Multi-regional landslide susceptibility mapping in the Federal Republic of Germany

The geological surveys of the federal states play a vital role in mitigating the impacts of landslides and safeguarding communities in Germany.
However, certain decisions require a cross-border approach to geohazard assessment, like the landslide susceptibility assessment (1:250 000 scale) that the Federal Company for Radioactive Waste Disposal commissioned. They requested it for areas, in which favorable geological conditions for the safe final disposal of high-level radioactive waste can be expected. To facilitate this we will homogenize state inventories and data from publications supported by state geological surveys (SGDs).
We will distinguish rockfall, translational, and rotational landslides in rule-based simplification steps. We will select specific methodology for each landslide type based on its causes, available information and best practices developed on the state level. For rockfall, we will estimate runout zones with the shadow angle method and identify source areas based on a critical slope angle, both derived from a digital elevation model (DEM) and calibrated against the landslide inventory. Translational landslides will be assessed using the infinite slope method, incorporating a nationwide soil map and a DEM. Geotechnical paramaters will be inferred via a pedotransfer function from the soil data, acknowledging associated uncertainties.

Rotational landslides will be evaluated with the Analytical Hierarchy Process to quantify regional expert knowledge from multiple parameters, because they are the least generalizable type. The available data will be used to define trivial areas. We aim to collaborate with SGDs and local experts to ensure technically sound and regionally adapted methodologies are used.