and seven DFBs with 73\% (58 fires) having multiple types of DFBs. Most DFBs could commonly be identified through direct data, suggesting an empirical analysis of these phenomena should be possible. Spotting, crown fires and pyro-convective events were the most common DFBs (66\%); when combined with eruptive fires and conflagrations, these DFBs comprise 89\% of all cases with DFBs. Further research should be focused on these DFBs due to their high frequencies and the fact that quantitative data are likely to be available.

}, keywords = {anecdotal data, direct data, dynamic fire behaviours, indirect data, Wildfire}, doi = {https://doi.org/10.3390/fire3010001}, url = {https://www.mdpi.com/2571-6255/3/1/1}, author = {Alex Filkov and Thomas Duff and Trent Penman} } @conference {bnh-6549, title = {Quantifying dynamic fire behaviour phenomena using Unmanned Aerial Vehicle technology }, booktitle = {23rd International Congress on Modelling and Simulation}, year = {2019}, month = {12/2019}, address = {Canberra}, abstract = {

Catastrophic wildfires are often a result of dynamic fire behaviours. Although some of these behaviours have been described and investigated, others require further study. Fire coalescence and junction fires are particular cases of merging fire fronts and are common phenomena observed during bushfires. They are important as they can cause rapid escalation of fire behaviour and be dangerous for ground-based emergency personnel. There are a few studies devoted to investigation of merging fires in field conditions. There is a need for high temporal and spatial measurements of fire behaviour in field conditions in order to better understand this phenomenon and evaluate risks during bushfires and prescribed burning. The aim of this study was to test emerging technologies for better quantification of fire behaviour at field scales and evaluate their potential as an operational tool.

Several small and medium scale field experiments were conducted during April 2019 on farmland in Victoria, Australia. Harvested wheat fields were used as experimental plots, as they form relatively homogeneous fuel beds. Fuel height varied from 18 to 40 cm with fuel load and moisture content at 1.1 t/ha and 11.9 \% respectively. Wind speed varied in the range of 1.5-6.5 m/s. An Unmanned Aerial Vehicle (UAV) was used to capture high definition video imagery of fire propagation in synchronisation with sensor data from the on-board Global Positioning System (GPS) and Inertial Measurement Unit (IMU). These sensors enabled the platform/camera orientation and position in space to be aligned with the video footage of fire propagation and to be georeferenced in GIS software.

Twenty-one junction fires and five inward parallel fire fronts (parts of the fire lines approaching each other) were identified during the experiments. The rate of spread (ROS) of merging fire fronts was found to be at least two times higher than for the basic fire fronts (the rate of spread of a linear fire front in the same fuel bed in no-slope conditions) and for junction fires with acute angles (\< 14{\textdegree}) it increased 6 times and more. Inward parallel fire fronts spread much slower, varying between 0.05 and 0.25 m/s. Forty-six percent of junction fires had increase of the ROS at the final stage of the merging process in contrast to Thomas et al. (2017) and Viegas et al. (2012). Also, it was observed that the angle between two oblique fire fronts did not change significantly in time for the initial angles smaller than 34{\textdegree}. It can be assumed that the main fire front influences on the shape and ROS respectively of junction fires and laboratory experiments cannot fully replicate these conditions.

Although the initial experimental conditions were very different in relation to scale, fuel and wind conditions, similar ROS to that shown in numerical simulations by Thomas et al. (2017) were observed in our field experiments. Further investigation is required to explain the similarities as the relationship between fuel load, wind speed and scale is not known. The comparison of corrected values of dimensionless ROS for different angles between fire fronts with laboratory experiments of Viegas et al. (2012) showed reasonable quantitative agreement.

These experiments have shown that the method of using UAV{\textquoteright}s to capture georeferenced video footage can be used reliably to quantify fire behaviour phenomena for research, operation and management purposes.

