Wind–terrain effects on the propagation of wildfires in rugged terrain: fire channelling
Jason J. Sharples A B E , Richard H. D. McRae B C and Stephen R. Wilkes D
+ Author Affiliations
- Author Affiliations
A School of Physical, Environmental and Mathematical Sciences, University of New South Wales at the Australian Defence Force Academy, Canberra, ACT 2601, Australia.
B Bushfire Cooperative Research Centre, Level 5, 340 Albert Street, East Melbourne, VIC 3002, Australia.
C ACT Emergency Services Agency, GPO Box 158, Canberra, ACT 2601, Australia.
D Fire Management Unit, ACT Parks, Conservation and Lands, GPO Box 158, Canberra, ACT 2601, Australia.
E Corresponding author. Email: j.sharples@adfa.edu.au
International Journal of Wildland Fire 21(3) 282-296 https://doi.org/10.1071/WF10055
Submitted: 17 May 2010 Accepted: 25 May 2011 Published: 23 January 2012
Abstract
The interaction of wind, terrain and a fire burning in a landscape can produce a variety of unusual yet significant effects on fire propagation. One such example, in which a fire exhibits rapid spread in a direction transverse to the synoptic winds as well as in the usual downwind direction, is considered in this paper. This type of fire spread, which is referred to as ‘fire channelling’, is characterised by intense lateral and downwind spotting and production of extensive flaming zones. The dependence of fire channelling on wind and terrain is analysed using wind, terrain and multispectral fire data collected during the January 2003 Alpine fires over south-eastern Australia. As part of the analysis, a simple terrain-filter model is utilised to confirm a quantitative link between instances of fire channelling and parts of the terrain that are sufficiently steep and lee-facing. By appealing to the theory of wind–terrain interaction and the available evidence, several processes that could produce the atypical fire spread are considered and some discounted. Based on the processes that could not be discounted, and a previous analysis of wind regimes in rugged terrain, a likely explanation for the fire channelling phenomenon is hypothesised. Implications of fire channelling for bushfire risk management are also discussed.
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