Exploring the influence of the Keetch-Byram Drought Index and McArthur's Drought Factor on wildfire incidence in Victoria, Australia

Abstract

Background: Wildfires are thought to become more prevalent during periods of extended dry weather. This issue is examined using two dryness metrics commonly applied in Australian fire management agencies. Aims: This paper investigated links between wildfire incidence and the Keetch-Byram Drought Index (KBDI) and McArthur's Drought Factor (DF) across the state of Victoria, Australia. Methods: Weather records and data from 41 418 wildfires that occurred across the State over a 17-year period were compiled to examine the distributions of KBDI and DF on days with fires smaller and larger than 5 ha in area and all days, using kernel density plots. Key results: Days with fires, particularly days with fires that escaped initial attack, have higher DFs and KBDIs compared with all days. These differences vary between regions and are greatest in areas with moist climates. Conclusions and implications: An appreciation of dryness conditions using tools such as KBDI and DF is useful for understanding fire potential, particularly in areas that experience higher and more regular rainfall.