Catastrophic wildfires are often a result of dynamic fire behaviours. Although some of these behaviours have been described and investigated, others require further study. Fire coalescence and junction fires are particular cases of merging fire fronts and are common phenomena observed during bushfires. They are important as they can cause rapid escalation of fire behaviour and be dangerous for ground-based emergency personnel. There are a few studies devoted to investigation of merging fires in field conditions. There is a need for high temporal and spatial measurements of fire behaviour in field conditions in order to better understand this phenomenon and evaluate risks during bushfires and prescribed burning. The aim of this study was to test emerging technologies for better quantification of fire behaviour at field scales and evaluate their potential as an operational tool.

Several small and medium scale field experiments were conducted during April 2019 on farmland in Victoria, Australia. Harvested wheat fields were used as experimental plots, as they form relatively homogeneous fuel beds. Fuel height varied from 18 to 40 cm with fuel load and moisture content at 1.1 t/ha and 11.9 \% respectively. Wind speed varied in the range of 1.5-6.5 m/s. An Unmanned Aerial Vehicle (UAV) was used to capture high definition video imagery of fire propagation in synchronisation with sensor data from the on-board Global Positioning System (GPS) and Inertial Measurement Unit (IMU). These sensors enabled the platform/camera orientation and position in space to be aligned with the video footage of fire propagation and to be georeferenced in GIS software.

Twenty-one junction fires and five inward parallel fire fronts (parts of the fire lines approaching each other) were identified during the experiments. The rate of spread (ROS) of merging fire fronts was found to be at least two times higher than for the basic fire fronts (the rate of spread of a linear fire front in the same fuel bed in no-slope conditions) and for junction fires with acute angles (\< 14{\textdegree}) it increased 6 times and more. Inward parallel fire fronts spread much slower, varying between 0.05 and 0.25 m/s. Forty-six percent of junction fires had increase of the ROS at the final stage of the merging process in contrast to Thomas et al. (2017) and Viegas et al. (2012). Also, it was observed that the angle between two oblique fire fronts did not change significantly in time for the initial angles smaller than 34{\textdegree}. It can be assumed that the main fire front influences on the shape and ROS respectively of junction fires and laboratory experiments cannot fully replicate these conditions.

Although the initial experimental conditions were very different in relation to scale, fuel and wind conditions, similar ROS to that shown in numerical simulations by Thomas et al. (2017) were observed in our field experiments. Further investigation is required to explain the similarities as the relationship between fuel load, wind speed and scale is not known. The comparison of corrected values of dimensionless ROS for different angles between fire fronts with laboratory experiments of Viegas et al. (2012) showed reasonable quantitative agreement.

These experiments have shown that the method of using UAV{\textquoteright}s to capture georeferenced video footage can be used reliably to quantify fire behaviour phenomena for research, operation and management purposes.

}, keywords = {fire front propagation, merging fire fronts, Remote measurements, UAS}, url = {https://www.researchgate.net/publication/338412609_Quantifying_dynamic_fire_behaviour_phenomena_using_Unmanned_Aerial_Vehicle_technology}, author = {Alex Filkov and Brett Cirulis and Trent Penman} } @article {bnh-4998, title = {Determining threshold conditions for extreme fire behaviour}, number = {417}, year = {2018}, month = {10/2018}, institution = {Bushfire and Natural Hazards CRC}, abstract = {

Flame spread is an important process in the propagation of bushfires. The likelihood of ignition and combustion rates of fuels are dependent on the type and nature of the heat flux. The majority of previous research has used static heat flux, whereby a consistent heating source is used to ignite samples in a laboratory setting. This is despite the highly dynamic heating regimes typically observed during structural and wildland fires.

