Debris flows sediment volume in hyper-arid mountain catchments

Intense rainfall in hyper-arid mountain catchments usually triggers debris flows that can transport large volumes of sediment. Determining the debris flow volume is critical for developing strategies to manage and control debris flow hazards in mountain environments. This work estimates the sediment volumes available in the catchments and compares them with the transport capacity of these catchments. Both volumes are contrasted with field observations of past events in the Atacama Desert. The thickness of sediment stored in channels and hillslopes is estimated based on field observations, linking them to the channel width and the slope of the hillslopes, respectively. The transportable volume is calculated considering a design rainfall with a return time of 100 years, the contributing area of the catchments, a runoff coefficient, and the equilibrium concentration that is a function of the slope of the catchments. The results indicate that 40% of the sediment available in channels and 6% available on slopes represents the transportable volume for the design rainfall.