A GEOTECHNICAL-HYDROLOGICAL APPROACH FOR DEFINING CRITICAL RAINFALL-INDUCED SHALLOW LANDSLIDES AND WARNING SYSTEM AT LARGE SCALE

Abstract

This study proposes a novel method that combines deterministic slope stability model and hydrological approach for predicting critical rainfall-induced shallow landslides. The method first uses the slope stability model to identify “where” slope instability will occur potentially; the catchment is characterized into stability classes according to critical soil saturation index. The critical saturated soil index is calculated from local topographic components and soil attributes. Then, spatial distribution of critical rainfall is determined based on a hydrological approach under near-steady state condition as a function of local critical saturated soil depth, slope geometric, and upstream contributing drainage areas. The critical rainfall mapping is bounded by theoretically “always stable” and “always unstable” areas. To show how the method works, observed landslides (1985-2008) and a satellite-based rainfall estimates associated with a past new shallow landslide in the Upper Citarum River catchment (Indonesia) were used to validate the model. The proposed study is useful for rainfall triggered shallow landslide disaster warning at large catchment scale.

Keywords: Critical rainfall, slope stability, hydrology, shallow landslide, Citarum River catchment