}, keywords = {Fire, fire behaviour., fire modelling, fire severity, modelling}, author = {Alex Filkov and Thomas Duff and Trent Penman} } @conference {bnh-4743, title = {Extreme fire behaviours: Surveying fire management staff to determine behaviour frequencies and importance}, booktitle = {AFAC18}, year = {2018}, month = {09/2018}, publisher = {Bushfire and Natural Hazards CRC}, organization = {Bushfire and Natural Hazards CRC}, address = {Perth}, abstract = {

An understanding how bushfires cause damage is important if they are to be effectively managed. Extreme fire behaviours (EFBs) are phenomena that occur within intense fires that have been shown to contribute greatly to their to impacts. However, there exists little understanding regarding how often particular EFBs occur, how these contribute to fire behaviour and what importance should be allocated to each in the development of models for decision support. To address this problem, we surveyed fire fighters from fire and land management agencies in Australia regarding their experiences with EFBs. All fires greater than 1000 ha in the period 2006-2016 were considered in the survey. Representatives were asked which, if any, EFBs they had observed and whether there was any documentation to support these observations. We found that EFBs are common in large fires. In more than 60 \% of case studies, each bushfire had two and more EFBs simultaneously (or one after another). Our survey indicated that Spotting, Crown fires, Pyro-convective events, Eruptive fires and Conflagrations are the most commonly observed EFBs, and so should be a priority for research. The relative commonness of direct evidence available for EFBs is indicative that there should be the potential for further study of these phenomena.\ 

}, author = {Alex Filkov and Thomas Duff and Trent Penman} } @article {bnh-4458, title = {Improving Fire Behaviour Data Obtained from Wildfires}, journal = {Forests}, volume = {9}, year = {2018}, month = {02/2018}, abstract = {

Organisations that manage wildfires are expected to deliver scientifically defensible decisions. However, the limited availability of high quality data restricts the rate at which research can advance. The nature of wildfires contributes to this: they are infrequent, complex events, occur with limited notice and are of relatively short duration. Some information is typically collected during wildfires, however, it is often of limited quantity and may not be of an appropriate standard for research. Here we argue for a minimum standard of data collection from every wildfire event to enhance the advancement of fire behaviour research and make research findings more internationally relevant. First, we analyse the information routinely collected during fire events across Australia. Secondly, we review research methodologies that may be able to supplement existing data collection. Based on the results of these surveys, we develop a recommended list of variables for routine collection during wildfires. In a research field typified by scarce data, improved data collection standards and methodologies will enhance information quality and allow the advancement in the development of quality science.

}, keywords = {data collection and management, Fire behaviour, research utilization, standard.}, doi = {10.3390/f9020081}, url = {http://www.mdpi.com/1999-4907/9/2/81}, author = {Alex Filkov and Thomas Duff and Trent Penman} } @article {bnh-6037, title = {Particle tracking and detection software for firebrands characterization in wildland fires}, journal = {Fire Technology}, volume = {55}, year = {2018}, month = {12/2018}, pages = { 817-836}, abstract = {

Detection and analysis of the objects in a frame or a sequence of frames (video) can be used to solve a number of problems in various fields, including the field of fire behaviour and risk. A quantitative understanding of the short distance spotting dynamics, namely the firebrand density distribution within a distance from the fire front and how distinct fires coalesce in a highly turbulent environment, is still lacking. To address this, a custom software was developed in order to detect the location and the number of flying firebrands in a thermal image then determine the temperature and sizes of each firebrand. The software consists of two modules, the detector and the tracker. The detector determines the location of the firebrands in the frame, and the tracker compares the firebrand in different frames and determines the identification number of each firebrand. Comparison of the calculated results with the data obtained by the independent experts and experimental data showed that the maximum relative error does not exceed 12\% for the low and medium number of firebrands in the frame (less than 30) and software agrees well with experimental observations for firebrands \> 20 {\texttimes} 10-5\ m. It was found that fireline intensity below 12,590\ kW\ m-1\ does not change significantly 2D firebrand flux for firebrands bigger than 20 {\texttimes} 10-5\ m, while occasional crowning can increase the firebrand flux in several times. The developed software allowed us to analyse the thermograms obtained during the field experiments and to measure the velocities, sizes and temperatures of the firebrands. It will help to better understand of how the firebrands can ignite the surrounding fuel beds and could be an important tool in investigating fire propagation in communities.

