Bushfire Hazard Assessment

Bushfire Hazard Assessment
14 Serenity Close, Noosa Heads




4 BUSHFIRE HAZARD
Bushfire prone areas in Queensland are identified, mapped and categorised as a function
of potential fireline intensity (kW/m). Potential fireline intensity is a function of fire
weather severity (FFDI), landscape slope and fuel load based on classified vegetation
communities according to the method described by Leonard et al. (2014) (Refer to Figure
4).




                                   Fire                                              Fireline
                                                         Potential
      Slope                      Weather                                            Intensity
                                                         fuel load
                                 Severity                                             (PFI)



FIGURE 4: METHOD FOR CALCULATION OF POTENTIAL FIRELINE INTENSITY (PFI) (LEONARD ET
AL. 2014).




Areas of potential fireline intensity include potentially hazardous vegetation that could
support a significant bushfire or be subject to significant bushfire attack. It includes
potentially hazardous vegetation with a Medium (4,000 – 20,000 kW/m), High (20,000 –
40,000 kW/m) or Very High (40,000+ kW/m) Potential Bushfire Intensity. Bushfires in
these areas have the potential for high to extreme levels of flame attack, radiant heat and
ember attack. Land adjacent to bushfire prone areas is also at risk of significant bushfire
attack from embers, flames or radiant heat. The latter are identified as potential impact
buffer areas and include all land within 100m of areas mapped as Medium, High or Very
High Potential Bushfire Intensity. Together, the areas of potential fireline intensity and
potential impact buffer form bushfire prone areas.

Vegetated parts of the landscape which support fireline intensities of less than 4,000
kW/m are categorised as grassfire prone areas or low hazard areas (e.g. rainforest or
water or non-vegetated urban areas).

The SPP methodology was developed to overcome limitations of the approach adopted
by the previous State Planning Policy (SPP 1/03), including the failure to consider regional
differences in fire weather severity, effective slope and the diversity of vegetation types
and fuel loads across Queensland (Leonard and Blanchi 2012). The new methodology
estimates the potential fireline intensity at the landscape scale. Fireline intensity is a
standardised measure of the rate that an advancing head fire would consume fuel energy
per unit time per unit length fire front (Byram 1959). As noted by Leonard et al. (2014), the
benefits of utilising fireline intensity as the principal measure of bushfire hazard, is that it
can also be used to estimate the potential flame length (e.g. Alexander and Cruz 2012)



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