@article {bnh-8329, title = {Analysis and characterisation of bushfire-meets-prescribed burn events from the 2019-20 fire season - Black Summer final report}, number = {683}, year = {2022}, month = {03/2022}, institution = {Bushfire and Natural Hazards CRC}, address = {Melbourne}, abstract = {

The objective of this project was stated in the Research Services Agreement as: {\textquotedblleft}to develop a novel dataset that will capture information about individual bushfire-meets-prescribed burn events. The initial focus will be on those interactions that occurred during the 2019/20 fire season.{\textquotedblright} In other words, the project was to design a database that will allow evaluation of prescribed burns from planning stages to ultimate outcomes, and start using the data for some cases. In this report, we begin by outlining this dataset and its sources of information, though we have not populated it. Instead, we list potential evaluations that could be done with and conduct two evaluations with components of the data.

The core of the proposed fire-meets-fire dataset is matched reporting from the Burn Plan (before) and Burn Report (on completion), especially area, fuel, moisture and weather variables. Some of this is not routinely reported in the current Elements System (for example 21\% of burns had no actual area burnt recorded and most burns were missing fuel information). The dataset should also ingest information from fire severity mapping (which is now routine) and smoke impact. If the burn meets a bushfire a new range of information is available and should be ingested, including the severity of the bushfire within the burn. The advantage that the burn gave to firefighters is hard to gauge simply from fire severity, so additional information is needed, most importantly from firefighter interviews, but also by more detailed GIS examination of bushfire behavior.

There are many evaluations that could be done with this dataset, from simple metrics such as percent of planned area actually burnt, to refinement of weather prescriptions for burns to whole-of-program evaluations applied to all burns such as the severity analysis presented here.

Sections 3 and 4 are examples of whole of program evaluations. Section 4 is an analysis of severity reduction in the 2019/20 bushfires relating the occurrence of high severity fire in ~100,000 points to the fire history at those points, and controlling for vegetation, weather and topography. This found that in dry sclerophyll, recent burning (up to ~five years) reduced the probability of high severity fire and even more so if that previous burn was at low severity.

Section 4 uses visual interpretation of the 2019/20 bushfire severity and progression mapping to attribute each previous prescribed burn with its effect on the bushfire. This ranged from stopping the bushfire altogether (having a common boundary) to simple severity reduction (was the bushfire severity reduced in the burn?). We found that 30\% of burns from 2014 were encountered by the bushfires. Of these 509 burns, 13\% of them were aligned with the final fire boundary, 42\% of recent burns (one or two years old) caused some unburnt patches within the burn, and 68\% caused a severity reduction. Burns older than this had much less effect, and we found two cases where a burn left an unburnt shadow behind it (meaning shadows are very rare events). We were able to cross-reference our interpretation for 14 burns to interviews from another pilot project. This revealed broad agreement, but also highlighted several cases where a burn gave firefighters an advantage that could not be found in the GIS. Three of these were cases where the bushfire slowed down (sometimes for several days), allowing firefighters time to prepare. There were two cases where burns outside of the burn perimeter effectively reduced spotting activity.

The project demonstrates what can be done to evaluate prescribed burning programs and that a wide range of data is required to do this thoroughly. The 2019/20 bushfire season was extraordinary in many ways. Our analysis suggests that one of these ways was that prescribed burns only reduced fire behavior if they were one or two years old. Analyses of previous seasons generally find a longer lasting effect. Even so, there were many instances where prescribed burns helped firefighters, including in ways that are not obvious in GIS analyses.

}, keywords = {2019-20, analysis, black summer, Bushfire, characterisation, prescribed burn}, issn = {683}, author = {Owen Price and James Barker and Simin Rahmani and Wilkinson, Carrie and Donald MacDonald} } @article {bnh-8253, title = {Coupled fire-atmosphere simulations of five Black Summer fires using the ACCESS-Fire model - Black Summer final report}, number = {705}, year = {2021}, month = {05/2021}, institution = {Bushfire and Natural Hazards CRC}, address = {Melbourne}, abstract = {

Context

This research builds on previous work completed during the Coupled fire-atmosphere modelling ACCESS-Fire project, by conducting case studies of five major bushfires that occurred across Australia during the 2019-20 summer. The previous work provided valuable insights into the drivers of periods of extreme fire behaviour associated with the Waroona fire in WA, and the Sir Ivan fire in NSW.

