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Debris flow is an efficient process of sediment transfer from slope base to piedmont depositional fans in mountain drainage basins. To advance understanding of debris-flow sediment dynamics at the regional scale, we analyze a historical (1998-2009) database of debris flows from 77 basins of Alto Adige Province, northeastern Italy. By combining information on event volumetric deposition, high-resolution digital topography, and Quaternary sediment mapping we are able to link debris-flow sediment flux to morphometry, lithologic variability, and sediment availability. We show that basin-wide specific sediment yield (SSY) scales as an inverse power function of basin area. This function is strongly controlled by the way rock type and abundance of Quaternary deposits affect the rate of downstream sediment recruitment. When sediment flux associated with each debris-flow event is subsumed across discrete spatial increments of the entire region, a complex sedimentary signature in the area-SSY space is apparent. That is, SSY increases downstream up to areas as large as 1 km2, and starts to decline beyond this scale, regardless of sediment availability. We propose that this area-SSY relation is characteristic of debris flow-dominated settings.

Debris-flow monitoring in instrumented areas is an invaluable way to gather field data that may improve the understanding of these hazardous phenomena. A new experimental site has been equipped in the Autonomous Province of Bozen-Bolzano (Eastern Alps, Italy) for both monitoring purposes and testing early warning systems. The study site (Gadria basin) is a 6.3 km2 catchment subjected to frequent debris flows. The monitoring system in the Gadria basin consists of rain gauges, radar sensors, geophones, video cameras, piezometers and soil moisture probes. Transmission of data and alerts from the instruments exploits in part radio technology. The paper presents the data gathered during the first three years of activity, with two debris-flow events recorded at the station varying in magnitude and characteristics, and discusses the perspectives of debris-flow monitoring and related research. © 2014 Springer Science+Business Media Dordrecht.

Debris flows are one of the most relevant natural hazards in mountain regions. A combination of structural (e.g. check-dams) and non structural (e.g. warning systems) measures is needed in most cases to reduce debris flow risks, and both benefit from experimental data on debris-flow characteristics. A new experimental site is being equipped in the Autonomous Province of Bolzano (Italy) for both monitoring purposes and testing warning systems. The study site (Gadria basin) is a small channel subjected to frequent debris flows. The overall system includes the following components: 4 rain gauges located at different elevations, 5 radar sensors and 5 geophones, and 3 video cameras and flash lights to record the propagation and the deposition of the debris flow. Transmission of data and alerts from the instruments will use radio technology because GSM coverage is not available in the basin.

Debris flows are one of the most relevant natural hazards in mountain regions. A combination of structural (e.g. check-dams) and non structural (e.g. warning systems) measures is needed in most cases to reduce debris flow risks, and both benefit from experimental data on debris-flow characteristics. A new experimental site is being equipped in the Autonomous Province of Bolzano (Italy) for both monitoring purposes and testing warning systems. The study site (Gadria basin) is a small channel subjected to frequent debris flows. The overall system includes the following components: 4 rain gauges located at different elevations, 5 radar sensors and 5 geophones, and 3 video cameras and flash lights to record the propagation and the deposition of the debris flow. Transmission of data and alerts from the instruments will use radio technology because GSM coverage is not available in the basin.

Debris flows are one of the most relevant natural hazards in mountain regions. A combination of structural (e.g. check dams) and non structural (e.g. warning systems) measures is needed in most cases to reduce debris flow risks, and both benefit from experimental characteristics. A new experimental site is being equipped in the Autonomous Province of Bolzano (Italy) for both monitoring purposes and testing warning systems. The study site (Gadria basin) is a small channel subjected to frequent debris flows. The overall system includes the following components: 4 rain gauges located at different elevations, 5 radar sensors and 5 geophones, and 3 video cameras and flash lights to record the propagation and the deposition of the debris flow. Transmission of data and alerts from the instruments will use radio technology because GSM coverage is not available in the basin.

Debris flows are one of the most relevant natural hazards in mountain regions. A combination of structural (e.g. check dams) and non structural (e.g. warning systems) measures is needed in most cases to reduce debris flow risks, and both benefit from experimental characteristics. A new experimental site is being equipped in the Autonomous Province of Bolzano (Italy) for both monitoring purposes and testing warning systems. The study site (Gadria basin) is a small channel subjected to frequent debris flows. The overall system includes the following components: 4 rain gauges located at different elevations, 5 radar sensors and 5 geophones, and 3 video cameras and flash lights to record the propagation and the deposition of the debris flow. Transmission of data and alerts from the instruments will use radio technology because GSM coverage is not available in the basin.