How can be effect ignition line length on rate of surface fire spread. Fire spread effected by mainly wind speed, fine fuel mositure content and some fuel characteristic.
When fire spreads on level ground in the absence of wind the fire line is always approximately straight and ignition length (IL) does not significantly influence the rate of spread (ROS). On the other hand, when fire is wind or slope-driven the fire line tend to develop a triangular shape, because there is heat transport along the flanks to the head fire (e.g., see Viegas and Rossa 2009, doi:10.1080/00102200903228891). For this reason, the larger the IL, the greater is the amount of heat being transported along the fire line and the larger the ROS. However, above a given IL this effect becomes less pronounced. Anderson et al. (2015, doi: 10.1071/WF14130) indicate that ROS will stabilize for IL above 50 m (for fire spread in shrublands).
Please note that assuming that the effect of the ignition length (IL) on the rate of spread (ROS) will become less significant above given IL values (e.g. 50 m) is a simplification of the problem. A more profound analysis of this effect would require accounting for (at least): i) wind speed and slope angle; ii) length and angle of the fire line flanks; and iii) changes in the radiative heat transfer from the head fire flame to the fuel bed, while the fire changes from a straight line to a triangular shape. I assume that it is because of the complex interactions between these three factors that the IL effect on the ROS becomes less pronounced above a given IL, as suggested by field evidence (e.g. Anderson et al. 2015, doi: 10.1071/WF14130).
Omer, see also these references:
http://www.publish.csiro.au/WF/WF9950237
http://www.publish.csiro.au/WF/WF9970001
https://www.researchgate.net/profile/James_Gould2/publication/228664328_Existing_fire_behaviour_models_under-predict_the_rate_of_spread_of_summer_fires_in_open_jarrah_Eucalyptus_marginata_forest/links/0deec52b35797e1825000000.pdf
http://www.fire.uni-freiburg.de/summit-2003/3-IWFC/Papers/3-IWFC-056-Gould.pdf
http://www.publish.csiro.au/WF/WF00021
http://www.sisef.it/iforest/contents/?id=ifor0992-007
Article Existing fire behaviour models under-predict the rate of spr...
Omer, see also:
Wotton, B.M., McAlpine, R.S., Hobbs, M.W.1999. The effect of fire width on fire behaviour. International Journal of Wildland Fire, 9(4): 247-253.
https://www.fs.fed.us/rm/pubs_other/rmrs_2014_canfield_j001.pdf
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