Managing road corridors to limit fire hazard. A simulation approach in southern France

Abstract

Road corridors are sources of fire ignition and fire spread in French Mediterranean areas, but little is known about the flammability of vegetation and the probability of fire ignition and spread to neighbouring forests. This study simulated fire propagation in road corridors with the help of a cellular automata (CA). We assessed the relative importance of vegetation type, fuel treatment and the spatial patterning of vegetation on the probability of fire spreading to forests. The cellular automaton simulator was implemented with different types of corridors (30 m × 40 m), on the basis of an extensive field survey of vegetation. We used data from laboratory flammability experiments to determine the probability of ignition and propagation for each of the 20 cm × 20 cm cells of the CA. The probability of a fire reaching the neighbouring forest ( P FR ) indicated that certain types of road corridors represent a very high risk owing to a combination of highly flammable vegetation and high spatial connectivity. The lowest P FR values correspond to corridors with a decreasing vegetation flammability gradient in the vicinity of the forest. A several meter-wide embankment with low-flammable and/or managed vegetation can substantially reduce P FR . These results suggest that firewise landscaping and local vegetation management can reduce fire risk in road corridors. Each corridor type should be subjected to specific vegetation management to account for flammability, growth pattern and lifetime.