Flow patterns, sedimentation and deposit architecture under a hydraulic jump on a non-eroding bed: Defining hydraulic-jump unit bars

MacDonald, Robert G, Alexander, Jan, Bacon, John C and Cooker, Mark J (2009) Flow patterns, sedimentation and deposit architecture under a hydraulic jump on a non-eroding bed: Defining hydraulic-jump unit bars. Sedimentology, 56 (5). pp. 1346-1367. ISSN 1365-3091

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Abstract

This paper presents results from two flume runs of an ongoing series examining flow structure, sediment transport and deposition in hydraulic jumps. It concludes in the presentation of a model for the development of sedimentary architecture, considered characteristic of a hydraulic jump over a non-eroding bed. In Run 1, a hydraulic jump was formed in sediment-free water over the solid plane sloping flume floor. Ultrasonic Doppler velocity profilers recorded the flow structure within the hydraulic jump in fine detail. Run 2 had identical initial flow conditions and a near-steady addition of sand, which formed beds with two distinct characteristics: a laterally extensive, basal, wedge-shaped massive sand bed overlain by cross-laminated sand beds. Each cross-laminated bed recorded the initiation and growth of a single surface feature, here defined as a hydraulic-jump unit bar. A small massive sand mound formed on the flume floor and grew upstream and downstream without migrating to form a unit bar. In the upstream portion of the unit bar, sand finer than the bulk load formed a set of laminae dipping upstream. This set passed downstream through the small volume of massive sand into a foreset, which was initially relatively coarse-grained and became finer-grained downstream. This downstream-fining coincided with cessation of the growth of the upstream-dipping cross-set. At intervals, a new bed feature developed above and upstream of the preceding hydraulic-jump unit bar and grew in the same way, with the foreset climbing the older unit bar. The composite architecture of the superimposed unit bars formed a fanning, climbing coset above the massive wedge, defined as one unit: a hydraulic-jump bar complex.

Item Type: Article
Faculty \ School: Faculty of Science > School of Environmental Sciences
Faculty of Science > School of Mathematics
Related URLs:
Depositing User: Rosie Cullington
Date Deposited: 23 Feb 2011 10:37
Last Modified: 21 Apr 2020 17:41
URI: https://ueaeprints.uea.ac.uk/id/eprint/24378
DOI: 10.1111/j.1365-3091.2008.01037.x

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