Approaches for Delineating Areas Susceptible to Landslides in the Framework of the European Soil Thematic Strategy

In the framework of the European Soil Thematic Strategy, and the associated preparation of a directive on the protection and sustainable use of soil, landslides were recognized as a soil threat requiring specific strategies for risk assessment and management. The criteria for harmonized risk area delineation proposed by the Soil Information Working Group (SIWG) of the European Soil Bureau Network (ESBN) adopt a nested geographical approach based on “Tiers” and exploit thematic and environmental data of different type, quality, and resolution using a variety of methodological and technological approaches suitable for the spatial evaluation of any specific soil threat. The main requirement for a continent-wide “Tier 1” assessment for the delineation of areas subject to soil threats in Europe is the availability of relevant input data. At present, such a continent-wide assessment of landslide susceptibility in Europe is feasible only when adopting a qualitative evaluation technique since high-quality, pan-European landslide conditioningand triggering factor data is available, but a European-wide coverage of landslide locations is missing. “Tier 1” landslide susceptibility evaluations are described to serve for general risk/priority area identification and must at least be able to discriminate areas subjected to more detailed spatial assessments against those where no further action has to be taken. Quantitative evaluations of landslide susceptibility according to a “Tier 2” assessment require the availability of landslide inventory maps and databases. We outline the current advances towards the development of a common methodology for assessing the landslide threat in Europe. We refer to limitations, data needs and future work to be carried out, and present examples of nationwide assessments.