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Proceedings/Recueil Des Communications Proceedings of the 39th IAHR World Congress Année : 2023

Experimental Study on Suspended Sediment Deposits over Floodplains

Étude expérimentale de dépôts de sédiments fins sur les plaines d'inondation

Céline Berni
S. Proust
B. Camenen

Résumé

Fines sediments represent a significant issue in piedmont and lowland rivers since their deposits can raise both physical and ecological impacts. The objective of this work is to better understand fine sediment dynamics over gravel bars based on laboratory experiments. Open-channel flows were investigated in a laboratory flume with an asymmetrical compound cross-section, i.e. including a Main Channel (MC) and one adjacent Flood Plain (FP) simulating a gravel bar. At the flume entrance, the total flow rate was injected in the MC. As this flow rate exceeds the inbank discharge in the MC, a transverse flow occurs from MC to FP. First, water level profiles and flow structure (time-averaged velocity, turbulence statistics) were studied for a clear water case. Second, similar experiments were conducted with water loaded with fine sediments, so that transfer and deposits of fine sediments over the FP could be observed. The comparison of clear water and fine sediment-laden flows enabled to assess the main factors controlling the fine sediments dynamics: (i) the magnitude and direction of the time-averaged transverse flow between MC and FP; and (ii) the quasi-twodimensional coherent structures that form at the interfacial region between MC and FP. We also analyzed the retroactive effects of sediment deposition on the hydrodynamics of overbank flows such as the streamwise changes in water level, and the spanwise profiles of the time-averaged velocity and turbulence statistics. The results show there is an interaction between fine sediment dynamics and flow characteristics.
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Dates et versions

hal-04347199 , version 1 (15-12-2023)

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Lorenzo Boisson, Céline Berni, S. Proust, B. Camenen. Experimental Study on Suspended Sediment Deposits over Floodplains. 39th IAHR World Congress, Proceedings of the 39th IAHR World Congress, pp.459-463, 2023, ⟨10.3850/IAHR-39WC2521716X2022703⟩. ⟨hal-04347199⟩
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