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.