A new approach to integrate effects of changes in vegetation cover in slope stability assessment.

Vandromme Rosalie et Desramaut Nicolas

BRGM, Direction Risques et Prévention, 3 avenue Claude Guillemin, 45060 Orléans Cedex 2

Global changes would have direct impacts on landslide activities through the triggering events with the evolutions of the climate forcing. But the predisposing causal factors would also evolved, e.g. the effects of the induced changes on the vegetation covers. Indeed, the forests are likely to be modified, either by anthropogenic interventions, natural ageing or to adapt to climate change. And this evolution is likely to result in changes of the susceptibilities of slopes 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 the stabilities of the slopes. In the present study, we are developing a complementary module to our slope stability assessment tool to also consider the effects of vegetation on the hydrology of the slope (change in interceptions, run-off, and infiltration) but also on the mechanical properties of the soil (cohesion, over-load and wind induced pressure). Hence the proposed methodology will combine a mechanical stability analysis using finite slope analysis, with a hydrological model, a global 3 tank model, and with a vegetation module which interfere with both aspects. All these elements are interfaced with a GIS. The methodology will be applied in a Pyrenean Valley, in Laruns, a site which is part of the Observatoire Pyrénéen du changements climatiques.