The main objectives of this project are: to investigate the meteorological drivers of extreme fire behaviour at five further fire events; to further test the reliability and stability of the model in different environments across Australia; and to support and share learnings from the events of the 2019-20 summer with partner agencies.

The fire events nominated by state jurisdictions for investigation were: Badja Forest (New South Wales), Stanthorpe (Queensland), Green Valley Talmalmo/Corryong\ (NSW/Victoria), Kangaroo Island (South Australia); and Yanchep (Western Australia).

The case studies show that the local context for each fire is important. Each of the fires posed significant challenges in different ways. In the heavily forested areas of NSW and Victoria, the sheer size, intensity, and duration of the fires were distinctive. At other fires, the proximity of local communities and infrastructure posed serious challenges. All fires were active in the overnight period when conventional fire danger indices typically suggest a decrease in fire activity.

The marine boundary layer, local coastal effects and topography combined to generate complex wind flows that influenced the progression of the Kangaroo Island fire. We also studied the way in which the sea breeze circulation interacted with the Yanchep fire, and examined the impact of a prescribed burn on the rate and direction of spread of the Stanthorpe fire under extreme fire weather conditions.

This project has explored gaps in knowledge and understanding of the processes at play during these unusual events by using the Bureau{\textquoteright}s ACCESS-Fire model to examine the local three-dimensional interactions between the fires and the atmosphere. The learnings from this project may be applied to shape future fire weather products and services.

Method

Based on discussions with our partners in fire agencies, together with documents (including photographs and video) and information on fire spread, fuel types and fuel moisture and atypical fire behaviour, we have run a series of simulations and prepared case study chapters for each of the five fires.

The ACCESS-Fire model was initialised using information provided by fire agencies on ignition location or fire line perimeter and fuel type and availability. Several simulations were conducted for each of the fires, with a focus on different time periods of interest and using updated fire polygon boundaries based on available line scan imagery.

The model configuration does not permit the simulations to account for suppression activities by fire agencies, changes in fuel types on the urban interface, or the impact of roads or other fire breaks in reducing the rate of spread of the fire. Another limitation is that the simulations are a single realisation, when in reality, consideration of forecast uncertainty (for example through running an ensemble scheme) would capture a range of potential outcomes.\ 

Learnings from the case studies reinforce and refine some previous learnings from historical fire events and uncover some new insights into the processes driving the periods of unusual fire behaviour that were observed during the 2019/20 season.

Key findings

The case study analyses have provided valuable insights into meteorological aspects of observed extreme fire behaviour during the 2019/20 summer. Key findings for each of the five case studies are included in the individual chapters for each fire and a synthesis is provided here.\ 

The ACCESS-Fire simulations run at 300 m spatial resolution show that some of the most dangerous effects of the fires, in particular damaging and destructive winds, are fire driven and therefore very localised at a much finer scale than current fire weather products.

The depth, elevation and structure of low-level jets over topography was a critical driver of overnight fire activity.\  Given that these jets are driven by larger scale processes (typically synoptic scale), there is an opportunity to develop new tools based on numerical weather prediction output that highlight the location and intensity of these features. Such tools would provide additional information for meteorologists and FBANs on the strength and height of representative winds for input to two-dimensional fire spread models and could be used to alert fire managers to the risk of atypical fire spread in the overnight period.

A key theme that emerged from the case studies and discussions with stakeholders was the consistent occurrence of heatwaves and their influence on boundary layer structure overnight and on inhibiting fuel moisture recovery during the overnight period. Further research quantifying the effects of overnight heatwaves is required to appropriately plan for the increased risk to communities and fire crews in a changing climate, as the frequency of elevated overnight temperatures has increased over the last few decades and is projected to increase further (along with other factors influencing fire activity).\ \ 

Deep moist pyroconvection producing pyrocumulus (pyroCu) or pyrocumulonimbus (pyroCb) clouds was a feature of the 2019-20 fire season and a record number of sustained outbreaks of pyroCbs occurred.\  However, the five fires examined here were not all associated with pyroCb, highlighting that it is not the sole weather phenomenon associated with extreme fire behaviour. In particular, no lightning was detected within the Green Valley Talmalmo fire (that subsequently became the Corryong fire when it burned into Victoria) as it burned through Green Valley, which shows that dangerous tornado-strength fire-generated winds can occur without pyroCb.