}, keywords = {Firebrand detection, Firebrand tracking, Firebrands, Structural, Wildland}, doi = {https://doi.org/10.1007/s10694-018-0805-0}, url = {https://link.springer.com/article/10.1007/s10694-018-0805-0}, author = {Alex Filkov and Sergey Prohanov} } @article {bnh-4819, title = {Simulation of fuel bed ignition by wildland firebrands}, journal = {International Journal of Wildland Fire}, volume = {27}, year = {2018}, month = {07/2018}, abstract = {

A 3-D mathematical model of fuel bed (FB) ignition initiated by glowing firebrands originating during wildland fires is proposed. In order to test and verify the model, a series of experiments was conducted to determine the FB ignition time by a single pine bark and twig firebrand (Pinus sylvestris). Irrespective of the pine bark sample sizes and experimental conditions, the ignition of the FB was not observed. Conversely, pine twigs, under certain parameters, ignited the FB in the range of densities (60{\textendash}105 kg m-3) and with the airflow velocity of >=2 m s-1. The results of the mathematical modelling have shown that a single pine bark firebrand <=5 cm long with a temperature of T <= 1073 K does not ignite in the flaming mode the FB, and only the thermal energy of larger particles is sufficient for flaming ignition of the adjacent layers of the FB. The analysis of the results has shown that the firebrand length is a major factor in the initiation of ignition. Comparison of the calculated and observed FB ignition times by a single firebrand have shown that our modelling accords well with the experimental results.

}, keywords = {critical conditions, experiment, ignition, modelling, spotting.}, url = {https://www.publish.csiro.au/WF/WF17083}, author = {O. V. Matvienko and D. P. Kasymov and Alex Filkov and O. I. Daneyko and D. A. Gorbatov} } @article {bnh-5141, title = {Determination of smoldering time and thermal characteristics of firebrands under laboratory conditions}, journal = {Fire Safety Journal}, volume = {91}, year = {2017}, month = {07/2017}, pages = {791-799}, chapter = {791}, abstract = {

The laboratory experiment was conducted to simulate the transfer of smouldering particles produced in forest wildfires by a heated gas flow. The pine bark pieces with the linear dimensions\ L=(15; 20; 30) mm and a thickness of\ h=(4-5)mm were selected as model particles. The rate and temperature of the incident flow varied in the range of 1{\textendash}3m/s and 80{\textendash}85{\textdegree}C, respectively. The temperature of the samples was recorded using a thermal imager. To determine the minimum smouldering temperature of pine bark, the thermal analysis was conducted. The minimum smouldering temperature of pine bark was found to be 190{\textdegree}C. This temperature will cause thermal decomposition of bark only at the first stage (oxidation of resinous components). In the study the smouldering time, the temperature and the weight of samples were obtained and analyzed under various experimental conditions. The data analysis shows that the increase in the particle size leads to the decrease in their mass loss, and the rate change of the incident flow does not practically influence the mass change. For particles with the linear dimensions of 10mm and 20mm, the mass varies from 6\% to 25\%. The maximum mass loss is observed for the flows with a rate of 1 and 2m/s. The results have shown that the increase in the particle size leads to the increase in the smouldering time. The position of the particle plays an important role, the effect of which increases with increasing the particle size. The calculations showed that the smouldering time of bark samples is long enough for the particles to serve as new sources of spot fires. The particles were found to be transported to a distance of 218m from the fire line which can certainly influence the propagation of the fire front.

}, doi = {https://doi.org/10.1016/j.firesaf.2017.03.080}, url = {https://www.sciencedirect.com/science/article/pii/S037971121730125X}, author = {Vladimir Fateev and Mikhail Agafontsev and Sergey Volkov and Alex Filkov} } @article {bnh-4206, title = {Determining threshold conditions for extreme fire behaviour: annual project report 2016-17}, number = {319}, year = {2017}, month = {09/2017}, institution = {Bushfire and Natural Hazards CRC}, address = {Melbourne}, abstract = {

Organisations that manage bushfires are expected to deliver scientifically defensible decisions. However, the limited availability of high quality data restricts the rate at which research can advance. The nature of bushfires contributes to this; they are infrequent, complex events, occur with limited notice and are of relatively short duration. Some information is typically collected during bushfires however it may not be of an appropriate standard for research. In the past year we have focused on the information that is typically collected during fires. First we reviewed the information routinely collected during fire events across Australia. Secondly, we reviewed research methodologies that may be able to supplement existing data collection. Based on the results of these surveys, we developed a recommended list of attributes for routine collection during bushfires. We also suggest standards of data collection from bushfire events to enhance the advancement of fire behaviour research and make research findings more internationally relevant. In a research field typified by scarce data, improved data collection standards and methodologies will enhance information quality and allow the advancement in the development of quality science (1). In addition to the fire data review, we investigated embers, including their production and how they burn (2,3).

