Assessing wildland fire suppression effectiveness with infrared imaging on experimental fires

Background: Suppression effectiveness is often evaluated by measuring the extent to which it slows fire spread and reduces fireline intensity. Although studies have used infrared (IR) imaging methods to explore suppression effectiveness, most do not measure or assess the influence of water application on energy release.

Aims: This preliminary analysis uses IR imagery to quantify the impact of suppression on fire behaviour and the reduction in energy released from a flaming fire.

Methods: We conducted a series of small-scale experimental burns representative of pine and grass surface litter in the Canadian boreal forest and suppressed these fires while actively monitoring fire behaviour with overhead IR imagery. We used detailed measurements of fire radiative power to estimate fire radiative energy density, forward rate of spread and fireline intensity.

Key results: We observed changes in fire behaviour due to suppression, quantified the duration of those reductions and detected a suppression signal through an analysis of radiative energy during the flaming combustion phase.

Conclusions: IR methodology is able to capture the changes in energy released from a fire due to known aspects of water application.

Implications: Our findings can inform methodologies for field studies on suppression effectiveness, where ground sampling techniques are impractical but airborne IR methods can be employed.