Western Australia: Improving mitigation

How prescribed burning is making its (successful) mark

There’s been much debate in the news lately following the extensive bushfires in NSW and Victoria this summer of 2019/2020.

It would appear from examining the context of the fires that prescribed burning and other mitigation actions are not used to the same extent as has been happening in Western Australia for the past several decades or so.

Fire scientists have been very active in researching the causes and the management of bushfires and have published the results. Whilst the forests in south west WA are endemic to the area, the general principles discovered in the WA research can, with adjustments for different fire regimes, be applied in other bushfire prone areas of Australia.

Two of these bushfire researchers recently wrote the following essay which explains why we need to carry out prescribed burning wherever we have forests and woodlands. The authors are Neil Burrows and Rick Sneeuwjagt and here is their essay. A must-read.

Neil Burrows makes the keynote presentation at the AFAC Conference held in Perth in September 2018.

Out of frustration Rick and I have written the piece below to counter some of the nonsense that is circulating from people who have no understanding or practical experience with fire behaviour, prescribed burning and bushfire suppression. Between us, Rick and I have more than 80 years experience in bushfire science, policy, planning, prescribed burning and fire suppression. The piece is lengthy but its a complex issue.

How and why prescribed burning mitigates bushfire losses

Neil Burrows and Rick Sneeuwjagt

The piece by Byron Lamont and Tianhua He titled “Why prescribed burns don’t stop wildfires” (WAToday 22 January 2020) is complete fiction. It reveals that these authors have no experience or operational understanding of fire behaviour, prescribed burning and bushfire suppression. Their baseless and inhumane opinions, if given any credibility, will give rise to very dangerous fire management policies, a continuation of a cycle of devastating bushfires and further losses of lives and beautiful forests.
The title of their article is a clue to their lack of understanding. Prescribed burning is not designed to stop bushfires. It is designed to make them easier, safer and cheaper to suppress. Experienced land managers, fire fighters, and the bushfire scientists who work closely with them, are in no doubt that the scientific, experiential and historical evidence demonstrates that prescribed burning, done properly, is highly effective at mitigating the bushfire threat, even under severe weather conditions. This is based on the following evidence.
Firstly, fire science. Reducing fuel loads and simplifying fuel structures by regular burning reduces the speed of a bushfire, its intensity (heat energy output), the size of the flames and its ember and spotting potential. All of this makes bushfires less damaging and easier to put out. In mature forests, crown fires cannot be sustained if the surface and near surface fuels are at low levels as a result of regular fuel reduction burning.

Lamont and He make the extraordinary assertion that long unburnt forest fuels are of low flammability and therefore of no significant threat to communities. This is not only demonstrably untrue, it is dangerously wrong. For example, in long unburnt karri forest, much of the live, green understorey dies and becomes dead, dry fuel on the forest floor after about 25-30 years. Bushfires are most likely to occur well before that time. Dead scrub, together with accumulated dead leaves, twigs and bark, the surface and aerated near-surface fuels can be a meter or more deep with total fuel loads of up to 50 tonnes per hectare. In dryer stringybark forests, the sparser, lower understorey vegetation comprises a small component of the total fuel complex. It is the accumulation of dead fuels (leaves, twigs, branchlets, bark) that drives forest fires. This is because it is at the base of the ‘fuel ladder’, it is dry, and it reaches very high loadings if left unburnt.

Second, real-world experience. We know of hundreds of examples where prescribed burning has ‘saved the day’

. Hot fires ran into areas of low fuel, and the resulting reduced fire behaviour enabled fire fighters to gain the upper hand. Conversely, we can cite numerous recent examples where a lack of prescribed burning has resulted in unstoppable fires and considerable losses. Ask any fire fighter whether they would rather fight a bushfire in 4 year old fuels or in 40 year old fuels? We know what the answer will be. Academics like Lamont and He disdain the experience of bushmen and experienced firefighters, preferring computer models developed on a green, leafy campus. In doing so they reject the experience of real-world Australians and their experience over the last 200 years.

