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Accueil > Actualités > Séminaires > Séminaires 2022

Mardi 24 Mai 11h00 - LEGI Salle K118

Celine Berni, INRAE Lyon

Title : Suspended sediment deposits over floodplain : insight from experimental studies

Contact : Marie Rastello

Abstract : Fines sediments represent a significant issue in Alpine rivers since it can raise both physical and ecological impacts. Indeed, large sedimentation in reservoir affects hydro-power dam efficiency ; also clogging and deposits overs a gravel matrix reduce the habitat quality. We think that fine sediment dynamics over gravel bars can be studied through laboratory experiments in a compound cross-section. We explored sediment-laden flows as well as clear water flows for two different discharges. The comparison of two test cases with the same flow rate Q, one with clear water, the other with fine sediments, firstly enabled to assess the main factors controlling the transfer and deposits of fine sediments of : (i) the time-averaged transverse flow (from MC to FP) ; and (ii) quasi-two-dimensional CSs that form at the interfacial region between MC and FP. The second aim of the study was to analyze the retroactive effects of sediment deposition on the hydrodynamics of overbank flows. We analyzed, in particular, the effects of the deposits on the stream-wise changes in water level, on the span-wise profiles of the time-averaged velocity and turbulence statistics, and on the stream-wise and span-wise length-scales of the CSs. The results show there is an interaction between fine sediment dynamics and flow characteristics.

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