Eric Maillé

Wildland–urban interfaces (WUIs) are critical zones for wildfire prevention in Mediterranean and semi-arid landscapes, particularly where human settlements interact with continuous combustible vegetation. In Algeria, operational tools for delineating WUI configurations and spatially prioritizing preventive actions remain limited. This study develops a GIS-based structural wildfire-risk prioritization framework for the Djebel El Ouahch massif (Constantine, northeastern Algeria) by combining WUIMAP II settlement typologies with an Aggregation Index (AI) describing the horizontal continuity of arboreal and shrub vegetation derived from Sentinel−2 data. Built-up structures were classified as isolated housing, dispersed housing, main urbanized areas, or peripheral zones and combined with three AI classes to delineate relative structural-priority areas. Dispersed and isolated housing accounted for 55% and 37% of mapped housing structures, respectively, while the WUI contained an estimated 18,100 inhabitants distributed across 3620 housing units. The resulting WUI × AI structural-priority layer covered 0.863 km², of which high- and very-high-priority zones jointly represented 0.544 km² (63.04%). These priority areas identify locations where structurally exposed settlement configurations coincide with greater horizontal fuel continuity, providing a spatial basis for targeted fuel management, surveillance planning, emergency-access improvement, and wildfire-prevention actions. By improving the spatial targeting of preventive measures, the framework can contribute to sustainable forest and land management, disaster-risk reduction, ecosystem protection, and the resilience of WUI settlements.

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.

INTERMED (Interventions pour gérer et réduire le risque d’incendie à l’interface habitat-espace naturel) deals with the fire risk at Wildland Urban Interface (WUI) and brings together Collectivité de Corse, University of Corsica, INRAE, University of Sassari, Regione Liguria, Associazione Nazionale Comuni Italiani Toscana and the Union of Municipalities of Versilia. The objective is to identify the fire risk at WUI and to define effective means to reduce their vulnerability. INTERMED is divided into three parts: The identification and mapping of fire risk at WUI, realized by the Collectivité de Corse, the University of Sassari and INRAE. This part develops methodologies for fire-risk assessment in the WUI areas and WUI fire-risk mapping at a fine scale, including both hazard and vulnerability components. The second part is an assessment of the vulnerability of buildings, linked to the vegetation around buildings, performed by the University of Corsica and INRAE. The objective is to provide recommendations for landscaping arrangements around buildings at WUI to reduce construction vulnerability. This part is based on real-scale experiments and numerical simulations. The third part is a test of pilot actions realized by Regione Liguria, Associazione Nazionale Comuni Italiani Toscana, INRAE and Union of Municipalities of Versilia. In this part, the following actions are proposed: the creation of the project platform for a Spatial Decision Support Tool to assess buildings’ vulnerability; the creation of small infrastructures to reduce the risk of WUI fires in a residential area of Quercianella; the creation of three firewise communities in the municipalities with high fire risk; the realization of a hazard map regrouping a susceptibility map and a potential fire-line intensity map; the purchase of a prototype vehicle to assist people in WUI areas and a telecommunication kit for fire fighters; finally, the creation of evacuation routes and safe waiting areas for tourists and citizens in the forest complex of the Pineta di Levante.

Forests represent both valuable and vulnerable natural resources because of the various ecosystem services they provide and their sensitivity to climate change and fires. In the Mediterranean region, the depth of transformations in the rural land use, with mass abandonment of traditional activities (farming, livestock raising, and forest utilization) and an acceleration of urban sprawl, has affected the impact of fires on the territory and especially on the wildland–urban interface (WUI). The objective of the present study is to generate maps of forest fire risk in the region of SUD-Provence-Alpes-Côte d'Azur (France), integrating natural factors (vegetation type, topography and meteorology conditions, etc.) and human factors related to the closeness to causative elements that can potentially be the ignition point of fires (transport and power infrastructures, settlements and scattered buildings, etc.). GIS spatial analysis was used to combine single influence factors in risk maps to display the total fire risk map. These maps could be especially helpful in land management and emergency planning to minimize the effects of forest fires.