The simulations produced fire-generated extreme winds associated with both rotation and straight-line flow, which present a serious hazard. ACCESS-Fire simulated rotating winds in the updraft of the Green Valley Talmalmo/Corryong fire. More work is required to understand the mechanisms for these, they are likely related to the high intensity of the fire, coupled with topographic influences.

Spot fires were an important component in the observed rate of spread, particularly in the forest fires overnight. The extremely dry, drought-affected fuel beds meant that the ignition efficiency of spot fires was enhanced compared to an average season. Inclusion of a spotting parameterisation in ACCESS-Fire would accelerate the forwards fire spread and improve validation of the simulated fire perimeters.\ 

Coastal processes were evident in the simulations of the Kangaroo Island and Yanchep fires. Localised wind effects in the simulations showed interactions between the fire and maritime airmass including sea breeze circulations can modify the updrafts associated with the fire as well as produce rapid transitions in fire intensity around a fire perimeter. Cooler moister air associated with a maritime airmass may not necessarily reduce fire intensity, depending on its depth and penetration inland.

Utilisation - where to from here?

The high level of engagement in this work from a range of stakeholders has demonstrated the value of this research and the appetite for operational application.\ 

The learnings from this work should be incorporated into training packages tailored for fire meteorologists and FBANs that describe characteristics of the local meteorological environment favourable for extreme fire behaviour. Such training will complement other current research and training on fire behaviour aspects such as spotting and potential for pyroCb.

This work, which has been conducted in close collaboration with partners in fire agencies, has demonstrated that a comprehensive understanding of the mechanisms driving fire behaviour requires a multidisciplinary approach. Similarly, the successful application of fire behaviour and meteorology knowledge in operations requires locally connected specialised expertise, combined with tailored modelling tools to inform objective, evidence-based decisions.

The insights gathered from these five case studies have further demonstrated the value of this high resolution coupled modelling approach. In order to progress ACCESS-Fire to an effective operational tool, more robust testing of the model is required, in addition to the more subjective assessments that have been made through the case study work. This would include technical testing, additional sensitivity testing and routine verification.

This project has demonstrated that the Bureau{\textquoteright}s technology and simulation capability, scientific expertise and established relationships with fire agencies can meet the Australian community{\textquoteright}s need to understand the drivers of fire behaviour during the 2019-20 fire season. In doing so, we have further developed and validated our modelling systems and made progress towards their future operational use.

}, keywords = {ACCESS-Fire, black summer, coupled, fire-atmosphere, simulations}, issn = {705}, author = {Mika Peace and Barry Hanstrum and Jesse Greenslade and Dragana Zovko-Rajak and Abhik Santra and Jeffrey Kepert and Paul Fox-Hughes and Harvey Ye and Tasfia Shermin and Jeffrey Jones} } @article {bnh-8189, title = {Established and emerging uses of predictive services in Victoria}, number = {697}, year = {2021}, month = {08/2021}, institution = {Bushfire and Natural Hazards CRC}, address = {MELBOURNE}, abstract = {

The recent 2019-20 Black Summer bushfire season brought both sector and public attention to the important role that predictive services can play in mitigating and preventing the loss of life and assets from bushfires.

This research study focused on two key questions:

  1. What are the key features of effective relationships between Fire Behaviour Analysts (FBANs) and their users within emergency management?
  2. How might the predictive services role and predictive services outputs be developed in the future?

We explored these questions by conducting twenty-five (25) semi-structured interviews with key practitioners who either perform the FBAN role or use predictive services in Victoria.

Our findings are categorised into 7 topics:

1. Interviewee background: The interviewees included people who represent the following operational roles: FBAN, State Regional Commander, State Agency Commander, Level 3 Incident Controller, Level 3 Public Information Officer, Level 3 Planning Officer, Level 3 Operations Officer, and Level 3 Situation Officer.

2. FBAN outputs: We collected data from FBANs and other operations staff who occupy roles which interact with and/or use the outputs produced by FBANs from within the broad emergency and incident control arrangements provided for within the Australasian Inter-service Incident Management System.

We found that the FBAN advice and products are used to:

Most interviewees agreed that the design and framing of outputs should be standardised for public dissemination, however, there was less consensus that such standardisation is required for operational purposes.

