Multi-stage statistical landslide hazard analysis: Rain-induced landslides

Abstract

Recurrence of rain-induced landslides is controlled by the repetition of rain events. Therefore, rainfall induced landslide hazard analysis is more complicated than a conventional rainfall frequency analysis, and requires multi-stage procedures. It requires a susceptibility analysis to divide a region into successive classes at the first stage. Then, the relationship between the probability of landslide failure and rainfall intensity and/or total rainfall of an event for each susceptibility classes may be constructed, and further fit a probability of failure surface using the susceptibility value, rainfall intensity and/or total rainfall as independent variables. Then, frequency analysis for rainfall parameters at different return periods is performed. Finally, an analysis of the spatial probability of landslide failure under a certain return-period rainfall is drawn. This study selects data for Typhoon Haitang induced landslides in the Kaopin river basin as the training data set to perform a susceptibility analysis and a probability of failure surface analysis. A rainfall frequency analysis is also conducted to map different return-period rainfall intensity and 3-day rainfalls. Finally, a rainfall landslide hazard map is provided.