Ten years of debris-flow monitoring in the Moscardo Torrent (Italian Alps)

Abstract

Field data on debris flows are of utmost importance for improving knowledge of these hazardous phenomena and for the development of attenuation measures. In alpine basins, debris flows generally occur with a frequency high enough to create serious risk to human settlements and transportation routes, but too low to justify monitoring activity capable of providing enough data in a sufficiently short time. The Moscardo Torrent, a small stream in the Eastern Italian Alps, is an exception to this general situation since it displays a high frequency of debris flows (commonly at least one event per year). In 1989, this torrent was instrumented and the results of the following 10 years (1989–1998) of debris-flow monitoring are presented, with an analysis of collected data. The equipment installed allowed measurement of rainfall, flow stage and ground vibrations caused by debris flows. Other important debris-flow variables, that is, mean front velocity, peak discharge and flowing volume were estimated from instrumental records. Video pictures have proved to be useful for the visual interpretation of debris-flow waves and have made it possible to estimate the surface velocity of debris flows. Recorded data are compared with other experimental data sets collected and documented worldwide. Advantages and shortcomings of different types of sensors are discussed with relevance both for research monitoring purposes and for possible use in debris-flow warning systems.