The Impact of Hydrological Parameters on Modelling Slope Safety Factor Towards Shallow Landslides: A Case Study from Oltrepò Pavese

Abstract

Hydrological monitoring of slope susceptible to shallow landslides allows for identifying the triggering conditions of shallow failures and implementing slope stability analysis at site-specific scale. In this work, a case study of a long-term hydrological monitoring in a slope susceptible to shallow landslides of Oltrepò Pavese (Northern Italy) is presented. The triggering mechanism develops in wet seasons (winter and spring) due to the uprise of a perched water table at about 1 m from ground surface, in consequence of the most intense rainfalls (about > 60 mm in 48 h). Unstable conditions (safety factor < 1.0) are correctly modeled on the basis of both water content and pore water pressure, with a better prediction considering hysteresis effects. Safety factor on the basis of water content can correctly assess the triggering conditions for unsaturated and completely saturated soils. It is possible estimating shallow landslides triggering caused by positive pore water pressures only considering this parameter.