3. Trust in FBAN outputs: We found that in general:

Trust is an important factor in the high-pressure contexts of incident and land management, including both interpersonal trust and trust in particular tools and systems. We found that trust seems to depend, in part, upon users{\textquoteright} perceptions of a given FBAN{\textquoteright}s skills, level of experience, and knowledge of the area or context in which they are offering predictive intelligence. For FBANs, both having fireground experience and {\textquotedblleft}local knowledge{\textquotedblright} and being able to convince users that one has fireground experience and {\textquotedblleft}local knowledge{\textquotedblright} seem to be important factors in eliciting the trust of some users.

4. Timeliness of FBAN outputs: We explored whether FBANs produced advice and outputs in a timely manner. We found that:

For example, a {\textquotedblleft}quick and dirty{\textquotedblright} map of potential fire spread was seen to be acceptable during first attack. However, the pressure related to timeliness decreases during an extended attack and is substantially decreased during pre-event planning and planned burning, or in any instance where there is potentially more time for FBANs to converse with end-users, collect and validate intelligence and tailor the outputs to the end-users{\textquoteright} needs.

5. Benefits of releasing FBAN outputs publicly: We explored whether participants felt predictive outputs produced by FBANs (e.g., fire spread predictions) should be released to the community (i.e., affected communities and the general public) to facilitate their decision-making and planning during periods of significantly elevated fire danger (e.g., days of {\textquotedblleft}Extreme{\textquotedblright} fire danger rating). We found that:

Participants noted that there is a moral imperative to release information to assist members of the public in their decision-making in relation to fire hazards. Further, there was a sense amongst many participants that, by releasing FBAN products publicly, emergency management organisations could support trust-building between agencies and communities and better demonstrate their transparency and accountability when working with the community to plan for and respond to bushfires.

6. Risks of releasing FBAN products publicly: We explored with the participants whether they felt that it was a risk to release FBAN outputs to the community to facilitate their decision-making and planning on days of significantly elevated fire danger. In general, participants reported that there were low levels of risk associated with releasing FBAN outputs to the community to facilitate community decision-making and planning.

We found that, where there was unease amongst participants in relation to releasing FBAN outputs publicly, it was because of:

7. The future of the FBAN role: We explored whether participants felt that the FBAN role will continue to be important within the broad emergency and incident control arrangements. We found that:

With this in mind, it is important to understand that the development of predictive services must ensure that it is further integrated into emergency management arrangements outside the State Control Centre. Specifically, viewed in relation to other project findings, it is clear that for such development and integration to be effective, FBANs will be required to spend more time interacting with users. Such interactions may sometimes occur outside fire seasons, though it is also apparent that they also need to occur throughout the fire season, on firegrounds and in Incident Management Centres and Regional Control Centres, in order to grow FBANs{\textquoteright} skillsets, maintain trust with users, educate users about their outputs and adapt those outputs to user needs. Various users had suggestions about how predictive services might better serve their needs, the vast majority of which related to the refinement of output types and modes of presentation to incidents and situations as they emerge.

Following this feedback also means exploring the different ways that FBAN skillsets and competencies can be used to assist key decision-makers such as Incident Controllers and community information and warning teams which continue to be so important in terms of planning and responding to bushfires. These skillsets and competencies - at both state and regional levels - also have relevant application to conduct of planned burning, and both users and FBANs suggest that more use can be made of FBAN skillsets and competencies to assist the states land and fire management agencies in achieving fuel management goals.

Based on these findings, we make 4 recommendations, detailed as follows:

Recommendation 1: that emergency management agencies explore which FBAN outputs could be released to the community to support their planning and decision-making during bushfire season.

Recommendation 2: that emergency management agencies explore how FBANs and predictive service outputs can be utilised to better support other relevant functions such as the conduct of planned burning and public information.

Recommendation 3: that emergency management agencies explore the ongoing training and development needs of FBANs.

Recommendation 4: that emergency management agencies work with FBANs to develop continuous learning processes which can be used to improve predictive services after bushfire and planned burning seasons.

In terms of utilisation, our recommendations will require an implementation strategy which needs to be mindful of the requirements to continue to plan for and respond to ongoing incidents that require predictive services. Accordingly, we propose a staged approach to utilisation that is channelled through the Bushfire and Natural Hazards CRC Black Summer research group.

