Explore UCD

UCD Home >

Smouldering Fire in Peatlands

On this page

Smouldering Fire in Peatlands

People: (opens in a new window)Nuria Prat, (opens in a new window)Claire Belcher, (opens in a new window)Rory Hadden, (opens in a new window)Guillermo Rein, (opens in a new window)Jon Yearsley

Smouldering Fire in Peatlands 3

Our research focuses on a form of combustion called(opens in a new window)smoulderingand its propagation through organic soils, such as peat. Smouldering is very different from flaming combustion (Table 1).
 
Our research aims to improve our understanding of smouldering fire phenomena in natural peatlands, and eventually inform the policy and management of smouldering peatland fires.

Table 1: Some differences between smouldering and flaming combustion
  Impact Flame Temperature (degrees C) Propagation Spread Rate (cm/hour)
Flaming vegetation yes 1500 fast 100
Smouldering soil no 500-700 slow <5

Laboratory Experiments

IR image of smouldering peatWe runsmall-scale laboratory experiments. In these experiments we mimic the heterogeneous moisture distribution found in real peatlands and record the propagation of the smouldering fire using infra-rad cameras (pictured right), visual images, thermocouples and changes in mass.

burn box filled with peatdivider

PDF posters describing the research

Publications

  1. Stracher GB, Prat-Guitart N, Nugent C, Mullen E, Mitchell FJG, Hawthorne D, Belcher CM, Yearsley JM. 2019.Peat fires in Ireland. Chapter 20, Coal and Peat Fires: A Global Perspective, Ed G.B. Stracher, Vol 5, p451-482.(opens in a new window)DOI: 10.1016/B978-0-12-849885-9.00020-2
    5
    5 total citations on Dimensions.
  2. Prat-Guitart, N., Belcher, C.B., Thompson, DK, Burns, P., Yearsley, J.M., 2017.'Fine-scale distribution of moisture in the surface of a degraded blanket bog and its effects on the potential spread of smouldering fire. Ecohydrology. [(opens in a new window)Weblinkmodule info]
    (opens in a new window)Article has an altmetric score of 13
    8
    8 total citations on Dimensions.
  3. Prat-Guitart, N., Rein, G., Hadden, R.M., Belcher, C.M., Yearsley, J.M., 2016.Effect of spatial heterogeneity in moisture content on the horizontal spread of peat fires. Science of the Total Environment, Vol. 572, p1422-1430. [(opens in a new window)Weblinkmodule info]>
    (opens in a new window)Article has an altmetric score of 7
    39
    39 total citations on Dimensions.
  4. Prat-Guitart, N., Rein, G., Hadden, R.M., Belcher, C.M., Yearsley, J.M., 2016.Propagation probability and spread rates of self-sustained smouldering fires under controlled moisture content and bulk density conditions.International Journal of Wildland Fire, Vol 25, p456-465. [(opens in a new window)Weblink]
    (opens in a new window)Article has an altmetric score of 9
    59
    59 total citations on Dimensions.
  5. Prat-Guitart, N., Hadden, R.M., Belcher, C.M., Rein, G., Yearsley, J.M., 2015.Infrared image analysis as a tool for studying the horizontal smoldering propagation of laboratory peat fires, in: Stracher, G.B., Prakash, A., Rein, G. (Eds.), Coal and Peat Fires, A Global Perspective. Peat - Geology, Combustion and Case Studies. Elsevier, Amsterdam, pp. 121–139. [(opens in a new window)Weblinkmodule info]
  6. Prat N., Belcher B.,Hadden R., Rein G., Yearsley J. (2015)A laboratory study of the effect of moisture content on the spread of smouldering in peat fires, FLAMMA, Vol. 6, Issue 1, p35-38 [(opens in a new window)Weblinkmodule info]
  7. Hudspith, V. a, Belcher, C.M., Yearsley, J.M., 2014.Charring temperatures are driven by the fuel types burned in a peatland wildfire. Frontiers in Plant Science. (5), 714. [(opens in a new window)Weblinkmodule info]
    (opens in a new window)Article has an altmetric score of 2
    29
    29 total citations on Dimensions.
  8. Prat, N., Hadden, R., Rein, G., Belcher, C., Yearsley, J., 2013.Effect of peat moisture content on smouldering fire propagation, in: Wade, D., Fox, R. (Eds.), Proceedings of 4th Fire Behavior and Fuels Conference. International Association of Widland Fire, Missoula, USA, pp. 248–250. [(opens in a new window)Weblinkmodule info]
  9. Yearsley, J., Belcher, C.M., Hadden, R.M., Prat, N., Rein, G., 2013.Linking smouldering experiments with simple cellular automata models of smouldering fires, in: Wade, D., Fox, R. (Eds.), Proceedings of the 4th Fire Behaviour Conference. International Association of Wildland Fire, Missoula, USA, pp. 156–158. [(opens in a new window)Weblinkmodule info]
  10. Belcher, C.M., Yearsley, J.M.., Hadden, R.M., McElwain, J.C., Rein, G., 2010.Baseline intrinsic flammability of Earth’s ecosystems estimated from paleoatmospheric oxygen over the past 350 million years.Proceedings of National Academy of Science (107), 22448–22453. [(opens in a new window)Weblinkmodule info]
    (opens in a new window)Article has an altmetric score of 31
    157
    157 total citations on Dimensions.

