Conference paper

GIS-based 3D modelling for landslide hazard assessment: increasing the objectivity of hazard maps.

Recent decades have been marked by many disasters caused by natural hazards.Gravitational phenomena in particular have resulted in several deaths and extensive damage to infrastructure. Nearly 10% of Swiss territory is considered unstable. It therefore requires an effective methodology for the mapping of areas likely to be affected by this type of hazard. The aim of this project is to establish the bedrock of a new methodology for the implementation of hazard maps related to landslides based on the evaluation of slope instability predisposition. The first step of this methodology is a systematic field survey on a given study area. The information is organized by type (faults, dip, formations, boreholes, springs, streams, etc..) and then imported into a GIS. Once these data interpolated and converted into a grid of points, we obtain on the one hand a three-dimensional geological model (supplemented by geotechnical and hydrodynamic parameters measured in situ and extrapolated to the entire study area) and on the other hand an approximation of the gradient of hydraulic potential in the area.It is then possible to calculate a safety factor at each point of the model and thus to assess the susceptibility of the slope to instabilities. After crossing with a map of moderating factors (altitude, aspect, vegetation) in order to take into account the context of the slopes, it is validated by comparison with the map of phenomena to obtain the final hazard map. Achieving it is thus entirely transparent.


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