Head Fire Instensity
The head fire intensity is defined as the rate of heat energy release per unit time per unit length of a fire front. It accounts for both the fuel consumption and the spread rate of a fire, giving an idea of the difficulty of controlling a fire and thus being of very useful for firefighting.
You may also see this parameter referred to in the literature as frontal fire intensity or line fire intensity.
(Foresty Canada, 1992, p38).