Exploring the association between landslides and fluvial suspended sediment in a semi-arid basin in central Chile

Abstract

The systematic monitoring of landslides is an essential input for their characterization and subsequent reduction of their risk. Along the western subtropical Andes, field monitoring is scarce, so alternative methods that can improve the monitoring are valuable. In this work, the capacity of fluvial suspended sediment to detect the occurrence of landslides in a basin was explored, emphasizing how the relationship varies depending on the hydro-sedimentological variable, the triggering causal factor and the landslide type. The values of suspended sediment concentration (SSC), water discharge (Q) and specific suspended sediment yield (SSY) associated with mass movements were collected from a fluviometric station, as well as maxima of these variables that were not associated with landslides. With these data, different General Linear Models were constructed considering possible non-linear effects of the covariates. Flow-type landslides triggered by rain (most of the events) are correctly predicted, especially using the linear effects of SSC and Q. For this mass movement type the prediction is suitable even for events triggered by isolated, short-lived rains, which are difficult to detect in mountainous areas with meteorological devices.