Victoria’s bushfire management sector continually works to improve the data and science that inform its decisions. As technology improves, better data becomes available, research programs elicit new knowledge, or mapping accuracy improves, the models improve and metrics, such as fuel-driven bushfire risk or ecosystem metrics, are recalculated.
Each year, updates are made to this report to respond to these improvements - ensuring the best-available models and data inform public reporting.
Readers should compare this report and past and future reports in that context. For the most accurate view of current and historical figures, you should always consult the most recent bushfire risk management report.
Changes to reported bushfire risk
This year’s report includes more accurate results from those reported in 2020–21 as improvements were made to both fire history data and the Phoenix RapidFire bushfire simulation software – leading to re-calculation of bushfires across multiple years.
The influence of these improvements is captured, over time, in Table 20.
Although there were no changes to the statewide fuel-driven bushfire risk levels in 2020–21, there were slight changes in the reported risk at the regional level in four regions, these are presented in Table 21.
Table 20: Changes and improvements to the reported bushfire risk percentage and reasons for the change
|Recalculated risk||59%||63%||66%||68%||70%||63%||No change||n/a|
|Model updates||2016 Phoenix model update||2016 Phoenix model update||2016 Phoenix model update||Updates to Phoenix software and data inputs||No change||No change||No change||No change|
|Fire history layer changesi||2021||2021||2021||2019||2022||2022||No change||No change|
n/a = not applicable.
i Note this indicates the year the relevant data was developed against the year the recalculation was applied.
Table 21: Changes to reported Tolerable Fire Interval
|Region||Barwon South West||Gippsland||Grampians||Hume||Loddon Mallee||Port Phillip|
|Reported 2020–21 fuel-driven bushfire risk||62%||42%||75%||69%||71%||85%|
|Recalculated 2020–21 fuel-driven bushfire risk||No change||43%||74%||67%||No change||84%|
A significant influence on this recalculation were a suite of improvements to the Phoenix RapidFire bushfire simulation software and the bushfire risk calculation process, including:
- improving fuel-type mapping by:
- more accurately mapping the extent of woody vegetation across Victoria
- updating plantation, irrigation area and water-body mapping
- expanding fuel-type mapping into South Australia and New South Wales
- deploying a new version of the Phoenix RapidFire software (version 4007), which improves bushfire spread simulations by better accounting for convection, spotting and ember density
- expanding the Phoenix RapidFire software ignition grid by 40 kilometres into South Australia and New South Wales to complement the expansion of the fuel-type mapping
- improving the accuracy of address point locations, which are used to estimate bushfire risk, across Victoria; these improvements resulted in updated bushfire risk profiles, which show risk to be about 10% lower than estimated using the previous version of the Phoenix software and previous data.
These updates to the Phoenix RapidFire model were used in recalculations to all previously reported bushfire risk figures and showed a decrease in bushfire risk from that previously reported, dating back to 2012–13.
The second significant influence on this recalculation is the continual improvement in mapping accuracy for areas treated by planned burning - impacting foundational fire history data. This data had significant improvements in 2019, 2021 and 2022.
Changes to reported ecosystem resilience
As with reported fuel-driven bushfire risk, the improvements in mapping and accounting of areas treated by planned burning and subsequent re-modelling influence the calculation of ecosystem resilience metrics.
Changes to reported Tolerable Fire Interval (TFI) and Growth Stage Structure (GSS) are shown in Table 22 and Table 23, respectively.
The fire history improvements shown in Table 20 (above), where mapping improvements have picked up additional areas impacted by fire, resulted in the modelling showing an increase in vegetation within the juvenile age class and a reduction in the amount of vegetation without known fire history.
Table 22: Changes to reported tolerable fire interval, Victoria, 2020–21.
|Year||Below Min TFI||Within TFI||Above Max TFI||No Fire History|
Adjusted with fire history improvements
Table 23: Changes to the reported Growth Stage Structure, Victoria, 2020–21.
|Year||Juvenile||Adolescent||Mature||Old growth||No Fire History|
Adjusted with fire history improvements
Changes to FFMVic reported costs
Changes in the split between direct and indirect costs have been applied retrospectively in Table 24 to enable a direct comparison between the financial years shown, based on the accounting method developed in 2018–19 and applied in subsequent years.
FFMVic’s fuel management program investment is split between direct and indirect costs. Specific amendments have been made to better capture the activities related to fuel management and non-fuel management investment, because of improvements made to the accounting method and categorisation of expense types over time. The changes reported in this section for direct and indirect investment for the fuel management program from 2016–17 to 2021–22 are the result of changes made to the categorisation of costs as being direct, indirect and/or non-fuel management expenses.
Direct costs relate to investment that can be directly and reliably assigned to individual fuel management operations (such as materials, plant and aircraft hire, overtime and allowances, overnight accommodation and meals).
Indirect fuel management costs include expenses relating to base salaries, training, vehicles, equipment, planning and community engagement. This year, indirect costs also include investment in native vegetation improvements, which are activities undertaken to offset impacts to biodiversity resulting from FFMVic’s bushfire preparedness activities.
Non-fuel management expenses are typically those relating to preparedness and fire and emergency response activities (such as fire radio network costs, systems and aviation spending). These are not reflected in Table 24.
Table 24: Changes to reported fuel management expenditure in the current and previous reports
|Total fuel management expenditure reported in current year (based on 2018–19 accounting method)||97.9||113.5||121.7||109.2||155.8||151.0|
|Direct fuel management expenditure reported in current year||11.2||14.6||18.2||10.9||42.4||37.3|
|Indirect fuel management expenditure reported in current year||86.7||98.9||103.5||98.2||113.4||113.7|
|Total fuel management expenditure reported in that year||107.9||107.8||121.7||109.2||155.8||151.0|
|Direct fuel management expenditure reported in that year||40.0||30.4||18.2||10.9||42.4||37.3|
|Indirect fuel management expenditure reported in that year||67.9||77.4||103.5||98.2||113.4||113.7|
|Net change in fuel management reported expenditure||–10.0||5.7||0.0||n/a||n/a||n/a|
n/a = not applicable.