Mar 14 2016

Suitability of Lidar for the assessment of forest protection effect against rockfall

This article shows that the methodologies tested in the Newfor project for forest resource mapping also have wider applications in mountain management, e.g. natural risks.

Monnet, J.-M., Bourrier, F., Dupire, S., Berger, F. 2016. Suitability of airborne laser scanning for the assessment of forest protection effect against rockfall. Landslides. PDF

DOI 10.1007/s10346-016-0687-5

Rockfall simulation models are now able to quantify the protective effect of forest with the integration of rock impacts on trees. Those models require spatially explicit forest characteristics which are costly to acquire in operational conditions. The present study compares rockfall simulation results obtained with different forest input data sources: field data with different levels of spatial detail and two methods based on airborne Lidar data. Three different forest stands are tested with several virtual terrain configurations. When rockfall energies are below 200 kJ, the forest protection effect is significant. For higher energies, it also exists but it is minor compared to the effects of topography and rock volume. For all forest input data sources, the estimated rockfall intensity is within −13 and +16 % of the reference value, whereas the frequency is generally overestimated. Both Lidar methods yield a satisfactory forest protection effect evaluation, but single tree detection tends to underestimate it. Improvements are possible regarding the spatial heterogeneity of stem density and the diameter distribution by tree species.