Australian Fire Danger Rating System: implementing fire behaviour calculations to forecast fire danger in a research prototype†

Abstract

Background The Australian Fire Danger Rating System (AFDRS) was implemented operationally throughout Australia in September 2022, providing calculation of fire danger forecasts based on peer-reviewed fire behaviour models. The system is modular and allows for ongoing incorporation of new scientific research and improved datasets. Aims Prior to operational implementation of the AFDRS, a Research Prototype (AFDRSRP), described here, was built to test the input data and systems and evaluate the performance and potential outputs. Methods Fire spread models were selected and aligned with fuel types in a process that captured bioregional variation in fuel characteristics. National spatial datasets were created to identify fuel types and fire history in alignment with existing spatial weather forecast layers. Key results The AFDRSRP demonstrated improvements over the McArthur Forest and Grass Fire Danger systems due to its use of improved fire behaviour models, as well as more accurately reflecting the variation in fuels. Conclusions The system design was robust and allowed for the incorporation of updates to the models and datasets prior to implementation of the AFDRS.

Live trial performance of the Australian Fire Danger Rating System – Research Prototype†

“…Eight operationally available fire spread models were selected as the core for the AFDRS RP , as described in detail by Kenny et al (2024). For convenience, they are listed here: (1) Forest; (2) Grassland; (3) Northern Grassland (Savanna); (4) Spinifex; (5) Mallee-Heath; (6) Shrubland; (7) Buttongrass; and (8) Pine.…”

“…Calculations were computed daily by the Bureau of Meteorology using gridded forecast weather at hourly intervals at a 1.5-km resolution across Australia. Each grid cell was assigned to one of the eight broad fuel types (Kenny et al 2024) and with the weather forecast and fuel characteristics combined, fire behaviour metrics such as rate of spread, intensity, flame height and spotting distance were calculated by using the corresponding fire behaviour model. These metrics were subsequently classified into the rating categories as defined by Hollis et al (2024a).…”

“…Given that only 7% of Australia's vegetation can be classified as forest and 61% as grass (Kenny et al 2024), this means that 32% of the Australian vegetation was potentially misrepresented in the FFDI/GFDI system. Further, in the McArthur system, the FFDI and GFDI do not allow for the wide variation in vegetation across the Australian continent.…”

“…For example, spinifex hummock grass (Triodia spp. ), woodlands and agricultural land (pasture, crops) are all treated as grassland, even though fire behaviour in these fuel types is very different to that in continuous grasslands (Kenny et al 2024;Cheney et al 1998;Burrows et al 2018). While fire behaviour models for fuel types other than forest and grassland have been developed over the past ~25 years (Cruz et al 2015a), these had not been used to define fire danger ratings in Australia prior to 2022.…”

“…This would benefit a wide range of land managers and fire practitioners, and overall should lead to improved public warning messages (Cube Group 2015). After some previous groundwork, a AFDRS RP was built between April and October 2017 (Kenny et al 2024). The purpose of the AFDRS RP was to demonstrate that it is feasible to develop a fire danger rating system that is national, modular and open to continual improvement.…”