Third, history. There are almost 60 years of historical data from the forests of south west WA, and these data unequivocally show that when the area of prescribed burning trends down, the area burnt by bushfire trends up. There is a simple explanation: bushfires are more difficult to put out in heavy fuels. The area burnt by wildfire escalates rapidly when the area of prescribed burning in a region falls below about 8% per annum. Burning about 8% per annum results in about 40% of the bushland carrying fuels 0-5 years old.

A very powerful factor in the recent bushfire tragedies in NSW is the fact that prescribed burning in NSW has amounted to less than 2% per annum. This means only 10% of the bushland is carrying fuels 0-5 years old and 80% is carrying fuels older than 10 years. This is well below the threshold for effective bushfire mitigation because a high proportion of the region is carrying very old, heavy, flammable fuels. Fires in these fuels rapidly become unstoppable, especially when they have been dried out by years of drought.

Finally, strategic planning. To be effective, prescribed burning must also be strategic – that is, done in the right places to protect communities by intercepting fire runs under the worst fire weather conditions. The fire management cells need to be large enough to ensure a sufficient area for the spread of a bushfire to be slowed and controlled. Burns must be bounded by roads or tracks to enable rapid access by fire fighters. Burning must be done to appropriate standards of fuel removal and fire intensity. Prescribed burns that are too patchy may not slow a bushfire, and in some forests, burns that are too hot can stimulate the regeneration of dense scrub.

Prescribed burning – how and why it works
The purpose of a fuel reduction burning program is not to stop bushfires, but to assist with their safe suppression. The process of bushfire suppression is complex and dynamic. There are a variety of suppression strategies and tactics that can be used in space and time, depending on weather conditions, fuels, topography, fire behaviour, fire shape and fire position in the landscape, and fire intensity around the fire’s perimeter.
Fire fighters rarely make a direct attack on the head fire – it’s usually too ‘hot’. Instead, they implement other strategies including a variety of direct, indirect and parallel attacks – the options, and likelihood of early success, are greater if the fire is burning slower and at a lower intensity because it’s burning in young, light fuels. Appliances such as water bombers will be more effective on slower moving, lower intensity fires. Fire intensity varies around the fire’s perimeter, affording suppression opportunities – there will almost always be a place on the fire’s perimeter that can be attacked – even under severe fire weather conditions – and if fuel loads are low, this opportunity widens significantly.
The most trying bushfire situation occurs when there is wind shift and the long flank of the fire becomes a wide head fire. Therefore, containment work on the ‘pressure flank’ is critical and is more likely to succeed in young, low fuel situations when flank fire intensity is relatively low, even under severe weather conditions.

If part of the fire is burning in very light fuels as a result of prescribed burning, then if resources are stretched, it can be ignored and resources deployed to higher priority areas around the fire perimeter, or to defending properties, or dispatched to other fires in a multiple fire situation.

Prescribed burning provides ‘anchor points’ and ‘tie in’ points for fire fighters. These low fuel areas are very important for indirect suppression strategies including back burning. Attempting to back burn in old, heavy fuels against old, heavy fuels is a slow, resources demanding, dangerous and risky process. Back burning in young, light fuels surrounded by young, light fuels is much safer, more likely to be successful and requires less resources. Low fuel areas are also very important for ‘tying in’ containment lines, enabling faster, more efficient suppression. The speed of construction of containment lines is crucial in the battle against a growing fire. Fire suppression is a race in terms of rate of fireline construction and containment verses rate of perimeter growth of the bushfire. Fires burn slower in younger, lighter fuels, not only improving the likelihood of early detection and suppression, but increasing the odds of fire fighters getting the upper hand.

Severe fire weather fire weather conditions don’t last very long in the life cycle of a bushfire – when diurnal fire weather conditions ease (and they always do at some point), and if the fire is burning in young, light fuels, there is a larger window of opportunity for safe suppression, than if it’s burning in old, heavy fuels.

