Forest Ecology and Management xxx (2012) xxx–xxx Contents lists available at SciVerse ScienceDirect Forest Ecology and Management journal homepage: www.elsevier.com/locate/foreco Anatomy of a catastrophic wildfire: The Black Saturday Kilmore East fire in Victoria, Australia ⇑ M.G. Cruz a, , A.L. Sullivan a, J.S. Gould a, N.C. Sims b, A.J. Bannister c, J.J. Hollis a,d,e, R.J. Hurley a a CSIRO Ecosystem Sciences and CSIRO Climate Adaptation Flagship, GPO Box 1700, Canberra, ACT 2601, Australia b CSIRO Land and Water, Private Bag 10 Clayton Sth, VIC 3169, Australia c Bureau of Meteorology, GPO Box 1636, Melbourne, VIC 3001, Australia d University of New South Wales at the Australian Defence Force Academy, Canberra, ACT 2600, Australia e Bushfire Cooperative Research Centre, Level 5, 340 Albert Street East Melbourne, VIC 3002, Australia article info abstract Article history: The 7 February 2009 wildfires in south-eastern Australia burned over 450,000 ha and resulted in 173 Received 28 October 2011 human fatalities. The Kilmore East fire was the most significant of these fires, burning 100,000 ha in less Received in revised form 21 February 2012 than 12 h and accounting for 70% of the fatalities. We report on the weather conditions, fuels and prop- Accepted 28 February 2012 agation of this fire to gain insights into the physical processes involved in high intensity fire behaviour in Available online xxxx eucalypt forests. Driven by a combination of exceedingly dry fuel and near-gale to gale force winds, the fire developed a dynamic of profuse short range spotting that resulted in rates of fire spread varying Keywords: between 68 and 153 m minÀ1 and average fireline intensities up to 88,000 kW mÀ1. Strong winds aloft Megafire and the development of a strong convection plume led to the transport of firebrands over considerable Wildland–urban interface Crown fire distances causing the ignition of spotfires up to 33 km ahead of the main fire front. The passage of a wind Eucalyptus change between 17:30 and 18:30 turned the approximately 55 km long eastern flank of the fire into a Spotting headfire. Spotting and mass fire behaviour associated with this wide front resulted in the development Pyrocumulonimbus of a pyrocumulonimbus cloud that injected smoke and other combustion products into the lower strato- sphere. The benchmark data collected in this case study will be invaluable for the evaluation of fire behaviour models. The study is also a source of real world data from which simulation studies investigat- ing the impact of landscape fuel management on the propagation of fire under the most severe burning conditions can be undertaken. Ó 2012 Published by Elsevier B.V. 1. Introduction The fires that occurred on 7 February 2009 (colloquially known as ‘Black Saturday’), represent 44% of the fatalities. Of a total of 316 South-eastern (SE) Australia has a combination of climate, fires burning on this date, 13 developed into significant incidents topography and vegetation that makes it prone to severe wildfires. (Fox and Runnalls, 2009) and five resulted in 173 fatalities. The Kil- Fires occur in most years but are generally most extensive and se- more East fire was the most significant of these, resulting in 70% of vere following extended drought, typically associated with El-Nino the fatalities on the day. It burnt nearly 100,000 ha and destroyed events (Sullivan et al., 2012). This region has a long history of severe over 2200 buildings in the first 12 h alone. The fire eventually fire events, some of which have significantly influenced wildland merged with the Murrindindi fire, burning a combined area of fire control and land management policy. In the past seven decades approximately 400,000 ha over a period of 3 weeks. catastrophic fire events (defined here as fire in which at least a sin- Understanding the development and behaviour of the Kilmore gle day of high intensity fire behaviour occurs and generally results East fire is important for a number of reasons. It is a critical step in large area burned with significant destruction of infrastructure in identifying the factors that led to the scale of this catastrophic fire and loss of life) have impacted SE Australia in 1939 (Black Friday), and its unprecedented impact on lives, livelihoods and ecosystem 1983 (Ash Wednesday), 2003 (Canberra) and 2009 (Black Saturday). components. Despite the diverse adaptation of Australian ecosys- These four fire events have burnt 7.68 Mha of land and caused 390 tems to fire (Gill, 1981a,b), large-scale fires can have detrimental fatalities, predominantly in the state of Victoria. impacts on ecological values. Such a fire converts biodiversity-rich, fine-scale mosaics at a range of seral states into a less diverse landscape, both in terms of species composition and vegetation ⇑ Corresponding author. Tel.: +61 2 6246 4219; fax: +61 2 6246 4096. structure (Adams and Attiwill, 