Christophe Bouillon

We designed and tested an expert opinion-based multi-criteria model for the assessment of several components of the wildfire risk, including ignition and outbreak hazards (the probability of ignition “success”), propagation hazard, as well as stakes exposure and vulnerability. The approach also allows formalizing the interaction between these components, in order to specify an integrated analytical risk model. The formal risk model is specified according to the IPCC 2014 conceptual framework, which structures the risk in hazard, vulnerability and exposure components. Only the structural risk is assessed, related to climate, fuel and land management, and not the daily risk (danger). The multicriteria method used in this demarche is the Analytic Hierarchy Process (AHP). The experts opinion-based approach is justified by the lack of spatially precise data related to past events, particularly ignition points and damages databases, while the fire contours are also sometimes imprecise. The model does not give any absolute value of risk, but only hierarchizes the different zones of a whole region in relation to their relative level of risk. The model has to be recalibrated for each context it is designed for, with new expert enquiries. The method was initially specified to the supra-Mediterranean area of a South Eastern France Natural Regional Parc (Parc Naturel Regional des Baronnies Provençales) and is now being calibrated to the MED-STAR/INTERMED French area. In a second step, each of the “atomic” models (for each component assessment) are being validated using statistical tools.

Global change is increasing concerns regarding fire risk, especially for the wildland–urban interface (WUI). Indeed, different cross-national funded projects aim to develop new methodologies and technologies for assessing and reducing fire risk at the WUI. Traditional approaches focused on multi-criteria decision analysis usually neglecting the interaction of multiple fine-scale components. Here, within the framework of the Italy–France Maritime INTERMED project, we develop a new fire risk assessment methodology following the IPCC guidelines, i.e., considering the three main risk determinants: hazard, exposure and vulnerability. Each single risk determinant integrates multiple components which were estimated using high-resolution data from the European Spatial Agency (ESA), field data, fire spread simulators and local administrations’ geo-data. Hazard components run at the local scale, involving weather and fuel moisture conditions, and also ignition patterns, whereas fire exposure components integrate both percolation and spot potentials (fire pathways and micro-scale land flammability) and postfrontal combustion (residential fuels). Finally, vulnerability components include the type of house and its configuration but also the existence of protection devices. Preliminary results suggest that this methodology might help fire risk planning in WUIs at both landscape and community scales.