Wind and slope effects on ROS during the fire propagation in East-Mediterranean pine forest litter

Abstract

The paper presents data from laboratory experimental burns modelling the effects of slope of ground surface and wind velocity over the fire spread in the pine litter layer. Subjected to the study are samples from Pinus halepensis and Pinus pinaster pine needles collected in a specific region in Greece. Statistical processing of results obtained has also been carried out and equations have been drawn up presenting the relationship between the rate of spread and changes in wind velocity and slope of terrain. Statistical models for rate of fire spread (ROS) are based on the individual effects of the two factors over the increase in the rate of fire spread above its baseline value. The spread rates in P. halepensis were higher than in P. pinaster beds and the combustion process took place mainly on the fuel top surface. The most severe case of fire propagation has been monitored when the leading edge of the fire front was moving upslope and in matching direction with the wind. The rate of spread for a fire front moving upslope with back-wind direction has been influenced mainly by the slope; however, the negative value of the wind flow reduced the spread rate. The results obtained and equations produced provide a basis to carry out a risk analysis for fire spread in the studied vegetation species taking into account specific terrain features and climate characteristics in the specified geographic area.