Regional Mapping of Forest with a Protection Function Against Rockfall

On mountain slopes, forest can play an important role to protect human lives and facilities against rockfalls. Silvicultural strategies and interventions to maintain or improve protection forest structures are of first interest. Up to now, regional mapping of protection forest does not exist in France. The objectives of the study are to develop decision support tools for rockfall protection forest management. This paper present a Geographic Information Systems (GIS) based model which automatically maps forests with a protection function against rockfall hazard. This model, called RollFree, is a statistical based model which calculated maximum run out zone of rockfall based on the energy line principle. RollFree presents the advantages of a fast computational time and need only few input parameters such as a DEM, a map of the issues and a map of the forest cover. In the French region of Rhone-Alpes, results showed that forests with a protection function against rockfall can represent up to 30 % of all the forests in the district. These maps can be used as a decisional tool by practitioner to develop management strategies in order to define priority zones for more accurate rockfall mapping and adapted protection forest management.