Expliquer la variation spatio-saisonnière des feux par leurs causes : le cas du sud-est de la France.

[Departement_IRSTEA]Territoires [TR1_IRSTEA]SEDYVIN [ADD1_IRSTEA]Adaptation des territoires au changement globalInternational audienceThis paper explains the spatial variation of the fire metrics throughout SE France which was divided into three regions, each characterized by environmental and socio-economic trends. The most deleterious causes were identified as well as their evolution throughout the year. Using the regional fire database Prométhée, which has gathered information on wildfires in SE France since 1973, different fire metrics such as occurrence, burned area have been investigated in the study area. A general trend was identified in SE France showing that most fires occurred and had the highest impact, in terms of burned area, in summer. When the fire causes were known (only 33.7% of the total ignitions), undetermined arson and negligence during professional work were the most frequently involved. However, because of the interactions between region, season, and cause, the fire metrics could differ from this trend, varying spatially and seasonally according to their cause. Fires due to deliberate causes (especially undetermined arson) were concentrated and impacted mainly region 3 in summer, usually presenting a large mean burned area. In contrast, unintentional fires due to forestry and agricultural works were gathered and had a higher impact mainly in region 1 in winter, and fires due to private work, smaller in size, presented the same pattern but occurred mainly in spring in region 3. This pattern was mainly due to the seasonality of these works. The spatioseasonal variation of natural (lightning) and accidental fires (especially due to power lines and garbage dumps) were mainly driven by climate conditions (regarding lightning and power lines) and/or population density (regarding garbage dumps). When fires smaller than 1ha were removed from the analyses, results could differ regarding the region or season of maximum occurrence and/or mean burned area for fires due to lightning, professional works and negligence during leisure activities. Locating the hotspots of fire occurrence for the main causes will help to improve fire prevention in better allocating law-enforcement and educational measures