}, issn = {319}, author = {Alex Filkov and Thomas Duff and Trent Penman} } @article {bnh-5183, title = {Investigation of firebrand generation from an experimental fire: development of a reliable data collection methodology}, journal = {Fire Safety Journal}, volume = {91}, year = {2017}, month = {07/2017}, pages = {864-871}, chapter = {864}, abstract = {

An experimental approach has been developed to quantify the characteristics and flux of firebrands during a management-scale wildfire in a pine-dominated\ ecosystem. By characterizing the local fire behavior and measuring the temporal and\ spatial variation\ in firebrand collection, the flux of firebrands has been related to the fire behavior for the first time. This linkage is seen as the first step in risk mitigation at the wildland urban interface (WUI). Data analyses allowed the evaluation of firebrand flux with respect to observed fire intensities for this ecosystem. Typical firebrand fluxes of 0.82{\textendash}1.36pcsm-2s-1\ were observed for fire intensities ranging between 7.35{\textpm}3.48MWm-1\ to 12.59{\textpm}5.87MWm-1. The experimental approach is shown to provide consistent experimental data, with small variations within the firebrand collection area. Particle size distributions show that\ small particles\ of area 0.75{\textendash}5{\texttimes}10-5m2\ are the most abundant (0.6{\textendash}1pcsm-2s-1), with the total flux of particles \>5{\texttimes}10-5m2\ equal to 0.2{\textendash}0.3 pcsm-2s-1. The experimental method and the data gathered show substantial promise for future investigation and\ quantification\ of firebrand generation and consequently a better description of the firebrand risk at the WUI.

}, doi = {https://doi.org/10.1016/j.firesaf.2017.04.002}, url = {https://www.sciencedirect.com/science/article/pii/S0379711217301819?via\%3Dihub}, author = {Jan Thomas and Eric Mueller and Simon Santamaria and Michael Gallagher and Mohamad El Houssami and Alex Filkov and Kenneth Clark and Nicholas Skowronski and Rory M Hadden and William Mell and Albert Simeoni} } @article {bnh-5140, title = {Investigation of firebrand production during prescribed fires conducted in a pine forest}, journal = {Proceedings of the Combustion Institute}, volume = {36}, year = {2017}, month = {11/2016}, pages = {3270}, chapter = {3263}, abstract = {

This paper represents a study on the characterization of firebrand production which was carried out, using experimental fires conducted as prescribed fires in the New Jersey Pine Barrens, USA in March of 2013{\textendash}2015. Several preliminary techniques were tested to characterize the firebrand production. Firebrands were collected from three plots for each year and analyzed for mass and size distribution. Thermal imagery was used to measure the velocity, size and number of firebrands in 2014 and 2015. The distribution of firebrands was evaluated in a monitored volume during the experiment. It was found that not less than 70\% of collected particles were bark fragments and the rest were pine and shrub branches. The number of firebrands decreases with increasing the cross section area of firebrands. The mass of the particles varied from 5 to 50mg, and the maximum number of the particles was observed for the mass range of 10{\textendash}20mg. About 80\% of firebrands were particles with the cross section area of (5{\textendash}20) {\texttimes} 10-5\ m2. These results are consistent with the available observations of real fires\ [1],\ [2]. Processing of infrared video showed that starting from a distance of 13m from fire front, an increasing number of firebrands were observed in a controlled volume, increasing in number up to 180 per second. Relationships describing the time-variation of the number of particles that dropped on a 1.4m2\ surface and the number of particles that flew through a 1m3\ volume were obtained. Comparing the experimental and calculated data, we can conclude that these relationships allow us to describe the two numbers with an acceptable accuracy (adj. R2\ 0.74 and 0.86, respectively). In addition, the velocity of the particles, which depended on the wind velocity, was in the 0.1{\textendash}10.5m/s range, with an average value of 2.5m/s.

