the february 2009 fires - 2009 Victorian Bushfires Royal Commission

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2009 Victorian Bushfires Royal Commission—Interim Report 1 THE FEBRUARY 2009 FIRES Table 1.1: Comparison of fire weather estimates for 15 and 16 February 1983 and 7 February 2009 Forest location Temp Relative Humidity % Wind Dir Wind speed Wind change Swan Hill 42 10 N 15 Swan Hill 42 10 N 25 Swan Hill 46 5 NW 40–65 SW 35 18–22 Hamilton 35 15 N 20 Hamilton 40 10 N 45 Hamilton 40 13 WNW 45–70 W 40 11–15 Bendigo 37 15 N 15 Bendigo 37 15 N 30 Bendigo 37 15 N 45–75 WSW 35 17–21 Ballarat 34 15 N 20 Ballarat 38 10 N 45 Ballarat 41 6 WNW 50–80 W 40 15–19 Shepparton 39 10 N 15 Shepparton 39 10 N 30 Shepparton 42 4 NW 45–75 SSW 30 20–00 Mangalore 38 15 N 15 Mangalore 39 15 N 30 Mangalore 43 5 NW 45–70 S 30 19–23 Melbourne 34 15 N 15 Sea breezes pm Melbourne 39 10 N 45 Melbourne (Tullamarine) 44 7 NNW 55–85 W 35 16–20 Orbost 34 20 NNW 15 Sea breezes pm Orbost 38 15 NNW 30 Orbost 40 14 NNW 20–40 SSW 35 20–00 Forecast issued at 17:00 hrs on 15/02/83 for 16/02/83 Forecast issued at 10:30 hrs on 16/02/83 for 16/02/83 Forecast issued at 14:45 hrs on 04/02/09 for 07/02/09 Source: Exhibit 3 – Statement of Rees (WIT.004.001.0001) at 0067 48 44
The February 2009 Fires Fire Behaviour 1.24 1.25 1.26 1.27 Fire behaviour results from the interaction of fuel, weather, topography and the fire itself. Overlaying this basic framework is a direct link between drought, increased fire activity and more intense fire behaviour. 49 This summary of the fire behaviour on 7 February is drawn largely from the evidence of Dr Kevin Tolhurst, senior lecturer and researcher at the University of Melbourne. The weather conditions leading up to 7 February, and the combination of the drought and the heatwave, led to increased combustibility and volatile fire behaviour because many of Victoria’s normally moist forests were dry. 50 These forest fuels carried the fire more easily than ordinarily expected. In turn, this led to fires of exceptional severity. So the conditions leading up to 7 February not only dried out Mountain Ash forests, which ordinarily would have been too moist to burn, but also added additional fuel loads to these forests. 51 Areas of bush had also died due to the cumulative effects of the drought over preceding years. Mr David McGahy, the Arthurs Creek-Strathewen CFA Brigade Captain who has lived in the area for 40 years, observed: … [the bush] was dying because of the cumulative effect of all the dry years. It was in a lot of trouble, the bush. I remember talking to one of the DSE chaps and he said, ‘If we cop a fire through here, it’s had it, this bush. It’s not going to regenerate because it is under too much stress now.’ So it was extreme. The week before we had had two or three days of 45 and it was just extreme. We knew if it came, it was going to be something special. 52 1.28 1.29 1.30 The fine fuels were desiccated by the conditions and they added again to the fuel load. Fine fuels respond much more to the short-term conditions such as the temperature, relative humidity and local wind conditions. Woody fuels — twigs, branches and fallen leaves — add to the heat coming off the burnt area. They also add considerably to the heat in the main convection column which, in turn, drives the fire. Normally those woody fuels burn behind the firefront and do not contribute much to the nature of the fire. However, when there is a large fire, under these dry conditions, they can add considerably to the convection column, which influences the whole firefront. 53 The fires of 7 February did not progress in a single, easily distinguishable line — there was a ‘fire zone’ that extended kilometres ahead of the firefront. 54 As described in the paragraphs below, this zone contained spotting that started further fires, which in turn burnt some areas well ahead of the main firefront. Subsequently, the main firefront passed over the same areas, further burning any remaining fuel. This process expedited the progress of the fires. The fires varied in description and behaviour: ■■ ■■ ■■ ■■ classic grass and scrub fires in western Victoria conventional bushfires progressing from ground fires to flame heights of 30(+) metres 55 extensive spotting directly sighted 13–14 kilometres ahead of firefronts and estimated up to 35 kilometres ahead of firefronts, with greater spotting over shorter distances, causing additional fires to ignite 57 spot fires further from the firefront, burning in the direction of the prevailing wind, while spot fires closer to the main firefront burnt back towards the fire. 58 56 45
Page 1 and 2: THE FEBRUARY 2009 FIRES 1
Page 3 and 4: The February 2009 Fires Source: AAP
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Page 49 and 50: The February 2009 Fires Figure 1.21

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