Estimating the effects of heavy rainfall conditions on shallow landslides using a distributed landslide conceptual model

This study used a distributed landslide conceptual model to examine the effects of variable, heavy-rainfall conditions on shallow landslides. A digital terrain model with 50-m resolution was used to calculate the regional potential for shallow landslides based on the distribution of shallow infiltration water, Darcy’s law, and a safety factor estimated by infinite slope stability analysis. The model was applied to the upper Miyagawa River basin at Odai-cho in Mie Prefecture, Japan. In 2004, Typhoon Meari caused severe landslides in areas adjacent to the study area, whereas other heavy-rainfall events in the same year did not cause severe landslides. Response analysis of data collected hourly during heavy-rainfall events revealed that temporal changes in shallow landslide potentials were influenced by both temporal rainfall patterns and effective soil cohesion. Two indices obtained from the model were found to be useful for discriminating between rainstorms with and without sediment-related disasters.

► We examine the effects of heavy rainfall on landslides with a conceptual model.
► This model consists of a groundwater calculation and an infinite-slope analysis.
► The difference among rainstorms is influenced by changes in the soil cohesion.
► The back analysis is valid to discriminate which rainstorms triggered landslides.