Development of the Victorian bushfire risk profiles and the concept of residual risk — ASN Events

Development of the Victorian bushfire risk profiles and the concept of residual risk (#66)

Andy Ackland 1 , Andrew Blackett 1 , Jaymie Norris 1 , Owen Salkin 2 , Gordon Friend 1
  1. Dept. Environment & Primary Industries (Vic.), East Melbourne, VIC, Australia
  2. Natural Systems Analytics, Noojee, Victoria, Australia

Bushfire risk is the likelihood of a bushfire starting, spreading and impacting assets and values of importance. The Department of Environment and Primary Industries (DEPI) carries out a range of activities to reduce the risk of bushfire on public land – including reducing forest fuels with planned burning and slashing – and is continually looking for more effective ways to achieve this. In recent years, DEPI, in collaboration with the University of Melbourne and the Bushfire Co-operative Research Centre, has invested in fire modelling software called Phoenix Rapidfire, which models the spread and intensity of a bushfire based on a number of variables. It can be used to show the likely effect of fuel reduction activities on bushfire risk. With the aid of Phoenix Rapidfire, DEPI has produced the Victorian Bushfire Risk Profiles Report using a range of inputs such as topography, fuel, vegetation types, bushfire history, fuel reduction history, private land vegetation and weather. Using Phoenix, DEPI modelled the start, spread and impact of hypothetical bushfires on human life and property, based on thousands of possible fire ignition points. The fires were initially modelled based on ‘worst case’ conditions – hot weather, low humidity and high fuel loads with no fuel reduction activities carried out – to establish a profile of ‘maximum risk’. As a comparison exercise, DEPI re-modelled the spread and intensity of the exact same bushfires, under the same weather conditions, but factored in fuel reduction either through planned burning or bushfire. Again, the average impact of these fires on human life and property was recorded and any difference against the maximum risk scenario was noted. By running this comparative modelling for different years, a series of ‘risk profiles’ has been produced for Victoria. The risk profiles depict the residual risk, which is the bushfire risk that remains after fuel reduction. The Victorian Bushfire Risk Profiles Report is an innovative integration of emerging bushfire research with planning, policy, and operational bushfire management, providing an evidentiary base to help inform decision making.