Physical modelling of debris flow deposits in contiguous confluences

Dam formation in river channel generated by single and multiple debris flow injections from affluent basins are investigated in through flume experiments. The aim of the research is to understand the morphodynamics that governs the dam formation. A set of 14 experiments considering both single and double debris flow injections have been carried out, investigating different configurations in terms of debris flow discharge, confluence angle and water discharge along the main channel. In all cases, the debris flow consisted of a mixture of gravel and water, that reproduces stony-debris flow conditions. Results from single confluence experiments are taken as reference for better understanding the interactions between the different deposits when considering adjacent debris flow injections. The collected data are used to test the critical indexes for dam formation probability proposed in literature.