Evaluation and cartography of the risk of forest fires - Towards an application at the Massif des Maures (in the South East of France) on the scale of the Plans for the Prevention of natural Risks (PPR)

Abstract

In the Mediterranean area, 10 000 to 60 000 ha of natural field are burnt every year. As a result, it is a permanent threat for goods and persons safety and for natural resources protection. So fire hazard prevention remains an important objective for the local communities, the State and the European Commission in the Mediterranean countries. In this context, the team « Forest Fire protection » of the Cemagref of Aix-en-Provence, developed a spatial analysis method to estimate forest fire hazard on the Maures Mountains (Var Department). The objective was to establish a cartography of the areas of same sensibility to fire. The change to a more accurate evaluation and cartography (particularly at the scale of the Risk prevention Plans) leads to questioning the implementation details of this method. The method proposed here proceeds in three steps, qualifying and mapping the areas of ignition, the areas of initial propagation of fire and the areas of free propagation. For each step, we make some hypothesis. The factors retained at the Mountain scale are analysed at the scale of 1/10 000. Some factors are combined in intermediate indices: that is the case for the vectorial combination of wind and relief. Limits are determined from expert knowledge and literature. Those limits correspond to different hazard levels. The results take the form of a determining key. A cartographic example is given after simulation on a Geographic information System.