Coupling acoustic devices to monitor combined sewer networks sediment deposits
Résumé
Combined sewer networks present unique features that are not well reproduced in laboratory conditions and yet far to be understood. The transport of organic and mobile sediments, present in large quantities despite the optimal design of the channel, dramatically changes the structure of the deposits. Hence, to understand flow patterns and transport features of these complex environments, it is necessary to install in-situ instrumentation. In this paper, two different acoustic techniques are coupled to measure both the sediment interface and the velocity. In this case, a 2 MHz rotating head acoustic profiler and a10 MHz Acoustic Doppler Velocimeter (ADV) have been installed together to survey both the position of the sediments deposit and to measure velocity patterns. The results will compare measurements obtained in different environments in which both coarser and finer and softer deposits are present. The results generally show a good agreement between the interfaces detected using the velocity measurements on coarse deposits, while the presence of different type soft deposit highlights the necessity of coupling measurements techniques that correctly asses the sediment interface.