Fire behaviour simulation in Mediterranean maquis using FARSITE (fire area simulator)

In the last two decades several simulation systems were developed to provide information about temporal and spatial variations of fire spread and behaviour. FARSITE (Fire Area Simulator), one of the most common simulators, is a spatially and temporally explicit fire simulation system. The simulator is based on Rothermel's fire spread model, and describes the fire spread and behaviour as a function of relationships among fuels, topography and weather conditions. The use of FARSITE on areas different from those where the simulator was originally developed requires a local calibration in order to produce reliable results. This is particularly true for the Mediterranean ecosystems, where plant communities are characterized by high specific and structural heterogeneity and complexity, determined by the interaction of sub-arid Mediterranean climate and human factors. Therefore, to perform FARSITE calibration, the choice of the appropriate standard fuel models or the development of specific custom fuel models are required. In addition, the capabilities of FARSITE simulator can be affected by other environmental characteristics, as complex steep terrains with the resulting high spatial and temporal variability of wind speed and direction. In this work, FARSITE was employed to simulate spread and behaviour of four real fires occurred in North Sardinia during 2003, 2004 and 2006 summer seasons. The effect of fuel models, weather conditions and topography on the accuracy of FARSITE simulations was evaluated in order to assess the capabilities of the simulator in accurately forecasting the fire spread and behaviour in areas covered by Mediterranean maquis. A custom fuel model, designed and developed by our working group for maquis, provided realistic values of simulated fire behaviour. Improvements on the accuracy of both fire spread and behaviour were also obtained using raster maps of wind speed and direction. The results confirm that the use of both accurate wind field data and appropriate custom fuel models is crucial to obtain accurate simulations of fire behaviour occurring on Mediterranean vegetation during the drought season, when most wildfires occur.