First direct measurements of hydraulic jumps in an active submarine density current
First direct measurements of hydraulic jumps in an active submarine density current
For almost half a century, it has been suspected that hydraulic jumps, which consist of a sudden decrease in downstream velocity and increase in flow thickness, are an important feature of submarine density currents such as turbidity currents and debris flows. Hydraulic jumps are implicated in major seafloor processes, including changes from channel erosion to fan deposition, flow transformations from debris flow to turbidity current, and large-scale seafloor scouring. We provide the first direct evidence of hydraulic jumps in a submarine density current and show that the observed hydraulic jumps are in phase with seafloor scours. Our measurements reveal strong vertical velocities across the jumps and smaller than predicted decreases in downstream velocity. Thus, we demonstrate that hydraulic jumps need not cause instantaneous and catastrophic deposition from the flow as previously suspected. Furthermore, our unique data set highlights problems in using depth-averaged velocities to calculate densimetric Froude numbers for gravity currents.
hydraulic jump, density current, froude number, black sea, ADCP
5904-5908
Sumner, E.J.
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Peakall, J.
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Parsons, D.R.
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Wynn, R.B.
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Darby, S.E.
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Dorrell, R.M.
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McPhail, S.D.
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Perrett, J.
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Webb, Andy
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White, D.
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28 November 2013
Sumner, E.J.
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Peakall, J.
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Parsons, D.R.
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Wynn, R.B.
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Darby, S.E.
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Dorrell, R.M.
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McPhail, S.D.
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Perrett, J.
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Webb, Andy
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White, D.
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Sumner, E.J., Peakall, J., Parsons, D.R., Wynn, R.B., Darby, S.E., Dorrell, R.M., McPhail, S.D., Perrett, J., Webb, Andy and White, D.
(2013)
First direct measurements of hydraulic jumps in an active submarine density current.
Geophysical Research Letters, 40 (22), .
(doi:10.1002/2013GL057862).
Abstract
For almost half a century, it has been suspected that hydraulic jumps, which consist of a sudden decrease in downstream velocity and increase in flow thickness, are an important feature of submarine density currents such as turbidity currents and debris flows. Hydraulic jumps are implicated in major seafloor processes, including changes from channel erosion to fan deposition, flow transformations from debris flow to turbidity current, and large-scale seafloor scouring. We provide the first direct evidence of hydraulic jumps in a submarine density current and show that the observed hydraulic jumps are in phase with seafloor scours. Our measurements reveal strong vertical velocities across the jumps and smaller than predicted decreases in downstream velocity. Thus, we demonstrate that hydraulic jumps need not cause instantaneous and catastrophic deposition from the flow as previously suspected. Furthermore, our unique data set highlights problems in using depth-averaged velocities to calculate densimetric Froude numbers for gravity currents.
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grl51104_Sumner.pdf
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More information
e-pub ahead of print date: 19 November 2013
Published date: 28 November 2013
Keywords:
hydraulic jump, density current, froude number, black sea, ADCP
Organisations:
Ocean and Earth Science, Geology & Geophysics, Marine Geoscience, National Oceanography Centre, Ocean Technology and Engineering
Identifiers
Local EPrints ID: 360130
URI: http://eprints.soton.ac.uk/id/eprint/360130
ISSN: 0094-8276
PURE UUID: 942fc350-83d8-46b0-8df1-5333feb10015
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Date deposited: 27 Nov 2013 10:08
Last modified: 15 Mar 2024 02:58
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Contributors
Author:
J. Peakall
Author:
D.R. Parsons
Author:
R.B. Wynn
Author:
R.M. Dorrell
Author:
S.D. McPhail
Author:
J. Perrett
Author:
Andy Webb
Author:
D. White
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