Quantifying merging fire behaviour phenomena using unmanned aerial vehicle technology

Abstract

Catastrophic wildfires are often a result of dynamic fire behaviours. They can cause rapid escalation of fire behaviour, increasing the danger to ground-based emergency personnel. To date, few studies have characterised merging fire behaviours outside the laboratory. The aim of this study was to develop a simple, fast and accurate method to track fire front propagation using emerging technologies to quantify merging fire behaviour at the field scale. Medium-scale field experiments were conducted during April 2019 on harvested wheat fields in western Victoria, Australia. An unmanned aerial vehicle was used to capture high-definition video imagery of fire propagation. Twenty-one junction and five inward parallel fire fronts were identified during the experiments. The rate of spread (ROS) of junction fire fronts was found to be at least 60% higher than head fire fronts. Thirty-eight per cent of junction fire fronts had increased ROS at the final stage of the merging process. Furthermore, the angle between two junction fire fronts did not change significantly in time for initial angles of 4–14°. All these results contrast with previous published work. Further investigation is required to explain the results as the relationship between fuel load, wind speed and scale is not known.

Analysis of thermal behaviour of merging fire fronts in crop field experiments

“…The use of a drone with a dual visual and thermal camera showed that the thermal camera was able to detect all active hot spots and fire fronts even through dense smoke, which was a significant constraint in our previous study (Filkov et al 2021).…”

“…Most of experimental studies of merging fires have been conducted in the laboratory (Viegas et al 2013;Oliveira et al 2014;Sullivan et al 2019), and only a few in the field (Raposo et al 2018). Filkov et al (2021) have demonstrated that the fire behaviour associated with merging fires in the field can be different and there remain 'scale-gaps' in the experimental data used to inform model development. Moreover, information about Advances in Forest Fire Research 2022 -D. X.…”

Slope effect on junction fire with two non-symmetric fire fronts

“…This problem was studied by Viegas et al (2012), who initially described this phenomenon as a 'jump fire', and developed a conceptual analytical model for the rate of advance of the intersection point or vertex of two oblique and symmetric fire fronts. Several research works on experimental, analytical and numerical simulation of this problem followed (Sharples et al 2013;Viegas et al 2013;Raposo et al 2015Raposo et al , 2018Hilton et al 2016;Thomas et al 2017;Sullivan et al 2019;Filkov et al 2021). The fire fronts were always symmetrical in relation to the vertex V and there was no fuel bed to burn outside the linear straight fire lines.…”

Physics-based modelling of junction fires: parametric study

“…Previous attempts to examine the behaviour of junction fire were mostly experimental, at the laboratory scale (Viegas et al 2012(Viegas et al , 2013Raposo et al 2018;Sullivan et al 2019) with some work at the field scale (Raposo et al 2018;Filkov et al 2021). Viegas et al (2012) conducted a set of non-slope junction fire experiments.…”

“…However, there was no enhanced ROS over what was expected from geometric considerations. Filkov et al (2021) conducted field-scale experiments and developed a method to track fire front propagation using emerging drone technologies for various fire scenarios including merging fire. They found almost constant propagation with an acceleration in the last phase for some cases, in contrast to Viegas et al (2012Viegas et al ( , 2013 and Raposo et al (2018).…”