Att3 - Bushfire Report

Bushfire Hazard Assessment & Management Plan v1                                              NCES REF: J001061
Lot 7 on RP216403, Lot 394 on M371117, and Lot 650 on M37380 – 48-59 Kabi Road, Cootharaba




3.6 3.6Quantitative Modelling
Quantitative modelling of the potential bushfire conditions that may be experienced within the
VHC 8.1 tall open forest, VHC 9.1 open forest, and VHC 36.1 pine forest within the site and
adjoining parts of the site has been undertaken to assist in determining the suitability of the
development and any asset setback requirements.
The models used comprise industry standard bushfire equations which have been built into
the FPAA endorsed FLAMESOL computer model. FLAMESOL allows numerous input
variables to be adjusted including fuel loads, fire danger index, site slope and distance to
vegetation. FLAMESOL uses the following algorithms:
    •    Rate of Spread – McArthur (1973) and Nobel et al. (1980)
    •    Flame Length – NSW Rural Fire Service (2001) and Nobel et al. (1980)
    •    Elevation of Receiver – Douglas and Tan (2005)
    •    Flame Angle – Douglas and Tan (2005)
    •    Radian Heat Flux – Drysdale (1999), Sullivan et al. (2003) and Douglas and Tan (2005)
The FLAMESOL Minimum Distance calculator has been used and comprises an AS
3959:2018 Method 2 (Appendix B) based calculator which will determine standard bushfire
behaviour variables as well as the minimum distances required to achieve a range of different
radiant heat levels (represented by BAL's).
Fuel load inputs have been drawn from Planning for Bushfire Resilient Communities (QFES
2019) based on the calculated potential fuel loads for the following;
    •    VHC 8.1 (31 t/ha surface and near surface fuels and 35 t/ha total fuels);
    •    VHC 9.1 (21 t/ha surface and near surface fuels and 24.2 t/ha total fuels); and
    •    VHC 36.1 (23.8 t/ha surface and near surface fuels and 26 t/ha total fuels).
1º effective slope was adopted for the slope underlying the VHC 8.1 to the south/southwest,
VHC 9.1, and VHC 36.1 given across slope conditions underlying the vegetation. A 3º effective
slope was adopted for the slope underlying the VHC 8.1 to the southeast/east given the slight
downslope conditions underlying the vegetation.
The default Flame Width of 100m was chosen for all units precluding the VHC 9.1 unit in the
north-west which was assigned a Flame Width of 60m due to the reduced width of the unit.
A Forest Fire Danger Index (FFDI) of 47 has been adopted for the site consistent with the
assignment by QFES (Catalyst 2020) (refer Plate 13).




                                   Plate 13 – FFDI (Source: QFES redi Map)




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