The brief was to present my views on the recent wildfires (bushfires) that ravaged parts of California, USA; Algarve, Portugal; and around Athens, Greece and what we might learn from those fires.
In doing so I sought to mention a broader context of loss due to wildfire:
• human life
• pets and other domesticated animals
• family home
• sources of income e.g. tools of trade, farm animals, crops
• consequential effect on relationships in the family suffering loss
• consequential medical issues associated with suffering loss
Since Saturday while research wildfire information from the US I've added two more, important issues for another day:
• deleterious effect on the natural environment
• avoidable impost on the public purse
Recent fires in North America, Portugal and Greece … what lessons for Australia?
Having the benefit of spending time with forestry and fire agencies in Canada and the USA and being a long term student of fire behaviour and community responses generally I do have some understanding of wildfires and their impact in North America.
Concerning the fires in Algarve and Greece, in places the vegetation is similar to South-eastern Australia and the wildfire problem is similar to ours.
Currently we Victorians have the potential benefit of the following to mitigate wildfire loss:
• A “pecuniary interest” clause in the Country Fire Authority Act 1958 (CFA Act) that prevents people being forced to evacuate in the event wildfire does or may threaten their home;
• A provision in the CFA Act that enables the serving of “fire prevention notices” to abate fire hazards on private land;
• A provision in the CFA Act that places fire prevention or mitigation responsibilities on municipalities and public authorities;
• An Australian Standard for construction in wildfdire-prone areas: AS 3959; and
• CFA volunteer brigades embedded in much of the urban/rural interface and beyond enabling actual community involvement in emergency management.
Lessons for us?
The folly of widespread evacuation, be it voluntary or mandatory evacuation orders issued.
Why folly? See what remains unburnt and not even scorched in Plates 2 and 3 and I’m referring to the vegetation.
The vegetation that remains undamaged is due to it being beyond flame contact and radiant heat sufficient to scorch that vegetation.
How wildfire travels across the landscape
Basically, fire travels across the landscape by igniting the fine fuel or vegetation such as dry grass, fallen dead leaves and twigs up to pencil size. Depending on the dryness of the heavier fuels such as dead-and-down tree limbs the fine fuel acts as “kindling” for the heavier fuels.
Nature of the fuel or vegetation in California compared with South-eastern Australia
The vegetation where the recent fires have occurred can be broadly described as grassland, chaparral and conifer forests i.e. pine and cypress trees.
Heath land in Victoria, such as that shown in the following two photographs, is similar to chaparral:
Plate 10 is included to show the difference between pines and our native eucalypt trees. As shown in Plate 9 pines burn vigorously when ignited and like eucalypt species contain volatiles. However, unlike eucalypt canopies that tend to have significant gaps between the canopy and surface fine fuels or "kindling", pine and cypress tree canopies tend to be closer to the ground and compact compared to eucalypts.
Following are a series of photographs I've taken over the years following fires that have involved trees and shrubs in Victoria.
Plate 11 is a view of Firth Park in the Lerderderg State Park a few days after the "Ash Wednesday 1983" fire showing an absence of "crown" or tree canopy fire in the forest in the background. Note the singed trees or shrubs in the foreground.
Plates 12 and 13 are further south from Firth Park towards Bacchus Marsh.
What is particularly significant about Plates 12 and 13 apart from the lack of crown fire? The unburnt shrubs/suckers at the base of the trees!
Below from my blog posting of 22 June 2014 are two examples of trees and shrubs in the path of the 9 February 2014 Gisborne fire as it travelled northeast towards Riddells Creek after the wind change.
The fire weather conditions this day were described as being the worst since 7 February 2009 (Black Saturday). Again, observe the vegetation close to the ground left unburnt when the fast moving grass fire passed.
Plate 15 is particularly significant in that cypress trees along the fence line were only scorched.
The arrow in Plate 16 points to a gap in the tree canopy that reveals undamaged eucalypt tree canopies in the background that were certainly in the path of the fire. Those eucalypts are on one of the higher points on the western side of Skyline Road.
Apart from heath and low scrub, the evidence is that crown fire is a relatively rare occurrence in the Victorian wildfire environment compared with how fire moves across the landscape in California. Unfortunately, the fires in California, Algarve and Greece featured large in Australian media and undoubtedly served to frighten lay people — counterproductive to building a wildfire resistant community.
Why then the loss of dwellings?
Plates 2 and 3 show unburnt vegetation around the remains of dwellings, and far more numerous than shown here. The unburnt vegetation tells us that consistent flames and radiant heat sufficient to ignite did not reach these dwellings.
The evidence suggests they were ignited by windborne embers from fire further distant. The reason for this ignition can vary, but one cause may have been embers landing on easily ignited bituminous roofing tiles preheated by the heat of the day plus hot air from the fire. Another cause may have been embers landing in vegetative mulch and igniting flammable vegetation close to windows, the glass eventually breaking and allowing fire to reach inside the dwelling.
