Harmonised Approaches for Landslide Susceptibility Mapping in Europe

The EU Thematic Strategy for Soil Protection and the associated Proposal for a Soil Framework Directive establish a framework to prevent further soil degradation and preserve its functions including the capacity of development of human activities. This framework first suggests identifying the areas in Europe where a number of soil threats including landslides are likely to occur by using a comparable approach based on the use of common thematic data. In this context, the European Landslides Expert Group hosted by JRC has developed guidelines and obtained preliminary results from harmonised susceptibility assessment and mapping in Europe at various scales using geographically-nested, multi-step Tier approaches. In these approaches, areas identified as of high susceptibility in the initial Tier (Tier 1) are subsequently assessed and mapped at larger scale and higher accuracy by successive Tiers (Tier 2 and 3). Preliminary harmonised European-wide generic landslide susceptibility mapping at 1:1 Mil. scale has been performed in Tier 1 by calibrating bivariate information values for a reduced number of already available pan-European datasets representing landslide conditioning factors. Since no harmonised landslide inventory is available for the whole continent, model production is performed using available landslide information in a number of countries. The first results show a relatively good performance of the model in many areas at this synoptic scale, but better results are expected in the near future. The importance of sufficient and well-distributed landslide information for model calibration is confirmed from a Tier 1 heuristic approach developed and applied to France. A Tier 2 landslide susceptibility assessment is recommended in areas of high susceptibility as identified by Tier 1, using a quantitative model and landslide inventory data. This approach is shown to be appropriate for national or regional scale mapping (1:1 Mil. to 1:250,000). A Tier 2 experiment has been carried out for Italy using a multivariate statistical model and a higher number of variables. In addition, separate temporal datasets from the AVI historical landslide database of Italy have been used for training and validation of the model. Finally, some recommendations for Tier 3 susceptibility mapping at local scale are provided.JRC.DDG.H.7-Land management and natural hazard