|Title||What are the safety implications of dynamic fire behaviours?|
|Publication Type||Conference Paper|
|Year of Publication||2017|
|Authors||Lahave, S, Sharples, JJ, Matthews, S, Heemstra, S, Price, OF|
|Conference Name||22nd International Congress on Modelling and Simulation|
Many firefighters in the world have been injured or killed due to a forest fire entrapment, caught by the fire heat or smoke. Some case studies have pointed out that dynamic fire behaviour may have played a role. We investigate here how changes in wind direction, channelling (i.e. vorticity-driven lateral spread on a leeward slope) and long distance spotting could contribute to entrapments through a process model, simplified in Figure 1. There are three situations likely to entrap firefighters:
We review fire agencies archives in Australasia and Europe from 1979 to 2017 and retrieve 106 entrapments, investigating weather, terrain and location of fire front during entrapment. We also compare the Australasian subset with fires without entrapment using a binomial regression function.
In Australia, changes in wind direction induced by cold front passes is the main factor contributing to entrapment. These sudden changes in wind direction switch long smooth burning flanks of fire in violent fronts and lead to S1 situations. S2, sudden lateral spread, occurs in rough terrain. There, leeward slopes may generate channelling, causing entrapment several hundred meters far away from the fire flank. S3 appears when fire danger index reaches highest values. When fuel drought combines with adverse weather conditions, mass spotting propagates fire at long distance. Then, firefighters may be entrapped whatever the terrain.
This work improves our understanding of the process from dynamic fire behaviour to firefighter entrapment. Identifying three different situations, the model should help fire agencies to adapt their safety warnings regarding the local daily conditions.