A universal rate of spread index for Australian fuel types

Abstract

Empirical fire spread models for Australian fuel types date back to the 1950s-60s, with the work of Alan McArthur, and extend through to the current day with the most recent developments in shrubland fire spread models and refinements to the curing function in grassland fire spread models. These models are designed to provide a relatively simple and timely answer to the question: “Given a specific set of environmental conditions, what is the expected forward rate of spread of a fire?” In this paper we present a critical analysis of the the current suite of fire spread models employed operationally in Australia. In particular, we explore the functional form and parametric dependence of these rate of spread models. We then introduce an alternative functional form for predicting rate of spread, which is remarkable parsimonious compared to current operational models. We further show that this single functional model can be used as a universal index for fire spread, by which we mean that the same model can be applied to different fuel types and produce numerical predictions that are practically identical to those produced by the existing suite of operational models used in Australia.