Finally, we have confidence that these findings and recommendations are relevant to many other jurisdictions in Australia, including Western Australia, Tasmania, South Australia, Australian Capital Territory, Queensland, and New South Wales, given their similarity in bushfire hazards, incident management systems, and the role and scope of predictive services.

}, keywords = {analysts, black summer, FBANs, Fire behaviour, predictive, services, Victoria}, issn = {697}, author = {Chloe Begg and Graham Dwyer and Timothy Neale and Ian Pollock} } @article {bnh-8000, title = {Growing the seeds: recovery, strength and capability in Gippsland communities}, year = {2021}, month = {04/2021}, institution = {Victoria University}, address = {Melbourne}, abstract = {

{\textquoteleft}Adversity is a cloak that shrouds great gifts. It is up to us to cast away the cloak and reveal all that lies within. This is the journey.{\textquoteright} {\textemdash} Milena Cifali, Mallacoota Time: The Lost Summer 2020

The 2019{\textendash}20 East Gippsland fires occurred during the most severe fire season ever recorded on the east coast of Australia. They burned from November 2019 to February 2020, damaging over half of the East Gippsland Shire, an area of over 1.16 million hectares. Over 400 dwellings and businesses were lost and four people lost their lives. Recovery had just begun when the COVID-19 pandemic hit. In the same way that the Black Saturday Bushfires have fundamentally changed how bushfires are seen, these events have changed how recovery will be thought about. Writing this report has been a confronting and humbling experience.

In initial conversations, it became clear that the community members who participated wanted a different conversation to the one they had been having. They were seeking to be heard and understood {\textendash} not as victims of the bushfires, but as people who needed support because of the bushfires. To accommodate this, the research has been shaped around the conversation they wanted to have, which is focused on community strengths and capabilities.

This study was undertaken when COVID-19 restrictions were in place, extending for two weeks after Melbourne{\textquoteright}s lockdown ended. As a result, this report represents a snapshot of the recovery process at that time, and contains material that may distress individuals who have been affected the bushfires and the COVID-19 pandemic.

This report does not aim to represent all community issues or speak for the whole community, but rather to identify overarching themes around capabilities raised by those who wished to participate in the study. Participants have spoken about their experiences; those observed in their home communities and other communities they are working with. We also acknowledge that since the end of Melbourne{\textquoteright}s lockdown and the easing of COVID-19-related restrictions, circumstances may have changed, affecting communities{\textquoteright} contexts; and government and non-government agencies may be acting on issues contained in this report.

The purpose of this report

The purpose of this report is to provide a starting point for assessing and understanding community capability practically, and to provide an indicative status of these in East Gippsland and Wellington Shires following the bushfires. It uses a systemic assessment of social, economic and risk contexts to examine community strengths and capabilities, and identify potential future pathways.

The first section of this report has a specific focus on the capabilities involved in community recovery and how they have been experienced by diverse groups within the East Gippsland and Wellington community. This is viewed through a strengths-focused lens. It also provides an initial assessment of the status of the capabilities identified, and the challenges, needs and opportunities that have arisen as part of the recovery experience.

The second section provides a broader picture of the comparative strengths, capabilities and needs identified in an online survey of those impacted by the bushfires in New South Wales and Gippsland through established community panels. The results show which aspects are shared more broadly, those partitioned by direct and indirect experience, and those specific to the East Gippsland community.

The third section provides an economic assessment of two local government areas {\textendash} East Gippsland and Wellington Shires {\textendash} to provide a high-level assessment of the economic influences and impacts on the intersection of the COVID-19 pandemic and bushfire recovery.

}, keywords = {black summer, Capability, communities, gippsland, recovery, strength}, isbn = {978-1-86272-829-5}, author = {Celeste Young and Roger Jones and Craig Cormick} } @article {bnh-8129, title = {Kangaroo Island Black Summer fire reconstruction}, number = {685}, year = {2021}, month = {07/2021}, institution = {Bushfire and Natural Hazards CRC}, address = {Melbourne}, abstract = {

In the 2019-20 summer, wildfire affected an area of around 200,000 hectares on Kangaroo Island, South Australia, in what has become known as the Black Summer, with significant ongoing social, economic and environmental impacts.

