PERFORMANCE CHECK OF CODES FOR REGIONAL SCALE ANALYSIS Sample Clauses

PERFORMANCE CHECK OF CODES FOR REGIONAL SCALE ANALYSIS. (UNISA) At medium-large scale (Xxxx et al. 2008a, 2008b), a promising approach for the susceptibility analysis of the rainfall-induced shallow landslides source areas relies on the use of the so- called physically based models for their capability in reproducing the physical processes governing the landslides occurrence. Moreover, their general grid-based structure and the wide availability of Geographic Information Systems provide a convenient framework that allows the susceptibility analysis over broad areas. Although these models have been already presented and discussed in deliverable D1.2, it is worthwhile to summarise some of their main characteristics, in order to allow a better understanding of their performance in the analysis of a relevant case study, which represents the object of the current section. Physically based models generally couple a hydrologic model, for the analysis of pore water pressure regime, with an infinite slope stability model for the computation of the Factor of Safety. These models rely on several simplifying assumptions that limit their applicability. Particularly, steady or quasi-steady models (x.x. Xxxxxxxxxx and Xxxxxxxx 1994; Xx and Xxxxx 1995) are limited to few unrealistic situations related to both rainfall characteristics and in situ conditions (Xxxxxxx 2000). Transient models, used either in saturated or unsaturated conditions of soils, are able to improve the effectiveness of susceptibility analysis, accounting for the transient effects of varying rainfall on slope stability conditions (x.x. Xxxx et al. 2002, 2008; Xxxxxx and Xxxxxxxx 2003; Xxxxxxx 2000; Xxxxxx et al. 2004), but they generally need abundant and accurate spatial information. Moreover, they are sensitive to some of the required input data such as hydraulic properties of soils, initial steady-state groundwater conditions and soil depths, whose correct evaluation is often possible only using empirical models or inverse deterministic analyses (Xxxx et al. 2008; Xxxxxxxxxx et al. 2006; Xxxxxxx et al. 2007). In order to achieve significant results, the application of physically based models requires a deep understanding of the conceptual assumptions, the accurate definition over broad regions of the in situ conditions of soils, of the pore pressure regime characteristics, as well as of the different triggering mechanisms. Moreover, a critical interpretation of results needs a methodology based on the use of quantitative indexes (Xxxxxx and Xxxxxxxx 2003...