Journal cover Journal topic
Natural Hazards and Earth System Sciences An interactive open-access journal of the European Geosciences Union
Nat. Hazards Earth Syst. Sci., 15, 1025-1050, 2015
https://doi.org/10.5194/nhess-15-1025-2015
© Author(s) 2015. This work is distributed under
the Creative Commons Attribution 3.0 License.
Research article
21 May 2015
Site-specific to local-scale shallow landslides triggering zones assessment using TRIGRS
M. Bordoni1, C. Meisina1, R. Valentino2, M. Bittelli3, and S. Chersich1 1Department of Earth and Environmental Sciences, University of Pavia, Via Ferrata 1, 27100 Pavia, Italy
2Department of Civil and Environmental Engineering and Architecture, University of Parma, Viale G. P. Usberti 181/A, 43100 Parma, Italy
3Department of Agricultural Sciences, University of Bologna, Viale Fanin 44, 40127 Bologna, Italy
Abstract. Rainfall-induced shallow landslides are common phenomena in many parts of the world, affecting cultivation and infrastructure and sometimes causing human losses. Assessing the triggering zones of shallow landslides is fundamental for land planning at different scales. This work defines a reliable methodology to extend a slope stability analysis from the site-specific to local scale by using a well-established physically based model (TRIGRS-unsaturated). The model is initially applied to a sample slope and then to the surrounding 13.4 km2 area in Oltrepò Pavese (northern Italy). To obtain more reliable input data for the model, long-term hydro-meteorological monitoring has been carried out at the sample slope, which has been assumed to be representative of the study area. Field measurements identified the triggering mechanism of shallow failures and were used to verify the reliability of the model to obtain pore water pressure trends consistent with those measured during the monitoring activity. In this way, more reliable trends have been modelled for past landslide events, such as the April 2009 event that was assumed as a benchmark. The assessment of shallow landslide triggering zones obtained using TRIGRS-unsaturated for the benchmark event appears good for both the monitored slope and the whole study area, with better results when a pedological instead of geological zoning is considered at the regional scale. The sensitivity analyses of the influence of the soil input data show that the mean values of the soil properties give the best results in terms of the ratio between the true positive and false positive rates. The scheme followed in this work allows us to obtain better results in the assessment of shallow landslide triggering areas in terms of the reduction in the overestimation of unstable zones with respect to other distributed models applied in the past.

Citation: Bordoni, M., Meisina, C., Valentino, R., Bittelli, M., and Chersich, S.: Site-specific to local-scale shallow landslides triggering zones assessment using TRIGRS, Nat. Hazards Earth Syst. Sci., 15, 1025-1050, https://doi.org/10.5194/nhess-15-1025-2015, 2015.
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This manuscript defines a reliable methodology for shallow landslides triggering zones assessment at site-specific or local scales by using a well-established physically based model (TRIGRS-unsaturated) based on the calibration of the model at slope scale using soil hydrological behavior analyzed through a continuous field monitoring. Moreover, the paper analyzes the effects on triggering zones assessment of taking into account for different unit mapping of the slope soils of a studied area.
This manuscript defines a reliable methodology for shallow landslides triggering zones...
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