The Relevance of Geotechnical-Unit Characterization for Landslide-Susceptibility Mapping with SHALSTAB

Abstract

Given the increasing occurrence of landslides worldwide, the improvement of predictive models for landslide mapping is needed. Despite the influence of geotechnical parameters on SHALSTAB model outputs, there is a lack of research on models’ performance when considering different variables. In particular, the role of geotechnical units (i.e., areas with common soil and lithology) is understudied. Indeed, the original SHALSTAB model considers that the whole basin has homogeneous soil. This can lead to the under-or-overestimation of landslide hazards. Therefore, in this study, we aimed to investigate the advantages of incorporating geotechnical units as a variable in contrast to the original model. By using locally sampled geotechnical data, 13 slope-instability scenarios were simulated for the Jaguar creek basin, Brazil. This allowed us to verify the sensitivity of the model to different input variables and assumptions. To evaluate the model performance, we used the Success Index, Error Index, ROC curve, and a new performance index: the Detective Performance Index of Unstable Areas. The best model performance was obtained in the scenario with discretized geotechnical units’ values and the largest sample size. Results indicate the importance of properly characterizing the geotechnical units when using SHALSTAB. Hence, future applications should consider this to improve models’ predictivity.

Avaliação Da Susceptibilidade a Escorregamentos Translacionais Em Maquiné/Rs E Influência Dos Dados De Campo Na Qualidade Do Mapeamento De Perigo

“…O resultado obtido pelo cenário 3 demonstra a importância de conhecer as informações geotécnicas locais ao aplicar um modelo como o SHALSTAB, a aplicação desse modelo com as informações padrões ou com dados da literatura deve ser somente em análises preliminares, para um estudo/mapeamento mais criterioso devem ser coletadas as informações geotécnicas locais. Essa importância do mapeamento geotécnico foi demonstrada com bastante ênfase por Melo et al (2021)…”

“…No entanto, os autores utilizaram os mesmos dados para toda a bacia, sem diferenciar as propriedades do solo entre as unidades geotécnicas (UGs) existentes nas áreas analisadas. A segregação da bacia em UGs fornece resultados mais próximos da realidade, pois cada UG possui uma resistência mecânica diferente e apresenta um comportamento hidrológico diferente (MELO et al, 2021).…”

Avaliação Da Influência Da Resolução Do Modelo Digital De Terreno Na Modelagem Numérica De Escorregamentos E Fluxo De Detritos.

“…Os parâmetros de Cs e φ podem ser obtidos através de ensaios de cisalhamento nas regiões de estudo, e sua caracterização é muito importante no mapeamento de áreas susceptíveis (MELO et al, 2021) próximo ao de Igrejinha. Aqui se salienta que as características do solo são bastante similares entre esses dois municípios.…”

An integral assessment of landslide dams generated by the occurrence of rainfall-induced landslide and debris flow hazard chain

“…These models evaluate the spatial distribution of the hazard in terms of Factor of Safety (FoS) for rainfall-induced landslides (Chikalamo, 2018), applying infinite slope models which make them mostly applicable for the analysis of shallow landslides. The TRIGRS model considers partially saturated conditions and transient flows (Aristizábal et al, 2022;Rana and Babu, 2022); SHALSTAB model assumes that local surface topography is the dominant control of landslide occurrence, which makes it appealing for DEM-based landslide analyses (Moreira Melo et al, 2021); FSLAM was developed to calculate large areas (>100 km 2 ) with a highresolution topography in a very short computational time (Medina et al, 2021). This model includes two different submodels: the hydrological model, which calculated the rainfall infiltration into the soil layer and the resulting position of the water table, and the geotechnical model, which applies the widely used infinite slope theory to calculate the slope stability (Guo Z. et al, 2022;Hürlimann et al, 2022); EPADYM model calculates the reliability index, failure probability and stability factor of a slope under seismic and static conditions (Hidalgo and Vega, 2021).…”