Spatially-distributed assessment of sediment yield and shallow landslide potential area in the upper Citarum River basin, Indonesia

Frequently, only a few locations within a basin are critical and responsible for high amounts of soil loss due to surface soil erosion and shallow landslide events. In connection with sediment yield reduction programmes, effective control of soil losses requires implementation of best management practices (BMPs). For the effective and efficient implementation of BMPs, identification of such critical locations is essential. In this study a physically-based hydrological-geotechnical model was applied to an upland tropical basin, with the aim of providing an assessment tool for identification of critical sub-basins. The model consists of two primary components. These comprise a hillslope sediment-runoff component, which considers soil detachments by rain and surface runoff; and a stochastic slope instability algorithm. Daily streamflow and suspended sediment discharge data, as well as the spatial patterns of documented historical landslides, were used for model evaluation and application. Critical sub-basins were identified on the basis of spatially-distributed sediment yields and areas predicted as susceptible to shallow landsliding. The study demonstrated the high potential applicability of the proposed modelling approach for identifying areas vulnerable to erosion and thus important sediment sources.