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 in vestigate the interrelationship between landslides, climate and time. The r esearch was focused on three main objectives: (I) developing criteria for t he recognition of landslides, (2) reconstructing past distributions of land slide 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 hydro logical and slope stability models. Landslide activity since 1950 has been generally high at all test sites. In some areas, there has almost been a co ntinuous activity observed since the beginning of the monitoring. The recor ds before 1950 are incomplete and probably indicate a lack of data rather t han a lack of landslide activity. Whether the observed active landslides ar e carrying a climate signal cannot be stated for all test sites with high c onfidence, since some relationships between climate and landslides are unce rtain. Thus, for the present, the complexity of the relationships between c limate and landsliding seems to make it not feasible to establish "universa l laws'' all over Europe. On the other hand, it was possible to establish f or some areas a cumulative rainfall-duration threshold for the reactivation of landslides. Future scenarios of regional precipitation were derived fro m downscaled general circulation model (GCM) experiments and used within si mple slope hydrological and slope stability models. The evaluation of hydro logical and slope stability models shows that physically based models are n ot always the best solution due to the model complexity and data requiremen ts. For shallow landslides, more simple tank models are sometimes the bette r alternative. Future model development should strengthen considerations of fissure flow, sudden changes in permeability, larger landslide volumes and complex landslide topography. (C) 1999 Elsevier Science B.V. All rights re served.