This fire had also developed into what some may refer to as a "fire storm" with wind so strong as to damage the dwellings and allow ember penetration.
Plate 17 is the current pre-fire photo of the land shown in Plate 1. There is nothing dramatic about the vegetation shown and if nothing had changed there was vegetation removal at the rear of the western side of the development and a much broader clearing to the north to inhibit flame contact and dangerous radiant heat reaching the dwellings.
The two yellow arrows point to backyard swimming pools that are points of reference for those who want to go exploring with Google Street View — views towards the west from further north along Buenaventura Boulevard show the vegetation involved.
How wildfire arrives
Windborne embers and firebrands are the major method of fire spread by igniting fresh fuel ahead of the main fire front. This process is known “spotting”, as in the lighting of “spot fires” or fires starting in separated spots ahead of the fire front. To be a threat, this burning material must be sufficiently light in weight to be carried by wind while continuing to flame or smoulder sufficiently long enough to ignite fresh fuel.
I categorise “spotting” as follows:
The transmission of light burning or smouldering material generally horizontally above ground out to a distance of 100 metres and usually in the form of burning dead eucalypt leaves and other material of a similar weight picked up off the ground, and possibly the larger forms of grass seed heads or burning stringybark from tree trunks.
Stringybark eucalypts, where the bark has not been given a recent “haircut” — singed by fire leaving the bark tight against the trunk with little or no fine fibres available to be ignited — will shed sparks and embers as fire travels up the bark. In strong wind stringybarks can be a prolific source of embers over a relatively short distance until all the fibrous aerated bark has been consumed.
Long distance spotting commonly involves the bark from gum species eucalypts, some of which shed their bark in the form of long ribbons that are susceptible to being carried aloft in the convection column or updraft above the fire. These ribbons of bark are generally aerodynamically shaped and consequently carry further in the upper wind. Due to their size they can remain alight for some time before falling to the ground and starting new fires, sometimes several kilometres downwind from the main fire. Plate 18 shows examples of gum bark ribbons.
Wye River–Separation Creek, Christmas Day 2015
Plate 19 shows spot fires burning under the influence of upslope in the absence of wind. The spots were due to gum bark firebrands further north following the break-out of the Jamieson Creek fire that occurred on 19 December 2015.
Plate 20 shows the aftermath of the Christmas Day fire, with scorched tree canopies and virtually no true "crowning", but 116 houses lost in Wye River–Separation Creek. Plate 21 show the effect of the fire on vegetation on the high side of Karingal Drive where there were many houses lost.
Why only scorching as shown in Plates 11, 12, 13, 14, 15, and 21? My opinion is that there was insufficient surface fine fuel or "kindling" under those trees and shrubs to provide sufficient heat to dry the foliage to the stage where it would actually burn.
Anglers Rest, Victoria, 2003
Here is an example of how fire crosses the land in an under-story fuel reduced environment. The video was recorded at Anglers Rest north of Omeo in January 2003 when the building was directly threatened — may take time to load but worth waiting. It shows some well prepared people protecting the building from fire in very windy conditions. The video shows fire moving past as "spot fires" that eventually join, but much of the fuel has been consumed by the time the "spots" join. Also note no "crowning".
I've since found the following of interest:
1. Concerning trees reducing wind speed
Following is an extract from an ABC News story:
2. Global warming and wildfire
A thought-provoking BBC podcast on the effect of global warming on wildfire "The Long Hot Summer, Heatwave" Episode 1 of 2.
Between 12 minutes and 17 minutes running time the podcast covers wildfire in California, USA, earlier this year and the believed impact of global warming, and note the comment "perpetual fire season" — some are referring to this as the "new normal". Some photos and comments on the Carr fire here
What does this mean for Australia? Given the early onset of fires in Eastern Victoria this year it seriously questions the appropriateness of the one-size-fits-all leave early message if life loss is to be prevented and property loss minimised.
Works in progress
There is more I would like to add, but this post is already too long. Consequently, I will follow this with another in the near future. Feel free to use the "following" facility in the side margin if you want to receive future posts.
Finally, please make your own inquiries about how much defensive space you need to have around your home or out-buildings, as individual circumstances vary according to slope aspect, vegetation type/s and the building's fire resistance capability. Also obtain CFA's literature dealing with bushfire survival, property preparation and leaving early.
While speaking about fire behavior I mentioned Bushfires in Australia, R.H. Luke and A.G. McArthur.
My copy is old: Department of Primary Industry,Forestry and Timber Bureau, CSIRO Division of Forest Research, AGPS, Canberra, 1978. It is still current and I consider it a preeminent textbook for those wanting to learn about wildfire in Australia. It should still be available somewhere.
Meantime, if you have a question or comment please use the facility at the foot of this posting.
Note that the coloured text indicates links to further information to be clicked on.