Effects of spatial heterogeneity in moisture content on the horizontal spread of peat fires
File(s)
Published version
Author(s)
Prat-Guitart, N
Rein, G
Hadden, RM
Belcher, CM
Yearsley, JM
Type
Journal Article
Abstract
The gravimetric moisture content of peat is the main factor limiting the ignition and spread propagation of smouldering fires. Our aim is to use controlled laboratory experiments to better understand how the spread of smouldering fires is influenced in natural landscape conditions where the moisture content of the top peat layer is not homogeneous. In this paper, we study for the first time the spread of peat fires across a spatial matrix of two moisture contents (dry/wet) in the laboratory. The experiments were undertaken using an open-top insulated box (22. ×. 18. ×. 6. cm) filled with milled peat. The peat was ignited at one side of the box initiating smouldering and horizontal spread. Measurements of the peak temperature inside the peat, fire duration and longwave thermal radiation from the burning samples revealed important local changes of the smouldering behaviour in response to sharp gradients in moisture content. Both, peak temperatures and radiation in wetter peat (after the moisture gradient) were sensitive to the drier moisture condition (preceding the moisture gradient).Drier peat conditions before the moisture gradient led to higher temperatures and higher radiation flux from the fire during the first 6. cm of horizontal spread into a wet peat patch. The total spread distance into a wet peat patch was affected by the moisture content gradient. We predicted that in most peat moisture gradients of relevance to natural ecosystems the fire self-extinguishes within the first 10. cm of horizontal spread into a wet peat patch. Spread distances of more than 10. cm are limited to wet peat patches below 160% moisture content (mass of water per mass of dry peat). We found that spatial gradients of moisture content have important local effects on the horizontal spread and should be considered in field and modelling studies.
Date Issued
2016-04-20
Date Acceptance
2016-02-20
Citation
Science of the Total Environment, 2016, 572, pp.1422-1430
ISSN
0048-9697
Publisher
Elsevier
Start Page
1422
End Page
1430
Journal / Book Title
Science of the Total Environment
Volume
572
Copyright Statement
© 2016 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).
Subjects
Science & Technology
Life Sciences & Biomedicine
Environmental Sciences
Environmental Sciences & Ecology
Peatland
Smouldering
Propagation
Breakpoint analysis
Step-change
Infrared image analysis
BLACK SPRUCE FORESTS
SMOLDERING COMBUSTION
NORTHERN PEATLAND
CARBON STOCKS
ORGANIC SOILS
BULK-DENSITY
CONSUMPTION
SPHAGNUM
WILDFIRE
DUFF
MD Multidisciplinary
Publication Status
Published