The Advanced Himawari Imager (AHI) onboard the geostationary satellite Himawari-8 provides infrared imagery at 2km spatial resolution at nadir in 10- minute intervals. This allows wildfires to be detected and monitored in quasi-real time using the Biogeographical Region and Individual Geostationary HHMMSS Threshold (BRIGHT) algorithm (Engel, Jones and Reinke, 2020), developed in partnership between the Royal Melbourne Institute of Technology (RMIT) and the Bushfire and Natural Hazard CRC. This report outlines the methods used to verify hotspots detected by the BRIGHT algorithm and reconstruct the Black Summer fires using spatio-temporal clustering.

}, keywords = {black summer, Fire, fire impacts, kangaroo island, reconstructions, remote sensing, Satellite}, issn = {685}, author = {Simon Ramsey and Karin Reinke and Nur Trihantoro and Simon Jones and Chermelle Engel} } @article {bnh-8192, title = {Risk mitigation from prescribed burning in Kangaroo Island and Mount Lofty Ranges - Black Summer final report}, number = {690}, year = {2021}, month = {08/2021}, institution = {Bushfire and Natural Hazards CRC}, address = {MELBOURNE}, abstract = {

According to the Independent Review into South Australia{\textquoteright}s 2019-20 Bushfire Season, conditions were the worst on record with fires resulting in the loss of three human lives, 196 homes, 660 vehicles, 68,000 livestock, $200m of agricultural production. Around 280,000 ha were burnt by the fires, including total or partial burning of several National Parks.

The Bushfire and Natural Hazards CRC commissioned this project as part of a larger set of Black Summer fires research projects aimed at understanding the record-breaking fire season. This project focuses on answering questions about the effectiveness of prescribed burning, also known as hazard reduction burning, in mitigating risk in two areas affected by fires during the season: The Mount Lofty Ranges east of Adelaide, and Kangaroo Island.

The key questions were:

  1. How does risk respond to treatment in Kangaroo Island, an area with little formal quantification of prescribed burning benefits and costs?
  2. What was the risk in the leadup to the 2019-20 fire season in the Mt Lofty Ranges, and how will risk change in the next five years as a result of the implied fuel reduction from the fires, as well as alternative prescribed burning strategies?

These questions were answered using a well developed methodology combining large scale fire behaviour simulations and Bayesian risk quantification. Similar analyses have been carried out for a range of case study landscapes in southern Australia as part of the Hectares to tailor-made solutions CRC project, with results available online via the end-user tool the Prescribed Burning Atlas, and also the NSW Bushfire Risk Management Research Hub{\textquoteright}s projects for the NSW Bushfire Inquiry.

We found a clear relationship between the rate of prescribed burning and area subsequently burnt by wildfire in the Kangaroo Island case study. This translated into reductions in loss of life and property as well. Risk mitigation was more sensitive to edge treatment than landscape treatment, although both reduced risk. Conversely, increasing treatment (particularly at the edge) resulted in higher areas of the landscape exposed to vegetation being burnt below its minimum tolerable fire interval.

In the Mt Lofty Ranges, we found complex patterns of risk are likely in the aftermath of the 2019-20 fires. In the absence of further wildfire events, risk of area burnt is likely to rise substantially by 2025, regardless of prescribed burning rates, with a similar result for vegetation exposed to too frequent fire. However, risk sto life, property and infrastructure are projected to remain similar to current levels.

Our work contributes to the evidence base for prescribed burning planning in South Australia, with future work potentially examining new management values (e.g. smoke health costs, new biodiversity measures) and exploring empirical relationships between prescribed burning and fire-affected area in 2019-20.

}, keywords = {black summer, kangaroo island, mitigation, Mount Lofty Ranges, Prescribed burning, risk}, issn = {690}, author = {Hamish Clarke and Brett Cirulis and Owen Price and Ross Bradstock and Matthias M. Boer and Anthony Rawlins and Trent Penman} } @article {bnh-8190, title = {Soil and fuel moisture precursors of fire activity during the 2019-20 fire season, in comparison to previous seasons - Black Summer final report}, number = {686}, year = {2021}, month = {08/2021}, institution = {Bushfire and Natural Hazards CRC}, address = {MELBOURNE}, abstract = {

Australia experienced unprecedented bushfires during the 2019-20 fire season. Millions of hectares were burned, almost 3,000 homes were destroyed, there were 26 fatalities, and communities were exposed to smoke for extended periods.\  Low soil and vegetation moisture content due to antecedent dry conditions were a key driver of fire activity.

