Map 1 compares the extent of the 1983 Belgrave South bushfire with the extent simulated by PHOENIX Rapidfire, using 1983 fuel hazard levels and worst-case bushfire weather. The simulation shows the extent after 24 hours: the actual extent is the bushfire’s final perimeter. The map also shows simulated flame heights, which indicate the intensity of the bushfire. The map shows the accuracy of PHOENIX Rapidfire’s simulation of the location and extent of the bushfire. The differences between the actual and simulated bushfire extent are due to firefighters successfully controlling the actual bushfire by back burning in some areas, the actual bushfire burning longer than 24 hours in some areas, and on some local fire dynamics that the software does not account for. The Victorian Bushfire Risk Profiles report describes how DELWP uses PHOENIX Rapidfire to simulate bushfires, and to measure the effectiveness of fuel management in reducing bushfire risk. Bushfire scenarios PHOENIX Rapidfire simulation is based on worst-case bushfire weather, measured using the Forest Fire Danger Index (FFDI) which accounts for dryness (based on rainfall and evaporation), wind speed, temperature and humidity. The higher the FFDI, the more extreme the bushfire weather. On Black Saturday 2009—a day of extreme bushfire weather— the FFDI was recorded at over 130, which is the value DELWP uses for PHOENIX Rapidfire simulation of bushfire scenarios. History tells us a handful of extreme bushfires occurring on days when the FFDI is higher than 100 have caused the greatest losses of human life, although any bushfire (including those when the FFDI is much lower than 100) can destroy properties and claim lives. PHOENIX Rapidfire also lets us nominate the fuel hazard— the structure and amount of burnable vegetation—at any particular place. By altering the amount of vegetation in the landscape, we can use PHOENIX Rapidfire to simulate how fuel management may alter the behaviour of bushfires on days with FFDI 130. Simulated extent after 24 hours, showing flame height (m): 0–1 1–3 3–6 6–13 13–30 30+ Actual final extent Map 1: Actual and simulated extent of 1983 Belgrave South bushfire 0km 2km
Strategic bushfire management plan | East Central 7 Residual risk If there has been no fire—bushfire or planned burning—at a place, there is maximum fuel hazard. By reducing the amount of vegetation in places that bushfires are likely start, spread and impact, we can test the effectiveness of different fuel management strategies. The Victorian Bushfire Risk Profiles report has more information about how we use the PHOENIX Rapidfire bushfire simulation software to simulate bushfires and test fuel management strategies. When there is maximum fuel hazard, there is maximum risk a bushfire will damage or destroy a property or piece of infrastructure. Bushfires, and our fuel management strategy, reduce fuel hazard and so reduce bushfire risk.
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- Spring '15
- Aminul Islam
- Management, Bushfire, Black Saturday bushfires, Ash Wednesday fires