Debris-flow data collected in the Moscardo Torrent (eastern Italian Alps) between 1990 and 2019

Abstract

<p>Debris-flow research requires experimental data that are difficult to collect because of the intrinsic characteristics of these processes. Both post-event field observations and monitoring in instrumented channels are suitable to collect debris-flow field data, even if with different resolutions and purposes. Monitoring in instrumented channels enables recording data that cannot be gathered by means of post-event surveys in ungauged channels. Extending the monitoring activities over multidecadal time intervals increases the significance of collected data because longer time series permit recognizing changes in debris-flow response as a consequence of changes in controlling factors, such as climate, land use, and the implementation of control works.</p><p>This paper presents debris-flows data recorded in the Moscardo Torrent (eastern Italian Alps) between 1990 and 2019. As far as we know, the Moscardo Torrent basin was the first catchment equipped with permanent instrumentation for debris-flow monitoring in Europe. The monitoring activities in the Moscardo Torrent began in 1989-1990 and still keep on, although with some gaps due to the implementation of control works in the instrumented channel (1998-2000) and the obsolescence of the instrumentation between 2007 and 2010.</p><p>Thirty debris flows were observed between 1990 and 2019; 26 of them were monitored by sensors installed on the channel (at two measuring stations for most events), while four debris flows were documented by means of post-event observations. Monitored data consist of debris-flow hydrographs, measured by means of ultrasonic sensors, and rainfall. Debris flows in the Moscardo Torrent occur from early June to the end of September, with higher frequency in the first part of summer.</p><p>This contribution presents data on triggering rainfall, flow velocity, peak discharge and volume for the monitored hydrographs. The relatively large number of debris-flow events recorded in the Moscardo Torrent has permitted to recognize the main characteristics of the debris-flow hydrographs. We used the data related to duration and the maximum depth of the debris-flow surges to define triangular hydrographs related to different event severity. Simplified triangular hydrographs show the distinctive features of debris flows (short total event duration and very short time to peak) and can help defining realistic inputs to debris-flow propagation models. A more detailed representation of hydrographs shape was achieved by averaging the recorded hydrographs of debris-flow surges. This analysis was performed on the debris flows recorded between 2002 and 2019: data for 12 surges for each of the two flow measuring stations were available. Dimensionless hydrographs were generated normalizing the flow depth by its maximum value and the time by the total surge duration. Flow peaks were aligned to preserve the sharp shape that is a distinctive feature of debris-flow hydrographs. Finally, the ordinates were averaged, and mean debris-flow hydrographs were obtained.</p><p>Debris-flow data collected in the Moscardo Torrent dataset could contribute to further analysis, including the comparison of triggering rainfall and flow variables with those recorded in other basins instrumented for debris-flows monitoring under different climate and geolithological conditions.</p>