Monitoring the propagation of a debris flow along a torrent

Abstract

The results are presented of a field experiment on debris flow monitoring that were obtained in the summer of 1996 in a small mountain torrent in the Italian Alps. A network of seismic detectors was placed about one kilometre upstream of some previously existing gauging stations equipped with ultrasonic devices. In June and July two debris flows occurred, whihc were recorded both by the seismic and the ultrasonic sensors allowing a comparison between the two results. For the first event, the plot of the mean velocity of ground vibration vs time revealed a strong similarity with the hydrograph recorded at the gauging sites: the graphs show the passage of a debris flow wave with a sharp peak followed by subsequent smaller waves. An estimation of the mean front velocity of these waves was performed at both sites.