Author(s): Stancanelli Laura Maria; Lanzoni Stefano; Foti Enrico
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Keywords: Debris flow; Confluence angle; Slope; Triggering dynamics
Abstract: The interaction between debris flows generated in two contiguous tributaries which propagate and deposit in the same main river reach has been investigated experimentally. In particular, the aim of the present experimental research has been to analyze the geometry of debris flow deposits conveyed by two lateral tributaries in a main channel reach, considering the influence of different parameters such as: the slope, the confluence angle and the difference of debris flow triggering time. The experimental set up includes a main channel reach and two lateral channels located on its left side. Six different acoustic level sensors and four pressure transducers have been installed along the experiment apparatus in order to monitor flow levels and pressures during the propagation and the deposition of the debris flows. A set of 19 experiments has been conducted by considering three values of the confluence angle (90°-60°-45°), two slopes of the tributary channels (15° e 17°), and three different triggering conditions (i. e., debris flows occurring simultaneously in the tributaries, or occurring first either in the upstream or in the downstream tributary), while the flow rate along the main channel has been kept constant. During each experiment the same slope and confluence angle have been set for both the lateral tributaries. The data analysis indicates that the interaction between the debris flow deposits settled along the main river reach is maxim for debris flows generated simultaneously in the two tributaries at higher slope (i. e., 17°) and for a confluence angle of 90°.
Year: 2013