Geotechnical maps as input data for physically-based modelling of shallow landslide susceptibility
Shallow landslides are common geomorphological phenomena on mountain slopes in many regions of the world. Different kinds of susceptibility models have been proposed for the identification of areas particularly vulnerable to this natural hazard. Amongst these, physically-based slope stability models require detailed knowledge on the regolith characteristics of the total area of interest. Depending on the selected model, area-wide geotechnical and hydraulic parameters are required at an appropriate scale. Detailed studies carried out on a regional scale (e.g. covering catchments of several tens of square kilometres) demands intensive data acquisition. To meet these requirements a geotechnical map was prepared for the Laternser valley (Vorarlberg, Austria) in the course of an ongoing study on shallow landslide susceptibility. Construction of such geotechnical maps involves the understanding of the catchment’s complex landscape evolution, as it combines information on the spatial distribution of materials present and the occurrence of various (active or dormant) geomorphological processes. Geotechnically homogeneous units were identified, delineated and stored in a GIS. The information was based on integration of geological and geomorphological maps, remotely sensed data (including derivatives of airborne laser scanning (ALS) data, and aerial orthophoto time series) and reconnaissance surveys, geotechnically homogenous units were identified and delineated. For each geotechnical unit the relevant parameters (i.e. angle of internal friction, effective cohesion, soil depth and hydraulic conductivity) were derived from field inspections, laboratory experiments, existing soil maps and respective literature. The resulting ranges for each parameter form the building stones of a framework for scenario-based modelling of shallow landslide susceptibility on mountain catchment scale.
This work has been conducted within the project C3S-ISLS, which is funded by the Austrian Climate and Energy Fund, 5th ACRP Program.