Coupled influences of topography and wind on wildland fire behaviour

Abstract

Ten simulations were performed with the HIGRAD/FIRETEC wildfire behaviour model in order to explore its utility in studying wildfire behaviour in inhomogeneous topography. The goal of these simulations is to explore the potential extent of the coupling between the fire, atmosphere, and topography. The ten simulations described in this paper include five different topographies, each run with two different ambient wind speeds of 6 and 12 m s–1. The five topologies explored are: an idealised hill (which serves as the base centerline for the other topographies), two variations of the hill with lateral gradients downwind from the ignition line (one sloping up from the ‘hill’ at the centerline to form an upward sloping canyon parallel to the ambient wind, and the other sloping down from the centerline to form a ridge parallel to the ambient flow), one with a second hill upwind of the ignition line such that the fire is ignited in the bottom of a canyon that runs perpendicular to the ambient wind, and finally a flat terrain. The four non-trivial topographies have the same profile along the centerline downwind of the ignition line to help assess the impacts of topographic gradients that are perpendicular to the ambient wind. It is hoped that analysis of these simulations will help reveal where point-functional models are sufficient, where topographically modified wind fields are needed, and where fully coupled fire and transport models are necessary to properly describe wildfire behaviour.

Detecting regional differences in within-wildfire burn patterns in western boreal Canada

“…Strong local winds in the Foothills and Rocky Mountain areas (Burrows 1903) are likely to cause more spot fire activity (Albini 1979) than in the Boreal Forest or Boreal Shield. Fire behaviour also becomes increasingly influenced by the greater topographic complexity in the Foothills and Rocky Mountain areas (Linn et al 2007). Foothills and Rocky Mountain landscapes also tend to be dominated by continuous pure conifer stands, which are fuel types associated with higher probabilities of burning.…”

Identifying geographical patterns of wildfire orientation: A watershed-based analysis

“…Of course, much more remains to be done concerning the complex, finer-scale interactions between wind and topography and their effects on fire behavior (Linn et al, 2007;Sharples, 2008). Further clarification of regional fire spread directions will be gathered from analysis of smoke plumes and time series of active fire, observed with satellite imagery.…”

The Spotting Distribution of Wildfires

“…The atmospheric boundary layer (ABM) is the lowest portion of the atmosphere, extending on average about one kilometre, and ranging up to at most about three kilometres above the Earth's surface [72]. It consists of a number of distinct sublayers, and it is of utmost importance since the ABM is where firebrand transport occurs.…”