Field-based generic empirical flame length–fireline intensity relationships for wildland surface fires

Carlos G. Rossa; David A. Davim; Ângelo Sil; Paulo M. Fernandes

doi:10.1071/WF23127

RESEARCH ARTICLE (Open Access)

Next Contents Vol 33(1)

Field-based generic empirical flame length–fireline intensity relationships for wildland surface fires

Carlos G. Rossa

^A ^B ^* , David A. Davim

^B , Ângelo Sil

^B and Paulo M. Fernandes

^B

+ Author Affiliations

- Author Affiliations

^A School of Technology and Management (ESTG), Polytechnic of Leiria, Apartado 4163, 2411-901 Leiria, Portugal.

^B Centre for Research and Technology of Agro-Environmental and Biological Sciences, CITAB, Inov4Agro, University of Trás-os-Montes and Alto Douro, UTAD, Quinta de Prados, 5000-801 Vila Real, Portugal.

^* Correspondence to: carlos.rossa@ipleiria.pt

International Journal of Wildland Fire 33, WF23127 https://doi.org/10.1071/WF23127

Submitted: 1 August 2023 Accepted: 14 December 2023 Published: 15 January 2024

© 2024 The Author(s) (or their employer(s)). Published by CSIRO Publishing on behalf of IAWF. This is an open access article distributed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License (CC BY-NC-ND)

Abstract

Background

Fireline intensity (I_f) quantifies the power of the fireline and is used for various purposes. I_f and flame length (L_f) are relatable to each other using an empirical power function, which has been considered fuel-specific.

Aims

The aim of this study was to develop generic L_f − I_f relationships based on a robust set of field head fires from the literature (n = 797) conducted worldwide in forest, shrubland and grassland.

Methods

L_f was determined from the base of the fuel bed for comparability across fires in different fuel heights, and the effect of vegetation type was examined.

Key results

Although I_f could be approximately described using the same function in forest and shrubland, fires in grassland required different fitted coefficients; we speculate that fuel particles’ surface area-to-mass ratio is the main fuel metric influencing flame structure.

Conclusions

Fuel-generic relationships for I_f are reasonably accurate and encompass the high end of surface fire I_f. Previous studies suggested their unviability, most likely because of limitations in the number of observations and data ranges, difficulty in objectively measuring L_f and variation in L_f definition.

Implications

The generic relationships presented in this work will be of interest for research and management purposes when specific models for I_f are non-existent.

Keywords: combustion metrics, fire behaviour, fire management, forest, fuel metrics, grassland, head fires, shrubland, surface area-to-mass ratio.

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