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Landslide Susceptibility Mapping at National Scale: The Italian Case Study

Landslide susceptibility maps are key tools for land use planning, management and risk mitigation. The Landslide susceptibility map of Italy, scale 1:1,000,000 is being realized by using the Italian Landslide Inventory – Progetto IFFI and a set of contributing factors, such as surface parameters derived from 20 to20 m DEM, lithological map obtained from the geological map of Italy 1:500,000, and land use map (Corine Land Cover 2000). These databases have been subjected to a quality analysis with the aim of assessing the completeness, homogeneity and reliability of data, and identifying representative areas which may be used as training and test areas for the implementation of landslide susceptibility models. In order to implement the models, physiographic domains of homogeneous geology and geomorphology have been identified, and landslides have been divided into three main classes in order to take into account specific sets of conditioning factors: (a) rockfalls and rock-avalanches; (b) slow mass movements, (c) debris flows. The modelling tests performed with different techniques (Discriminant Anaysis, Logistic Regression, Bayesian Tree Random Forest) provided good results, once applied with the appropriate selection of training and validations sets and with a significant number of statistical units.

Key Issues in Rock Fall Modeling, Hazard and Risk Assessment for Rockfall Protection

Rockfalls pose a significant threat to life and property, thus rockfall protection is a major issue in areas exposed to severe rockfall hazard. Rockfall protection approaches include quantitative rockfall hazard and risk assessment, as well as the design of structural countermeasures. These require a sound and robust quantification of 3D rockfall trajectories, distribution and intensity of impacts, and magnitude and variability of involved dynamic quantities. Providing highly reliable modeling inputs to rockfall protection remains a difficult task, because of the complexity and intrinsic stochastic nature of rockfall physics and the uncertainty of all the relevant parameters. However, significant advances in rockfall analysis have been made in the last decade, and modern 3D rockfall modeling techniques now provide effective tools to support rockfall protection activities, even in difficult design conditions. Nevertheless, their use can still be complex and raises a series of difficult steps both in the modeling and the analysis of the results. In this paper, we provide an overview of rockfall analysis aspects relevant to rockfall protection, as well as examples of applications of modern 3D rockfall runout modeling techniques in rockfall hazard and risk assessment, and countermeasure selection, design and optimization.

Analysis of Rockfall Individual Risk at the Feifeng Underground Caves (Zhejiang Province, China) by Using 2D and 3D Runout Models

The Feifeng Mountain tourist resort is famous for the ancient caves and drifting activities along the Yongan River. Because of steep slope, lithology (tuff overlying a thick soft layer), tectonic structure, and the underground excavation in ancient times, the area is seriously affected by rockfalls. A quantitative rockfall individual risk assessment has been performed, by using either a 2D and a 3D modelling approach. The 2D approach results in an overestimation of risk along the a priori defined paths, due to the impossibility to consider lateral spread of rockfall trajectories. The 3D approach allows for simulating the lateral dispersion and the trajectories along convergent topography, locally increasing the Individual Risk level.