References

NHESS

Natural Hazards and Earth System Sciences

NHESS

Nat. Hazards Earth Syst. Sci.

1684-9981

Copernicus Publications

Göttingen, Germany

10.5194/nhess-13-3169-2013

Shallow landslide's stochastic risk modelling based on the precipitation event of August 2005 in Switzerland: results and implications

Nicolet

https://orcid.org/0000-0001-8777-9472

¹ Foresti

¹ ² Caspar

¹ Jaboyedoff

https://orcid.org/0000-0002-6419-695X

Center of Research on Terrestrial Environment, University of Lausanne, Lausanne, Switzerland

Royal Meteorological Institute of Belgium, Brussels, Belgium

09 12 2013

13 12 3169 3184

2013

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Due to their relatively unpredictable characteristics, shallow landslides represent a risk for human infrastructures. Multiple shallow landslides can be triggered by widespread intense precipitation events. The event of August 2005 in Switzerland is used in order to propose a risk model to predict the expected number of landslides based on the precipitation amounts and lithological units. The spatial distribution of rainfall is characterized by merging data coming from operational weather radars and a dense network of rain gauges with an artificial neural network. Lithologies are grouped into four main units, with similar characteristics. Then, from a landslide inventory containing more than 5000 landslides, a probabilistic relation linking the precipitation amount and the lithology to the number of landslides in a 1 km<sup>2</sup> cell, is derived. In a next step, this relation is used to randomly redistribute the landslides using Monte Carlo simulations. The probability for a landslide to reach a building is assessed using stochastic geometry and the damage cost is assessed from the estimated mean damage cost using an exponential distribution to account for the variability. Although the model reproduces well the number of landslides, the number of affected buildings is underestimated. This seems to result from the human influence on landslide occurrence. Such a model might be useful to characterize the risk resulting from shallow landslides and its variability.

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