Rainfall-induced landslides in Europe: hotspots and thresholds (Invited)
Abstract
This contribution presents preliminary results of the European project SafeLand. SafeLand is a large-scale integrating collaborative research project on landslide risks in Europe, funded by the Seventh Framework Programme for research and technological development (FP7) of the European Commission. SafeLand was launched in May 2009 and will run for three years. The project team, which comprises 27 institutions from 12 European countries, is coordinated by the International Centre for Geohazards (ICG) in Norway. SafeLand aims to develop and implement an integrated and comprehensive approach to help and guide decision-making in connection with mitigation of landslide risks. Quantifying the effects of global change (changes in demography and climate change) on evolution of landslide risk in Europe is one of the main goals of SafeLand. The methodologies are tested in selected hazard and risk "hotspots” in Europe, in turn improving knowledge, methodologies and integration strategies for the management of landslide risk. The present contribution is focused on two components of SafeLand: (1) the identification of landslide hazard and risk hotspots and (2) the estimation and assessment of rainfall thresholds for triggering of landslides. Hotspots of landslide hazard and risk were identified by an objective GIS-based analysis. The results show clearly where landslide pose the largest hazard in Europe and the objective approach allows a ranking of the countries by exposed area and population. In absolute numbers, Italy is the country with the highest amount of area and population exposed. Relative to absolute number of inhabitants and area, small alpine countries such as Lichtenstein and Montenegro score highest where as much as 40% of the population could be exposed. It is obvious that the type and quality of the input data are decisive for the quality of the results. Especially the estimation of extreme precipitation events needs improvement. These preliminary results are based only on one of three applied hazard models. The two other models are currently being evaluated. Empirical rainfall thresholds for landslide triggering have been estimated in selected locations in Italy, France, Switzerland and Norway. Six different empirical models were used. The datasets included landslide inventories as well as hourly or daily observations of precipitation. The types of events were predominantly soil slides and debris flows, a few rock slides and rock falls, and the acceleration of a slowly-moving landslide. The results indicate that the occurrence of soil slides and debris flows can be predicted using precipitation observations. On the other hand, empirical models based on rainfall characteristics fail to predict rock falls and rock slides, presumably due to the predominant influence of other triggering factors. Soil slides are controlled by a combination of antecedent precipitation for short and long periods (1-10 days and 1-5 months, respectively). Debris flows are controlled by short duration precipitation lasting less than 12 hours. Since the inventories contain events with uncertainty in time of occurrence (from a few hours to several days), an innovative procedure was implemented for the inclusion of this uncertainty in the estimation of thresholds.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2010
- Bibcode:
- 2010AGUFMNH31C..01C
- Keywords:
-
- 1826 HYDROLOGY / Geomorphology: hillslope;
- 1854 HYDROLOGY / Precipitation;
- 1952 INFORMATICS / Modeling;
- 9335 GEOGRAPHIC LOCATION / Europe