Estimating the Influence of Rainstorms on Shallow Landslides: Comparison of the Intensity-duration Method and a Distributed-landslide Conceptual Model

Abstract

In this study, two methods were used to examine the influence of rainstorms on landslides. The first method used mean rainfall intensity and duration (I-D), and the second used a distributed-landslide conceptual model based on the distribution of shallow-infiltration water and a safety factor estimated using infinite slope-stability analysis. These two methods were applied to the Utsunomiya University forest in Funyu, Tochigi, Japan. Two indices were used to discriminate between rainstorms with and without landslides: one indicated the effect of short-duration events on landslide occurrence, and the other reflected the effect of the duration of an entire rainfall event on landslide occurrence. Although the indices derived using the two methods produced similar estimated effects of rainstorms on landslides, confirming the validity of both approaches for the estimation of rainfall properties, the two indices were better correlated with the distributed-landslide conceptual model than with the I-D, suggesting the superiority of the former model.