Bergeron, Normand 
ORCID: https://orcid.org/0000-0003-2413-6810 et Carbonneau, Patrice E.
(1999).
The effect of sediment concentration on bedload roughness.
Hydrological Processes
, vol. 13
, nº 16.
pp. 2583-2589.
DOI: 10.1002/(SICI)1099-1085(199911)13:16<2583::AID-HYP939>3.0.CO;2-S.
Résumé
Bedload roughness is the roughness produced by sediment transported near the bed. While it is well established that the magnitude of this roughness is proportional to the thickness of the moving sediment layer, the effect of sediment concentration remains largely unknown. This paper presents the results of a flume experiment that was designed to investigate the effect of sediment concentration on bedload roughness. The experiment consisted of creating flow conditions where bedload transport is supply‐limited and injecting gravel size particles (D50=7·4 mm) at the upstream end of the flume in order to produce bedload transport. While keeping flow conditions constant, sediment concentration was varied by successively increasing the injection rate of gravel in the flow. For each injection rate, flow velocity profiles were measured in order to evaluate changes of mean flow velocity U, shear velocity u*, roughness length zo and resistance to flow f. The results indicate that low sediment concentration affects mainly the near bed portion of the flow where it causes a reduction of mean flow velocity and an increase of shear velocity and roughness length. For larger sediment concentration, the whole flow velocity profile becomes affected by bedload roughness but the importance of this effect always remain larger near the bed. As sediment concentration is augmented, mean flow velocity is consistently reduced but shear velocity and roughness length increase until a plateau is reached where these two variables become constant.
| Type de document: | Article |
|---|---|
| Mots-clés libres: | hydraulic; bedload roughness; sediment concentration; shear velocity; roughness length; resistance to flow |
| Centre: | Centre Eau Terre Environnement |
| Date de dépôt: | 03 févr. 2021 19:52 |
| Dernière modification: | 16 févr. 2022 20:21 |
| URI: | https://espace.inrs.ca/id/eprint/11144 |
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