Prediction of changes in landslide rate induced by rainfalls: from the use of a black box model to a 1D mechanical model

Séverine Bernardie (1) , Nicolas Desramaut (1) , G. Russo (1) , J. Zurcher (1) , Gilles Grandjean (1)

1 BRGM - Bureau de Recherches Géologiques et Minières (BRGM)

This study focuses on an innovative methodology to predict landslide accelerations, based on a black box tool and a 1D mechanical model to predict the evolution of the daily displacements according to the variations of precipitation. More specifically, the impulse response model allows to predict the changes in the landslide rate by computing the transfer function between the input signal (precipitation in this case) and the output signal (the displacements). The second model uses a simple 1D mechanical model, with con-sidering a viscoplastic behavior of the landslide, and with taking into account the evolution of the pore water pressure. These methods have been applied to the Super-Sauze landslide, which takes place in the Southern French Alps, mountainous region. This site is controlled by the active movement within black marls, with velocities ranging between 0.002 and 0.4 m per day. The results show that the snowmelt has to be taken into account in the models, since the phenomena of freezing /thawing has an influence on the water refills, leading to changes in the movement. The approaches are compared and their complementarity is demonstrated in this study. It results in the development of a methodology for predicting changes in landslide rate based on criteria of com-parison between the observed and calculated velocities. The results suggest that the impulse response model reproduces the observed data with very good accuracy, whereas the mechanical model seems to be more adapted to predict the movements within 10 days. Moreover, the RMSE criterion permits to highlight the oc-currence of the flow, with considering all models, 11 days before the flow itself.

Domaines: Sciences de l'environnement

Séverine Bernardie, Nicolas Desramaut, G. Russo, J. Zurcher, Gilles Grandjean. Prediction of changes in landslide rate induced by rainfalls: from the use of a black box model to a 1D mechanical model. Journées Aléa Gravitaire, JAG 2011, Sep 2011, Strasbourg, France. p. 117-122. ⟨hal-00997046⟩