A Novel Approach to Integrate Effects of Vegetation Changes on Slope Stability

Global changes would have direct impacts on landslide activities through the modifications of triggering events with the evolutions of climate forcing. However, some predisposing factors would also evolve. Indeed, forests are likely to be modified, either by anthropogenic interventions, natural ageing or adaptation to climate change. This evolution is likely to result in changes of slopes susceptibilities to landslides. In order to propose adequate solutions for current and future forestry management, it is therefore necessary to properly estimate the influences of the vegetation on slope stabilities. In the present study, we develop a complementary module to our large-scale slope stability assessment tool to take into account the effects of vegetation on the mechanical soil properties (cohesion and over-load), but also on the slope hydrology (change in interceptions, run-off, and infiltration). Hence the proposed method combines a mechanical stability model (using finite slope analysis), a hydrological model, and a vegetation module which interfere with both aspects. All these elements are interfaced within a GIS–based solution. Uncertainties on input data are propagated in the models through distributions laws. The method has first been applied to a Pyrenean Valley, a site which is part of the Observatoire Pyreneen du Changement Climatique (OPCC). A second application is being undertaken on another Pyrenean Valley, for the ANR Project SAMCO.