Methodology to obtain isochrones from large wildfires

Abstract

In Mediterranean countries, a change in traditional uses of land has caused an increase in both the number of fires and the land area affected by fires. This situation creates a need to improve the efficiency and effectiveness of wildfire extinguishing devices. This improvement should be based on knowledge of the fire behaviour of various fires affecting similar areas. To study these fires, we considered a methodology to obtain isochrones at different stages of a wildfire through temporal georeferencing of aerial fire photographs. This methodology was applied to two large wildfires (1098 and 4609ha) that occurred in 2009 in the south of Spain. A total of 463 and 611 photographs were considered to respectively obtain seven and nine isochrones. These isochrones are representative of the development of the fires. In periods of greater intensity, this study exhibits a rate of propagation much higher than expected, reaching 7.8hamin–1 of burned surface and 160.0mmin–1 of perimeter growth in one example, whereas if we considered only the final perimeter of the fire, the speed of burned perimeter generation would be 28.2mmin–1 and of burned surface, 2.4hamin–1.