This project was commissioned and funded entirely by the Department of Environment, Land, Water and Planning, Victoria. 

In Australian fire history, large fires can have important environmental, social and economic consequences (e.g. death and injuries, destruction of buildings, crops and infrastructure). The impacts of these fires are often severe in rural/urban environments where large populations abut extensive tracts of flammable vegetation (Chen and McAneney, 2004). Examples of the destructive nature of bushfires are the Hobart fires of 1967, the Ash Wednesday fires throughout Victoria and South Australia in 1983, the Canberra fires of 2003 and, most recently, the Victorian fires in 2009 (the worst natural disaster in Australia’s history).

Fire danger rating systems (FDRS) are used to assess the potential for bushfire occurrence, fire spread and difficulty of suppression (McArthur 1967; Sharples et al. 2009). Although many examples of fire danger ratings (and indices) exist, the McArthur fire danger meter is the widely used index in south eastern Australia (Noble et al. 1980; Sharples et al. 2009) where the greatest losses of life and property have occurred. This McArthur index is a tool for broad fire danger rating, and is used to declaring fire bans, informing people of the risk of fire, and for planning and allocating resources (McArthur 1967; Sharples et al. 2009). Bushfires exhibit spatial and temporal patterns of occurrence and resulting damage. Spatially variable factors such as slope, aspect, ignition patterns, fuel characteristics and fire weather all contribute to the overall threat posed by bushfire (Chandler et al. 1983). Therefore, the McArthur index is related to the flammability of fuels and the rate of fire spread under different fuel dryness and meteorological conditions. Although the McArthur FDRS has been in use for over 50 years, there are some inherent weaknesses in the underlying system, and does not fully meet contemporary needs.

While the McArthur FDRS has been an essential component of fire danger warnings in Australia, it makes more sense that a fire danger rating system should reflect how fire behaviour characteristics determine not only difficulty of suppression, but also the potential for damage to a community and other assets – much like the Richter scale for earthquakes. A need for such a change in research direction largely stems from the fact that no consistent framework exists for describing the damaging potential of bushfires, and yet, recent evidence by Leonard and Bowditch (2003) showed that the costs to human lives, property and natural resources were increasing.

To date, very little exploratory research has been conducted to investigate the relationship between fire danger rating systems and community loss. To fill this gap, this study and report on the fire severity scale, commissioned by the Victorian (then) Department of Sustainability and Environment and the Victorian Department of Justice (Harris et al., 2011) provided valuable insights into the relationship between fire danger and community loss by testing a new framework for a fire severity scale based on the rate of energy release (power) and community loss.

A new fire danger rating system is required that is able to link the potential for fires to start, spread and cause damage with traditional fire agency needs such as prevention and preparedness planning, with end to end knowledge about how threat to communities and their assets.  For this to occur, a contemporary fire science research agenda is required.  Additional research that improves the understanding of the destructive potential of future bushfires and the ability to predict community consequences is essential. This includes better understanding of the aspects of fire weather and fire behaviour such as fire categorisation, fire and atmospheric interactions, fuel categorisation and better prediction of thresholds that lead to impacts on communities and the things they need and value.

 AIM AND OBJECTIVES

This project aimed to explore the relationship between fire behaviour indices/measures of fire strength and community loss; and, initiate possible fire severity scales through the use of a national archive of past bushfires and their impacts on communities. This aim was achieved through the following steps:

• Collate data building upon existing fire behaviour related information on the impact of major fires in Australia in relation to community loss
• Review and calculate fire behaviour indices, fire intensity and the power of each fire
• Determine and analyse the relationship between fire behaviour indices, fire intensity and the power of fire with community loss