This report extends the work in two Bushfire and Natural Hazards CRC projects to examine the 2019-20 fire season:

The national spatial datasets produced by these projects are consistent and regularly updated, separately examining soil and vegetation moisture variability, as both quantities influence fuel availability and therefore fire behaviour.

This project explores the overlaps between these data sets, as well as comparing other available data (including the Australian Landscape Water Balance) to identify atmospheric, soil and fuel moisture characteristics that contributed to fire risk during Black Summer.

Spatially coherent historical and regularly updated soil and fuel moisture datasets are critically important to fire managers so that an accurate, quantifiable assessment of potential fire activity in the landscape can be made, and this can be benchmarked against historical conditions. This information is crucial to making accurate assessments of risk and identifying situations that fall outside of historical records. One of the valuable aspects of JASMIN is that it can also be used in a predictive way and is therefore useful in anticipating soil moisture and therefore fire risk into the future in a quantitative manner on weather (short-term) and seasonal timescales. Research work in the {\textquoteright}Land Dryness{\textquoteright} project also demonstrated the capacity of soil moisture to predict future vegetation moisture content and thus more directly anticipate fire potential.

This project examines the interaction of atmospheric parameters with soil and fuel moisture content over scales of days, weeks to months, and years. Such an integration has not been undertaken previously.\ Consideration of each of these timeframes is important when making accurate assessments of fire risk. The interaction between them is also critical, as a compounding of the individual processes at the different scales occurs and this was seen in the cumulative effects of antecedent dry years, low winter rainfall and heatwaves during the Black Summer.\ 

This project examined six fire events that were nominated for investigation by the relevant jurisdictions. The fires are:

The scope of the project included examining the following:

Key findings of the project include:\ 

The findings confirm impressions of fire practitioners regarding the extremity of conditions antecedent to the 2019-20 fire season. Importantly, the datasets used in the project present a measurable and spatially coherent approach to estimating fire risk from observed and modelled soil and fuel moisture. Operational application of the datasets and approaches used here will assist in producing accurate soil and vegetation moisture forecasts for prediction of fire risk in the future.

Some immediate benefits for fire managers of this work include:

Each of the meteorological and moisture variables investigated in this study contributed useful information to an understanding of increased fire risk at each site during the 2019-20 Australian summer. Fuel moisture content provided perhaps the most immediate indicator of present fire risk. Soil moisture content permitted an assessment of future changes in fuel moisture content. Both of these integrated changes in meteorological parameters. As such, the meteorological parameters (temperature, precipitation, atmospheric moisture represented by vapour pressure) contributed an understanding of why soil and fuel moisture changed in the ways that they did and offered information on how they would change in the future. Monitoring these quantities can help fire and land managers understand how and why fire risk changes across a landscape.\ 

Future work

This project was conducted over a short time period with one objective being to establish a pathway for future research and operational application.

The following opportunities for future research with likely operational benefits have been identified:

In summary, better understanding and spatial mapping of the influence of atmospheric, soil and fuel moisture will assist fire and land managers predict fire risk, which is critical for strategic and tactical planning. Many of the recommendations could be inclusions to the Australian Fire Danger Rating System (AFDRS), and therefore of immediate benefit to fire and land managers following the introduction of the AFDRS to operational use over the next two fire seasons.

}, keywords = {black summer, Fire, fire activity, fuel, moisture, precursors, soil}, issn = {686}, author = {Paul Fox-Hughes and Marta Yebra and Shukhrat Shokirov and Vinod Kumar and Dowdy, Andrew J and Pandora Hope and Mika Peace and Sugata Narsey and Francois Delage and Huqiang Zhang} } @article {bnh-8191, title = {Wind speed Reduction Factors (WRFs): utilities for WRF assessment and communication - Black Summer final report}, number = {688}, year = {2021}, month = {08/2021}, institution = {Bushfire and Natural Hazards CRC}, address = {MELBOURNE}, abstract = {

This project commenced in March 2021 as a Bushfire and Natural Hazards CRC Black Summer funded initiative between Queensland Fire and Emergency Services and the School of Earth and Environmental Sciences at the University of Queensland. The purpose of the project was to undertake an evaluation of WRFs used in Australia (including during Black Summer) to quantify the reduction of open space wind speed by Australian fuel types.

