Bushfires of low or moderate intensity often pose little threat to life, property and community assets. However, bushfires that burn in heavy fuels, steep terrain or on hot, dry and windy days often spread rapidly, crown in forests, produce powerful convection columns and create extensive spot fires ahead of the fire front, often making their control impossible until weather conditions moderate.
As the AFAC Bushfire Community Safety Position Paper states: Bushfire loss can be reduced or avoided in some cases, but cannot be entirely prevented. A balance needs to be struck between measures taken to reduce or avoid harm and loss due to bushfire, and the protection of other values. This compromise involves acceptance of the inevitability of some loss of life, property, infrastructure and community assets.
Understanding risk and treatment options
One of the best ways to establish and treat risk is ISO 31000:2009 the International Standard for Risk Management gives a list in order of priority on how to deal with risk:
- Avoiding the risk by deciding not to start or continue with the activity that gives rise to the risk
- Removing the risk source (managing or reducing bushfire fuels)
- Changing the likelihood
- Changing the consequences
- Sharing or transferring the risk with another party or parties (such as insurance)
- Retaining or accepting the risk by informed decision
- This list should be the path that people follow to mitigate risk. It is possible to remove risk entirely but in many cases it is too costly or is simply in achievable.
- For example society could prevent deaths in motor vehicles by removing them from the road. There are a bunch of opportunity costs associated with this and in the end society establishes acceptable practice or acceptable losses.
The same approach applies to bushfire mitigation. There are a range of strategies through the PPRR (planning, prevention, response and recovery) spectrum.
Working bottom (I have taken a pretty simplistic approach) up from the list
- Recovery picks up the pieces when the risk is realised, i.e the fire burns through.
- Response or suppression is to deal with the risk as it is happening including issuing warnings.
- Prevention is undertaking measures to reduce the likelihood of fires starting and spreading such as arson programs, education, fuel management including selective fuel management near to asset and fuel management burning.
- Planning to remove the threat or incorporate resilience principles. Ie good planning approvals and local planning processes and incorporating modern construction levels into new development in accordance with AS3959.
- The best approach is always from the top of the list so the best bang for the buck is to do appropriate planning and development control. If subdivisions are designed correctly then the infrastructure (ie road with design and layout, water and services are underground) is effectively in place forever. One of the options is not to allow subdivision or vulnerable development (i.e. schools, hospitals, aged care) that does not meet minimum planning requirements for bushfire protection.
Where an expectation arises out of an entitlement to build or where an existing house is being renovated, AS3959 can be used to determine the Bushfire Attack Level and apply appropriate construction levels.