Understanding the sensitivity to the soil properties and rainfall conditions of two physically-based slope stability models

Abstract

Physically-based models have been used to assess landslide susceptibility, hazard, and risk in many regions worldwide. They have also been regarded as valuable tools for landslide prediction and the development or improvement of landslide early warning systems. They are usually validated to demonstrate their predictive capacity, but they are not deeply studied regularly to understand the sensitivity of the input variables and the behavior of the models under many different rainfall scenarios. In this research paper, we studied two distributed physically-based models for shallow landslides: SLIP and Iverson. For this, the first-order second-moment (FOSM) method was used to calculate the contribution of random input variables (soil strength, unit weight, and permeability parameters) to the variance of the factor of safety. Different intensity and duration rainfall events were simulated to assess the response of the models to those rainfall conditions in terms of the factor of safety and failure probability. The results showed that the shear strength (cohesion and friction angle, in order of significance) parameters have the largest contribution to the variance in both models, but they vary depending on geological, geotechnical, and topographic conditions. The Iverson and SLIP models respond in different ways to the variation of rainfall conditions: for shorter durations (e.g. ≤ 8 h), increasing the intensity caused more unstable areas in the SLIP model, while for longer durations the unstable areas were considerably higher for the Iverson model. Understanding those behaviors can be useful for practical and appropriate implementation of the models in landslide assessment projects.

Landslide Susceptibility Analysis on the Vicinity of Bogotá-Villavicencio Road (Eastern Cordillera of the Colombian Andes)

“…Finally, Pradhan et al [51] and Ramos-Cañon et al [59] catalogued rock falls, avalanches, rotational and translational landslides, earth-mud flows and debris flows. In other parts of the country, such as the Western and Central Cordilleras, shallow slides, falls, debris flows and mud-flows have been identified [5,[24][25][26][27]29,45,50,55]; in the southern Colombian Massif, specifically in Mocoa, debris flows, debris avalanches and shallow slides have been found [8,21,30,31].…”

“…For hazard, there are numerous deterministic and probabilistic methods, the latter of which are generally the most applied for extensive areas due to the lack of precise and exhaustive data in such areas. Within the deterministic methods, different hydrological models [21,22] or stability analysis methods such as infinite slope [23], r.slope.stability of GRASS [24], FOSM [25][26][27], SLIP [26,27], PEM point estimates [25] or deformation analysis [28] have been applied. These models have been used in high-impact landslides such as the Mocoa debris flow in the southern part of the country [21,[29][30][31], hillslopes around Medellin [22] and San Eduardo in Boyacá [28] or watersheds such as La Arenosa and La Liboriana [24][25][26][27] in the department of Antioquia in the Western Cordillera.…”