Wind is a key driver of fire behaviour and can be highly variable and difficult to predict, particularly within the lowest 1-2km of the atmosphere where it interacts in complex ways with topography and vegetation. Operational fire spread modelling quantifies the impact of vegetation or fuel type on wind speed using Wind speed Reduction Factors (WRFs) or Wind Adjustment Factors (WAFs). Specifically, these factors quantify the impact of vegetation on reducing the speed of the open space prevailing wind. WRF is typically the ratio of 10m open wind speed to 2m wind speed, whereas WAF is the ratio of {\textquoteleft}midflame{\textquoteright} wind speed to 20 ft open wind speed.

To date, single or static WRFs have been assigned to 62 Queensland Broad Vegetation Groups (BVGs) for use within the operational fire simulation application PHOENIX Rapidfire. These WRFs have been derived via approximation. Specifically, the 10m open wind speed has been approximated by the closest Bureau of Meteorology (BOM) Automatic Weather Station (AWS) to the field site, and the 2m near-surface wind speed has been approximated via the use of a handheld anemometer raised to eye-level at a suitable location within the field site.

The key research aims were to:

The review found that the use of approximated static WRFs has caused minor to significant error accumulation in the fire spread model outputs produced by fire simulation applications, including PHOENIX Rapidfire.

To reduce error in fire spread modelling, the review concluded that the development of dynamic WRF modelling capabilities should be a priority. These dynamic WRFs should respond to key wind, fuel, fire and topography parameters that change over time and space.

However, a dynamic WRF model should not require such high levels of computation so as to delay real-time fire spread modelling outputs. At its simplest, a dynamic WRF model is a discrete, empirically derived WRF profile, illustrating the change in WRF at specific heights measured within a fuel type in the field. A more advanced dynamic WRF model might be a mathematical model for which wind, fuel, fire and topography parameters act as inputs and a mathematically idealised continuous WRF profile is the output. This model should be validated by empirical data. Overall, each fuel type should have its own WRF profile. The end goal should be to replace all static WRFs with dynamic WRF profiles in fire spread models.

A WRF test site was established in the priority fuel type {\textquoteleft}moist to dry eucalypt woodland on coastal lowlands and ranges{\textquoteright} at the Queensland University of Technology (QUT) Samford Ecological Research Facility (SERF), located on the outskirts of Samford Valley in Southeast Queensland. Installed at the site is a 15m instrumented tower using 3D sonic anemometers to record mean 3D wind speed, vertical wind direction and sonic air temperature. A discrete WRF profile was derived by taking the ratio of the average 10m open wind speed measured by the nearest BOM AWS in Brisbane and the average wind speed measured at heights of 2.5m, 4.5m, 10.5m and 15.5m. This WRF profile is preliminary as it is based on 23 hours of data collected outside the southeast Queensland fire season (August {\textendash} December).

Preliminary investigations of relationships between variables related to WRF were also conducted. The overall wind profile was compared to the Plant Area Density (PAD) profile of the vegetation obtained via terrestrial LiDAR (Light Detection and Ranging). A weak to moderate relationship was identified (R2 = 0.22) between mean wind speed and PAD, which may be due to the calm conditions experienced over the short length of the data collection period. Additionally, the day-time and night-time subcanopy temperature profiles were compared. The day-time profile was found to be slightly more constant with height, which may indicate that the subcanopy environment is more mixed and turbulent throughout the day. This result was supported by increased measurements of vertical mixing throughout the day. Nevertheless, data collection over a longer period under more varied conditions is recommended to investigate these relationships further.

The WRF test site at the QUT SERF has provided a preliminary insight into the relationships between vegetation and meteorology in the Australian context, which is essential for the development of empirically based dynamic WRF profiles for all fuel types. The methodology used is transferable and will be applied to other sites containing other priority fuel types. Anemometer measurements and LiDAR scans may then be used as key datasets for underpinning and validating the development of advanced dynamic WRF modelling capabilities in the next generation of fire spread models. Until this capability is developed, the new quick-reference WRF profile assessment resource developed by this project will enable FBANs near the fire ground to quickly identify the WRF values most relevant to the ensuing fire spread. These values may then be communicated to fire spread modellers.

}, keywords = {assessment, black summer, communication, factors, reduction, speed, wind}, issn = {688}, author = {Hamish McGowan and Katherine Rosenthal and Raymond Bott and John Myles} }