Coupled assessment of fire behaviour and firebrand dynamics

The hazards associated with firebrands have been well documented. However, there exist few studies that allow the hazard from a given fire to be quantified. To develop predictive tools to evaluate this hazard, it is necessary to under-stand the conditions that govern firebrand generation and those that affect firebrand deposition. A method is presented that allows time resolved measurements of fire behaviour to be related to the dynamics of firebrand deposition. Fire-brand dynamics were recorded in three fires undertaken in two different ecosystems. Fire intensity is shown to drive firebrand generation and firebrand deposition – higher global fire intensities resulting in the deposition of more, larger firebrands at a given distance from the fire front. Local firebrand dynamics are also shown to dominate the temporal firebrand deposition with periods of high fire intensity within a fire resulting in firebrand shower at deposition sites at times commensurate with firebrand transport. For the range of conditions studied, firebrand deposition can be expected up to 200 m ahead of the fire line based on extrapolation from the measurements.