Harmonized mapping of forests with a protection function against rockfalls over European Alpine countries

S. Dupire (1, 2) , D. Toe (1) , J.-B. Barré (1) , Franck Bourrier (3) , F. Berger (1)

1 UR LESSEM - Laboratoire des EcoSystèmes et des Sociétés en Montagne
2 SylvaLab
3 UR ETGR (ETNA) - Erosion torrentielle neige et avalanches

Forest covers 40% of the European Alpine region and contributes to the protection of human beings and infrastructures against natural hazards such as rockfalls. However, despite the recognition of this ecosystem service, most mountain territories do not have a map of protection forests. When a map exists, it generally depends on data restricted to a limited extent, which prevents any replication or comparison on other areas. The aim of this study is to develop a method using harmonized and open data to produce the first map of protection forests against rockfalls at the European Alpine region scale. Based on these data, we first identified potential rockfall release areas and calibrated the model according to 2812 real rockfall events located around the Alps. Second, 46.5 billion 3-D rockfall propagation simulations, taking into account topography, land use and human assets, were computed on the entire area. Protection forest is defined as being located on at least one rockfall trajectory that had impacted human assets. Our results show that 14% of the forests have a potential protection function against rockfalls in the Alpine Space region. This proportion goes up to 21.5%, if we consider only the core of the Alpine area. 80% of the protection forest area contributes to mitigate rockfall hazard on road network, 55% on buildings and only 6% on railways. This work provides a robust, objective and reproducible method for locating protection forests on a large geographical scale. Such a map may serve as a basis for national and European risk management policies.

Mots clés: Protection forests; Rockfall; Mapping; Ecosystem services; Alps; Natural hazard

Domaines: Ingénierie de l'environnement; Géophysique [physics.geo-ph]; Météorologie; Climatologie; Risques; Environnement et Société; Ecosystèmes; Bioclimatologie; Biodiversité et Ecologie; Milieux et Changements globaux; Sylviculture, foresterie; Géomorphologie

S. Dupire, D. Toe, J.-B. Barré, Franck Bourrier, F. Berger. Harmonized mapping of forests with a protection function against rockfalls over European Alpine countries. Applied Geography, 2020, 120, pp.11/102221. ⟨10.1016/j.apgeog.2020.102221⟩. ⟨hal-02519495v2⟩