Data of Rainfall-runoff modelling in rocky headwater catchments for the prediction of debris flow occurrence

In the Dolomites area, sub-vertical rocky cliffs are incised by several chutes, which concentrate runoff and deliver it to the scree at the base of the cliffs, where the erosive activity of surface discharges creates debris-flow channels. Following high-intensity short-duration precipitations, the abundant runoff entrains a large quantity of loose debris material forming a solid-liquid surge. Along the channel, the flowing surge entrains boulders, gravel, and sand becoming an increasingly larger stony debris flow. For studying the hydrological response of headwater rocky catchments and the initiation of stony debris flows, we take advantage of data recorded by three monitoring stations, which operated in distinct debris flow catchments. All of them are located in the initiation area of the basins and record videos and different types of flow-stage data, which allow us to identify the timing and shape of the incoming flow. During the 15-year monitoring period, a large number of observations of runoff and mass-transport phenomena were recorded. This dataset forms a unique collection of data for analyzing the hydrological response of small and steep headwater basins, as well as for studying the initiation of stony debris flows. An existing hydrological model has been partially reformulated, and its updated version was calibrated using the hydrographs measured by a sharp-crested weir. We tested the updated model against the observations recorded in two larger debris flow catchments. The comparison confirms that the proposed model is capable of reproducing the initial stages of a debris flow when the sediment concentration rapidly increases.