A rate of spread index for fires in spinifex fuels

Abstract

Fires in spinifex occur throughout arid and semi-arid parts of Australia and in some cases can affect large tracts of the landscape with associated environmental impacts. In response to this environmental challenge an empirical model for the prediction of fire spread rate in spinifex fuels has recently been developed, based on a number of experimental burns conducted in Western Australia. In other research related to fires in grasslands, a simple rate of spread index for quasi-equilibrium fire spread was developed and, despite its simplicity, was shown to provide practically identical output to current operational grassland fire spread prediction models. This simple rate of spread index for grasslands conceptualises the rate of fire spread as wind speed divided by fuel moisture content, where fuel moisture content is estimated using a fuel moisture index (FMI). Such a conceptualisation embodies the notion that fires will spread faster in windier conditions and in fuels that are drier. The rate of spread index, as it applied to grassfires, also incorporates a term that accounts for an intensity-dependent indraft that counters the prevailing winds at the fire line. As such, the rate of spread index can be viewed as a two parameter model for quasi-equilibrium fire spread