Stony Debris Flow Debouching in a River Reach: Energy Dissipative Mechanisms and Deposit Morphology
Stony debris flows are investigated at the laboratory scale. A set of 11 experiments are carried out, to simulate the stony debris flow propagation in a typical mountain confluence with a downstream water channel. The dynamic of the tributary flow just upstream of the junction with the river, surrogated through the volumetric mixture discharge, is assessed through the analysis of velocity profiles, while observations on deposit morphology provide insight into the condition which cause the blockage of the main stream. Energy dissipation within the solid–liquid mixture is mainly controlled by collisions between grains, and a dilatant fluid model is found to approximately reproduce the velocity profile. The degree of river blockage caused by the delivered material is classified according to three configurations: (i) full blockage, whereby the entire transversal river section is dammed (100% river obstruction); (ii) no blockage when less than 60% of the transversal river section is interested by the deposit; (iii) partial blockage for intermediate damming configurations (>60% and <100% of the river obstruction).
KeywordsStony debris flow Confluence Velocity profile River damming
The authors would like to thank Enrica Belluco from the Hydraulic Laboratory of the University of Padova for help with the experimental development and Rosaria Musumeci from the Department of Civil Engineering and Architecture of the University of Catania for insightful discussions. Thanks also to prof. Carlo Gregoretti who provides us the field image of stony debris flow channel acquired in Fiames, Cortina d’Ampezzo (Italian Dolomites). This work has been partly funded by the EU funded project HYDRALAB PLUS (proposal number 654110) and—financed by MIUR within PON R&C 2007–2013 Research Project “CLARA—CLoud platform and smart underground imaging for natural Risk Assessment”.
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