The temporal stability and activity of landslides in Europe with respect to climatic change (TESLEC): main objectives and results

The major aim of the European project “The temporal stability and activity of landslides in Europe with respect to climatic change (TESLEC)” was to investigate the interrelationship between landslides, climate and time. The research was focused on three main objectives: (1) developing criteria for the recognition of landslides, (2) reconstructing past distributions of landslide incidents and their relationship to climatic change parameters, and (3) developing a hydrological and slope stability modelling framework using different test sites. The results of the project are related to these major objectives and include: (1) a technical manual for landslide recognition, (2) records of landslide activity, and (3) an evaluation of different hydrological and slope stability models. Landslide activity since 1950 has been generally high at all test sites. In some areas, there has almost been a continuous activity observed since the beginning of the monitoring. The records before 1950 are incomplete and probably indicate a lack of data rather than a lack of landslide activity. Whether the observed active landslides are carrying a climate signal cannot be stated for all test sites with high confidence, since some relationships between climate and landslides are uncertain. Thus, for the present, the complexity of the relationships between climate and landsliding seems to make it not feasible to establish “universal laws” all over Europe. On the other hand, it was possible to establish for some areas a cumulative rainfall-duration threshold for the reactivation of landslides. Future scenarios of regional precipitation were derived from downscaled general circulation model (GCM) experiments and used within simple slope hydrological and slope stability models. The evaluation of hydrological and slope stability models shows that physically based models are not always the best solution due to the model complexity and data requirements. For shallow landslides, more simple tank models are sometimes the better alternative. Future model development should strengthen considerations of fissure flow, sudden changes in permeability, larger landslide volumes and complex landslide topography.