There are two other critical ways in which fuel reduction programs assist with bushcontrol. The first is that it allows fires to be suppressed in the lead-up days to extreme conditions. Firefighters are nearly always overwhelmed when ‘catastrophic’ conditions (i.e.hot, dry, windy weather) strike fires that are already burning in the landscape. The presence of low fuel areas makes it more likely that these fires can be controlled before the catastrophic conditions occur.

The second is that when there are multiple fires on the same day, as occurred during the Cyclone Alby crisis in WA in 1978, fire controllers can set up a “triage” response. Fires burning in 1 or 2 year old fuel can be temporarily ignored, while all the focus is placed on the most threatening fires. This allows the best use to be made of resources.

Regardless of fire weather conditions, to firefighters, fuel load matters. It directly affects fire intensity (heat energy output) around the fire’s perimeter, and the size of the suppression windows in space and time. Also, containment line break outs such as hop overs and spot fires, are much easier to control in light fuels than in heavy fuels.

The fuel load burning behind the flame zone, which is greater in older fuels, is critical for suppression difficulty because total heat output acts in a number of ways. It is an input to convection which increases wind speeds in the flame zone, boosting spotting and fire behaviour. It increases the likelihood of high energy release rates and deep flaming, conditions that can trigger a transition to a dangerous and unpredictable plume-driven fire. It increases the likelihood of re-ignition and breaching of the containment line by burning across it or by blown embers or by hop-overs. Radiation from glowing combustion adds to the heat load on firefighters and increases the time that the burnt ground can be used for safe refuge. It substantially decreases the effectiveness of water and other suppressants /retardants applied from the ground or from the air. Heavy fuel also hinders fire line construction and in some fuels make it impractical.

Of the elements that make up the bushfire triangle – fuel, weather and topography – only fuel can be managed. But this must be done the right way – underpinned by good science, well planned and well executed by trained, experienced people who are well resourced. Prescribed burning is costly and comes with an element of risk, but the alternative, a cycle of bushfires, is far more costly to communities and the environment.

Conclusion:

The article by Lamont and He in WAToday is not only factually incorrect, it is dangerous and inhumane. If the authorities were to take any notice of their assertions, and curtail the fuel reduction program, the result in WA would be identical to that currently occurring in NSW: death, destruction, heartbreak. Our advice to Lamont and He is to get some actual fire experience in the bush, get on the back of a fire truck, and then lets see what they think about the value of fuel reduction in assisting with bushfire control.

Neil Burrows sums up the pros and cons of prescribed burning at the 2018 AFAC Conference.

The Yarloop Primary School survived

It was no accident that the school survived

The Report into the Special Inquiry into the January 2016 Waroona Fire made mention several times that work had been done in the months before the Fire to reduce the fuel loads in and around the school buildings.

See Post of October 30, 2016:
https://firewisewa.me/2016/10/30/why-did-the-yarloop-school-survive/

Whilst the Report provided some information I wanted to know more of the details of the work done on the school and its grounds so contacted Phil Penny who was the Chief Fire Control Officer for the Harvey Shire. Mr Penny was also on the School P and C.

YP_21Mar16_IMG_3907

In the front area of the school grounds two months after the fire. Note that large fig (possibly a Moreton Bay) is relatively unscathed whereas the trees in the background are burnt. To the west of the school (toward the left of the image), several houses in School Road were destroyed, yet apart from one or two small sheds in the school grounds the buildings were intact.

Mr Penny sent me the details of the works to be done on the school. It was a straightforward document with photos of the areas that needed to have fuel reduced with descriptions of the actions to be taken. Here is the Bushfire Risk Inspection for Yarloop PS.

Bushfire Risk Inspection Yarloop PS

It’s worth a read as an example of the types of work that needs to be done, eg removing truckloads of debris made up of litter, fallen branches, dry grass, etc from certain areas.

