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Developing an Impact Index for the Australian Fire Danger Rating System: predicting potential structure loss from wildfires

Dan Krix , James Monks, Alex Holmes, Meaghan Jenkins, Stuart Matthews, Samuel Sauvage, John Runcie

Abstract

Abstract Background. Accurately predicting impacts of wildfires remains a top priority for fire and land management agencies. The Australian Fire Danger Rating System (AFDRS) redesigned forecasts of fire danger for Australian fire agencies, modernising the fire danger system. The next phase of the AFDRS focuses on developing indices for Fire Ignition, Suppression, and Impact (FISI). Aims. Impact models were developed to predict structure loss at the bushland-urban interface in Eastern Australia. Methods. Structure counts, cleared land, and canopy height, calculated at radii 50 to 1000 m from structures, and terrain ruggedness were used to model individual structure loss during wildfire, and proportional loss in built-up areas. Key results. The individual and proportional structure loss models accurately predicted structure loss (individual losses: TPR = 0.67, TNR = 0.69; proportional loss r2 = 0.71 ). Loss was lowest where structures had defensible space on flat ground, with higher numbers of structures nearby and shorter vegetation canopy height. Conclusions. The models determine the probability of structure loss during destructive wildfire. Implications. These models provide fire agencies information on the likelihood of structure loss and aid in decision-making. The Impact Index may support effective resource allocation, potentially reducing structure loss.

WF24148  Accepted 21 July 2025

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