Experimental Procedures Characterising Firebrand Generation in Wildland Fires

Abstract

This study aims to develop a series of robust and efficient methodologies, which can be applied to understand and estimate firebrand generation and to evaluate firebrand showers close to a fire front. A field scale high intensity prescribed fire was conducted in the New Jersey Pine Barrens in March 2013. Vegetation was characterised with field and remotely sensed data, fire spread and intensity was characterised and meteorological conditions were monitored before and during the burn. Firebrands were collected from different locations in the forest and analysed for mass and size distribution. The majority were found to be bark slices (more than 70%) with substantial amounts of pine and shrub twigs. Shrub layer consumption was evaluated to supplement the firebrand generation study. Bark consumption was studied by measuring the circumference variation at several heights on each of three different pine trees. The variation was in the same order of magnitude as the bark thickness (1-5 mm). Testing and improving the protocol can facilitate the collection of compatible data in a wide range of ecosystems and fire environments, aiding in the development of solutions to prevent structural ignition at the Wildland Urban Interface.

Investigation of firebrand generation from an experimental fire: Development of a reliable data collection methodology

“…The methodology used in this study is in alignment with a framework developed and presented in El Houssami et al [14] and Filkov et al [15], which reported integrated numbers of firebrands for local fire conditions and their characteristics (size, mass and origin). The novelty of this study includes the quantification of firebrand flux in time with respect to the local fire behavior, wind speed, fuel consumption, fire intensity, and characterizes the exposure of each sampling location.…”

“…Since the methodology is developed with a full set of instruments to accurately measure the firebrands landing ahead of a fire front, it needs to first be tested in relatively controlled conditions at field scale, beginning with low wind speeds. Such a condition is not inherently a drawback for firebrand generation, because it was previously demonstrated that fire-induced drafts at low wind speeds were strong enough to detach bark pieces from tree boles and produce substantial amounts of firebrands [14]. Quantification of firebrand exposure in this way will allow a more complete description of the problem and allow the firebrand fluxes and characteristics to be linked to the fuels and fire behavior.…”

Turbulence and fire-spotting effects into wild-land fire simulators

“…The jump length of the firebrands varies according to the meteorological conditions, the intensity of the fire and the fuel characteristics [57,58,59]. A precise formulation of the landing distributions is difficult due to the limited small scale experimental results [60] and the complexities involved in characterising the detailed aspect of firebrand generation and landing. The firebrands land only in the positive direction and their landing distribution increases with distance to reach a maximum before dropping to zero [61,62].…”

Physical parametrisation of fire-spotting for operational fire spread models: response analysis with a model based on the Level Set Method

“…Researchers have tried to understand the phenomenology of fire-spotting through both experimental and theoretical aspects to update the existing wildfire management decision support systems. Most of the experimental procedures for studying the fire-spotting phenomenon focus on characterization of the gen-5 eration of firebrands (Manzello et al, 2007;El Houssami et al, 2016;Thomas et al, 2017), shape and size of the firebrands (Manzello et al, 2009;Tohidi et al, 2015), drag forces and ignition processes (Manzello et al, 2008). The short temporal and spatial scales of the experiments limit a detailed description of the landing distributions and the flight paths of the firebrands.…”