Characterization and mapping of wildland urban interfaces, assessing forest fire risk in South of France

Forest fire risk concerns large territories and causes great damages with ecological, social and economical consequences but also with high costs of prevention and fire fighting. Forest fire risk increases because of dynamics of land cover and deep land transformations have been observed for some decades in the Mediterranean region. On the one hand agricultural fallows and orchards are slowly colonized by vegetation, on the other hand forest is not exploited enough; both conducting to the fuel load accumulation. Besides, especially in the South of France, the urbanization, joined to the forest extension phenomenon, generates new spatial configurations called wildland urban interfaces (WUI). WUI concerns integrate "natural" vegetation massifs connected to urban systems which bring out both components of forest fire risk: hazard and vulnerability. To assess fire risk in WUI is a need for wildfire prevention and land management. Considering that a level of fire risk can be affected to each type of wildland urban interface, how can we objectively characterize these WUI types? How can we set their boundaries to map them over wide areas and at a scale fit to regional development? How to establish relationships between fire risk level and WUI types? The aim of the paper is firstly to present a spatial analysis method to characterize wildland urban interface types and to map them from very high resolution satellite imagery. This method uses remote sensing in order to produce land cover map, spatial analysis support. It also uses ecological indices, shape indices associated to house density calculations. Then GIS allows to map WUI on wide areas and at a large scale. Secondly it is to present an approach of fire risk in wildland urban interfaces allowing to qualify interface typology in terms of fire risk levels. The methodology is applied on a case study area in the South of France.