Characterization of Critical Rainfall for Slopes Prone to Rainfall-Induced Landslides

The paper presents a procedural method to characterize critical rainfall for slopes affected by rainfall. For regions where landslide risk is high and landslide prediction alone is not acceptable, correction of existing landslides caused by rainfall requires inclusion of potential driving forces due to rainfall in the slope design. This can be accomplished by identifying critical rainfall for slope. Although many rainfall thresholds in the literature give a range of rainfall values critical for a slope, it is difficult to identify the exact class of rainfall that functions as the critical rainfall from these thresholds. In this study, critical rainfall was determined based on a rainfall threshold developed using the forecasting of landslides induced by rainfall (FLaIR) model, information on historical landslides, and rainfall infiltration analyses. The proposed method was applied to an area in northeastern India.