Here is a quote from Mr Penny about this work to make the school safer:

“This is the original document I did up for Yarloop Primary School. Simple yet proved to be very effective. Work was carried out over about two months prior to the Bush Fire season and as we know the school survived. It just goes to show that the simplest of actions can be very effective in reducing risk and enhancing survival.Let me know what you think.”

I asked Phil the burning question (sorry) of “how much did it cost?”

Here is his reply:

“In the case of the school the cost ended up around $6000 which seems expensive but considering that they carted away a huge amount of fuel and mulch like material and tree loppers were utilised to trim trees it was an inexpensive investment in longevity for the school. Also all of this work was carried out by contractors to the school and the cost was afforded by Building Management and Works (BMW ) who look after maintenance for Government Infrastructure.
The ongoing maintenance is looked after by the School Gardner as part of normal duties ( except for any tree lopping ) and therefore ongoing costs are minimised.
For the average home owner most of this could be done by themselves and if need be burnt onsite at right time of year and therefore cost is minimal. Most people think that they have clear everyting to make it safe and I have proven this is not the case. They just need some direction which I provide.”

So you there you have it, for a small sum of $6000, the school was made to be at much lower risk from bushfire attack.

It is worth noting, too, that the school was undefended as the fire swept through. Thus it had been made to be self-defensible. Indeed it came through so well that it became the on-site location for the management of the clean-up effort, the Recovery process.

Would the outcome have been any different if, say, similar plans had been drawn up for the community centre, the Railway Workshops, the fire station and groups of houses?

If something of the order of  $100,000 had been spent on Yarloop in the months before the fire, the result may have been very different. Two men may not have lost their lives. 160 houses may not have been destroyed. At least $60 million dollars has been spent in the clean up.

What price safety? Instead of so much emphasis on response and recovery a program that assessed the small towns of the South West and spent a $100,000 on, say 10 towns each year, could bring huge savings.

It’s not just the money, of course. Democratic governments in civilised countries have a duty to keep their people safe. Australian citizens should not have to go through the terror of a fire like the Waroona Fire nor come back to the horror of their house and sheds burnt to the ground, their pets killed, their farm animals injured and dying.

We can do better. The bushfire risk reduction process carried out on the Yarloop Primary School is a shining example of the benefits and the sheer cost-effectiveness of these steps.

Let’s look at implementing these pre-emptive actions throughout the Perth Hills and the South West.

Why did the Yarloop School survive?

Many in Australia and overseas would be familiar with the bushfire that occurred in early January this year that burnt through thousands of hectares in the Waroona and Harvey Shires and caused a significant proportion of Yarloop to be destroyed.

Two people died in the Yarloop fire and over 160 houses were destroyed. The Government instigated a Special Inquiry into the January 2016 Waroona Fire. The Inquiry was undertaken by Mr Euan Ferguson AFSM. The Report titled “Reframing Rural Fire Management” was tabled in Parliament on Thursday 23 June 2016.

The Report is available on line at:
https://publicsector.wa.gov.au/waroona-bushfire-special-inquiry

This same web page provides links to the submissions made to the Inquiry. One of these submissions written by a member of the public, No 39, described why the Yarloop Primary School came out relatively unscathed despite being close to areas of the town that burnt intensely. There is an extract from this submission on Page 101 of the Report, which reads:

The Primary School remained standing throughout the fire. Although unattended as the fire passed, the school survived this was due to the fire Protection Plan developed by local fire experts – this plan included fuel reduction and separation of buildings from vegetation.37

The full submission is here and is from an experienced forester which sums up much of what needs to happen in advance of the heat of summer.

Submission of member of public No 39

yarloop_rose_22apr16_3953

In the grounds of the Yarloop Primary School a solitary flowering stem emerges from the base of a rose bush, scorched but still alive. 

If only we could develop robust systems as described in this submission to reduce the bushfire risk largely due to the build up of flammable vegetation across forests, grasslands and in towns, we could have a less stressful fire season. And no mass destruction of homes and farms.