2011). The sustainable management E-mail address: [email protected] (M.G. Cruz). of SE Australian ecosystems requires a landscape level approach to 0378-1127/$ - see front matter Ó 2012 Published by Elsevier B.V. http://dx.doi.org/10.1016/j.foreco.2012.02.035 Please cite this article in press as: Cruz, M.G., et al. Anatomy of a catastrophic wildfire: The Black Saturday Kilmore East fire in Victoria, Australia. Forest Ecol. Manage. (2012), http://dx.doi.org/10.1016/j.foreco.2012.02.035 2 M.G. Cruz et al. / Forest Ecology and Management xxx (2012) xxx–xxx fuel management that mitigates the impact of catastrophic fire events. Sound knowledge of fire potential under extreme fire In the absence of any break in fuel or topography, isolated med- weather conditions is necessary to understand the effectiveness of ium-range spot fires are generally overrun by the main fire different land management strategies under similar burning front.When a pattern of concentrated medium range spotting conditions. develops, pseudo flame fronts (McArthur, 1967) lead to an Fire in eucalypt forests exhibit unique behaviour because of the immediate large increase on the overall rate of fire spread. Con- contribution of bark as a fuel (McArthur, 1967). Under extreme fire centrated medium range spotting can produce mass fire or fire- weather conditions bark fuels allow for profuse spotting dynamics storm effects (Luke and McArthur, 1978). In this situation a large (Box 1) that lead to very high rates of spread and occasionally fire- number of coalescing fires causes strong turbulent inflow circu- storm effects (Cheney and Bary, 1969). Quantitative knowledge of lation that results in high intensity burning.Long-distance spot- the processes driving these phenomena is lacking. Field-based fire ting (>5000 m) results from extended flight paths associated behaviour research in Australia has produced a number of models with significant lofting in a well-developed convection column (e.g., McArthur, 1967; Sneeuwjagt and Peet, 1985; Cheney et al., and long burn out times. This class of spotfire generally creates 1998; Gould et al., 2007a; Burrows et al., 2009) that are currently an isolated ignition that develops as a separate fire. Long range used to support forest and fire management activities. Nonethe- spotting of approximately 30 km has been authenticated in sev- less, data from these research programs only cover the lower 10% eral occasions in eucalypt forests (Hodgson, 1967; McArthur, of the fire intensity spectrum observed in wildfires (Cheney, 1967). Transport of firebrands over such distances requires À1 1991). Case studies documenting the propagation of large fires of- upper level wind speeds in the vicinity of 90–100 km h (Luke fer an opportunity to quantitatively describe fire behaviour at the and McArthur, 1978).The dynamics of high intensity fire propa- extreme end of the fire intensity spectrum (Alexander and Thomas, gation in eucalypt forests with fibrous barked species is charac- 2003). The objective of the present study was to describe the prop- terised by a self-sustained process with profuse short range agation and behaviour of the Kilmore East fire and gain insights spotting preceding the arrival/formation of a solid flame front into the physical processes determining the propagation of high involving the whole fuel complex.The distribution of ignitions, intensity fires in eucalypt forests. with density decreasing with distance from the flame front and rapid coalescence by interacting spot fires results in a grada- tion of area involved in combustion at any given moment. The Box 1.High intensity fire propagation in eucalypt forests. closer to the firebrand source the larger the area on fire. As the spot fires coalesce and more ignitions are generated the area There are notable differences in the mechanisms driving burning approaches a limit where the amount of released pyro- high intensity fire propagation in eucalypt forests to other lizates mixes with the air at a critical mixture that result in the fuel types such as conifer forests or shrublands. These differ- formation of a continuous flame front. The concept of a discrete ences arise from particular fuel complex characteristics in eucalypt forests. Most temperate eucalypt forests have fairly flame front separating unburned from burning fuels as observed open canopies (McArthur, 1967, Gill, 1997) that allow the in other fuel types such as conifer forest and shrublands is not development of an understorey layer of dominated trees, directly applicable in this case. What is observed is a continuous shrubs and/or herbaceous vegetation that provide vertical increase on the proportion of area burning until a continuous fuel continuity. In eucalypt fuel complexes the presence of flame front is formed. tree species with fibrous bark (e.g., Eucalypt obliqua, E. mar- ginata and E. macrorrhyncha) is a key factor driving fire behav- iour.