}, doi = {https://doi.org/10.1016/j.proci.2016.06.125}, url = {https://www.sciencedirect.com/science/article/pii/S1540748916301833$\#$!}, author = {Alex Filkov and Sergey Prohanov and Eric Mueller and D. P. Kasymov and Pavel Martynov and Mohamad El Houssami and Jan Thomas and Nicholas Skowronski and Bret Butler and Michael Gallagher and Kenneth Clark and William Mell and Robert Kremens and Rory M. Madden and Albert Simeoni} } @article {bnh-5182, title = {Utilization of remote sensing techniques for the quantification of fire behavior in two pine stands}, journal = {Fire Safety Journal}, volume = {91}, year = {2017}, month = {07/2017}, pages = {845-854}, chapter = {845}, abstract = {

Quantification\ of field-scale fire behavior is necessary to improve the current scientific understanding of wildland fires and to develop and test relevant, physics-based models. In particular, detailed descriptions of individual fires are required, for which the available literature is limited. In this work, two such field-scale experiments, carried out in pine stands under\ mild conditions, are presented. A particular focus was placed on non-intrusive\ measurement, as the capabilities of advanced remote sensing techniques, along with more traditional approaches, are explored. A description of the fires is presented, with spread occurring predominantly in the surface fuels with intensities in the range of 200{\textendash}4400kWm-1, and punctuated by isolated regions of crown fire. The occurrence of crown fire is investigated and linked to regions of greater canopy density, and it is found that the total fire intensity may increase locally to as much as 21,000kWm-1. The light winds do not appear to play a\ direct role\ in the changes in fire behavior, while fuel structure may be important. The measurements described herein provided a reasonable overall description of the fires, however, the current resolution (both spatial and temporal) falls short of definitively explaining some transitional aspects of the fire behavior, and future improvements are suggested.

}, doi = {https://doi.org/10.1016/j.firesaf.2017.03.076}, url = {https://www.sciencedirect.com/science/article/pii/S0379711217301728}, author = {Eric Mueller and Nicholas Skowronski and Kenneth Clark and Michael Gallagher and Robert Kremens and Jan Thomas and Mohamad El Houssami and Alex Filkov and Rory M Hadden and William Mell and Albert Simeoni} } @article {bnh-2922, title = {Determining threshold conditions for extreme fire behaviour: Annual project report 2015-2016}, number = {175}, year = {2016}, month = {08/2016}, institution = {Bushfire and Natural Hazards CRC}, address = {Melbourne}, abstract = {

As extreme fires cause a disproportionate amount of impact to the environment and the community, there are significant incentives to being able to predict their occurrence and behaviour. Most existing fire behaviour models have been developed based on data and observations of fires that were small to moderate in size. Consequently, they are not able to emulate the dynamic bushfire behaviour that can occur under extreme conditions.

Indeed, current operational fire spread models assume that fires will burn at an approximately constant (quasi-steady) rate of spread under a specific set of environmental conditions (e.g. VESTA, McArthur Mk5, CSIRO models). While a number of advances have been made in understanding bushfire development under extreme conditions, these have not been quantified in a manner that is suitable for inclusion in a fire behaviour modelling framework.

The main aims of this project are to investigate the conditions and processes under which bushfire behaviour undergoes major transitions, including fire convection and plume dynamics, evaluating the consequences of eruptive fire behaviour (spotting events, convection driven wind damage, rapid fire spread) and determining the combination of conditions for such behaviours to occur (e.g. unstable atmosphere, fuel properties and weather conditions). To do this the collation and analysis of existing data on extreme fire behaviour will be done.

}, issn = {175}, author = {Thomas Duff and Trent Penman and Alex Filkov} }