An efficient, multi-scale neighbourhood index to quantify wildfire likelihood.

Background: To effectively reduce future wildfire risk, several management strategies must be evaluated under plausible future scenarios, requiring models that provide estimates of how likely wildfires are to spread to community assets (wildfire likelihood) in a computationally efficient manner. Approaches to quantifying wildfire likelihood using fire simulation models cannot practically achieve this because they are too computationally expensive. Aim: This study aimed to develop an approach for quantifying wildfire likelihood that is both computationally efficient and able to consider contagious and directionally specific fire behaviour properties across multiple spatial 'neighbourhood' scales. Methods: A novel, computationally efficient index for quantifying wildfire likelihood is proposed. This index is evaluated against historical and simulated data on a case study in South Australia. Key results: The neighbourhood index explains historical burnt areas and closely replicates patterns in burn probability calculated using landscape fire simulation (ρ = 0.83), while requiring 99.7% less computational time than the simulation-based model. Conclusions: The neighbourhood index represents patterns in wildfire likelihood similar to those represented in burn probability, with a much-reduced computational time. Implications: By using the index alongside existing approaches, managers can better explore problems involving many evaluations of wildfire likelihood, thereby improving planning processes and reducing future wildfire risks. Wildfire likelihood is quantified in a computationally efficient manner using a multi-scale 'neighbourhood index'. This is achieved by aggregating fire behaviour properties across multiple neighbourhood scales. The index is much more computationally efficient than alternative approaches and considers contagious and directionally specific fire behaviour properties across multiple spatial 'neighbourhood' scales. This article belongs to the Collection Fire & Climate. [ABSTRACT FROM AUTHOR]