Partners

Funding:

What is Smouldering?

Smouldering is a slow, flame-less form of combustion that can persist for long periods of time. It can spread over extensive areas, spreading through sub-surface layers of soil with high organic matter (e.g. peat, humus, duff).

exposed tree roots after a smouldering fireWhen peat is dry smouldering can be initiated by weak sources of heat (e.g. flaming vegetation). Once ignited smouldering fires are difficult to extinguish and can abruptly start flaming fires.

    The main visible consequences of a smouldering fire are:
  • smoke haze,
  • removal of soil layers,
  • ground destabilisation
  • local subsidence

Several of these cause habitat loss, damage to root systems (pictured right) and produce important carbon emissions. Peat fires can affect especially drained peatlands and forests or plantations with a shallow layer of peat.

Table 1: Some differences between smouldering and flaming combustion
  Impact Flame Temperature (degrees C) Propagation Spread Rate (cm/hour)
Flaming vegetation yes 1500 fast 100
Smouldering soil no 500-700 slow <5

References

Smouldering Fires and Natural Fuels, by G Rein, Chapter 2 in: (opens in a new window)Fire Phenomena in the Earth System - An Interdisciplinary Approach to Fire Science, C Belcher (editor). Wiley and Sons, 2013.

Laboratory controlled burns of smouldering peat

combustion lab set-up

Below are a couple of videos of our laboratory controlled burns. These videos last for ~1min, but in reality these smouldering burns take several hours. The burns are for peats with ~0% and 100% moisture content (measured as a percentage of dry weight).

The experimental setup is shown on the right. The burn box is 20cm x 20cm and 10cm deep. Combustion is started (top of the videos) by passing a controlled electrical current through a coil of heating wire (100W for 30 mins).

The smouldering propagation is recorded with: a webcam, an infrared camera, thermocouples inside the peat and an electronic balance. These data are then analysed in Matlab and R to extract the velocity of the smouldering combustion front, the mass loss rate of the sample and the temperature at the smouldering combustion front. These data can be used to parameterise models of smouldering combustion.

divider

Time-lapse video of a Dry-Peat Burn

Peat smouldering experiment (peat at ~0% moisture content). Left hand image is visual movie showing pyrolysis front, right hand image is an infrared movie showing the exothermic region (oxidation). The colour scale on the infrared image is room temp (dark blue) to ~400 degrees C (red).

Time-lapse video of a Wet-Peat Burn

Peat smouldering experiment (peat at 100% moisture content). Left hand image is visual movie showing pyrolysis front, right hand image is an infrared movie showing the exothermic region (oxidation). The colour scale on the infrared image is room temp (dark blue) to ~400 degrees C (red).

Time-lapse video of a typical burn experiment

Example of a peat burning experiment showing the radial spread of the fire from a central ignition point. The left-hand video is a visual webcam video of the smouldering peat. Right-hand is an infrared video of the same peat burn. A 10 cm long glowing coil ignites the peat from the centre of the peat sample. The self-sustained spread is produced in a radial fashion until the box walls. Experiments like that are used to test the influence of laboratory conditions, such as air flow, to the smouldering fire spread in fine-scale burning experiments.

Time-lapse video of a typical burn experiment

Example of data collected during a peat burning experiment. Top left image is a webcam recording of the smouldering peat. Top right image is an infrared image of the same burn, bottom is a graph of the radiative power detected from one pixel of the infrared image (pixel marked with a white dot). The peat is ignited along one site of the box using a glowing coil covered by dry peat. The smouldering fire self-spreads horizontally through the peat sample. Each pixel in the infrared image is a power density value (kW/m^2) and is used to locate the smouldering front inside the box. The graph below shows the power density of the pixel highlighted in white in the visual and infrared images. There is no change in the power intensity until the smouldering front gets very close to the pixel causing the power density to increase rapidly due to the start of exothermal oxidation reactions. The values are high for the duration of the peat and char oxidation and then they have a slower cool down phase. Each pixel has similar graphs that can be used, for example, to estimate the spread rates of the fire.

Have you seen a smouldering peatland?

exposed tree roots after a smouldering fire

      Have you
    • recently seen a smouldering fire on a peatland in Ireland?
    • information about past smouldering fires on peatlands?
      • If you have then we would like to hear from you because your information could help us with our research.

Please contactNuria Prat((opens in a new window)nuria.prat-guitart@ucdconnect.ie)

info

Download a PDF information sheet about smouldering peat fires here

divider

    Keys to identify smouldering fire:
  1. Smoke coming from the ground
  2. Slow propagation
  3. Holes in the ground and soil collapse
  4. Burnt surface patches
  5. Tree destabilisation

Ecological Modelling

University College Dublin, Belfield, Dublin 4, Ireland.
T: +353 1 716 7777 |