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Flow patterns, sedimentation and deposit architecture under a hydraulic jump on a non-eroding bed: defining hydraulic-jump unit bars.
- Source :
-
Sedimentology . Aug2009, Vol. 56 Issue 5, p1346-1367. 22p. 2 Color Photographs, 8 Diagrams, 3 Graphs. - Publication Year :
- 2009
-
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. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 00370746
- Volume :
- 56
- Issue :
- 5
- Database :
- Academic Search Index
- Journal :
- Sedimentology
- Publication Type :
- Academic Journal
- Accession number :
- 45277134
- Full Text :
- https://doi.org/10.1111/j.1365-3091.2008.01037.x