New Developments in Harmonized Landslide Susceptibility Mapping over Europe in the Framework of the European Soil Thematic Strategy

Abstract

In the context of the European Soil Thematic Strategy, and the formulation of a draft of a European framework directive devoted to the sustainable use of soil, landslides are recognized as one of the eight soil threats requiring harmonized spatial hazard assessments over the EU territory. The general framework for such assessments consists of a nested geographical approach based on “Tiers”, where a low-resolution (1:1 Million) evaluation (“Tier 1”) using already available pan-European datasets should enable the delineation of priority areas requiring more detailed assessments with additional data (“Tier 2”). In this contribution, we present new developments in the elaboration of a “Tier 1” generic landslide susceptibility evaluation based on a heuristic modelling approach exploiting the most important landslide conditioning factors. Extensive landslide locations available at small spatial scales have been collected and harmonized over the EU territory to be used for input parameter specification and model calibration, evaluation and classification. Since the analyzed area is highly complex in terms of climato-physiographic conditions controlling landslide occurrences, a preliminary landslide terrain differentiation is proposed consisting of eight calibration zones where specific predictor class weights have been allocated through a heuristic indexing approach. The spatially combined preliminary pan-European susceptibility estimate classifies 13 % of the EU territory as prone to landslides, thus requiring more detailed, quantitative inventory-based susceptibility evaluations (“Tier 2”).