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First direct measurements of hydraulic jumps in an active submarine density current

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
0094-8276
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
4124a194-0c22-40a7-b8ed-7664a0edc039
White, D.
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Sumner, E.J.
dbba4b92-89cc-45d9-888e-d0e87e5c10ac
Peakall, J.
2351dbf6-2c4f-4250-bacf-fe1b69870f26
Parsons, D.R.
8bc551f4-ae49-48cd-8533-82a34e749d74
Wynn, R.B.
72ccd765-9240-45f8-9951-4552b497475a
Darby, S.E.
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Dorrell, R.M.
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McPhail, S.D.
58ac4bcd-26a6-4845-8e81-6d6a8f18aed7
Perrett, J.
6392a5df-7574-4780-bb36-e5d4d3fd1d11
Webb, Andy
4124a194-0c22-40a7-b8ed-7664a0edc039
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), 5904-5908. (doi:10.1002/2013GL057862).

Record type: Article

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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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
ORCID for S.E. Darby: ORCID iD orcid.org/0000-0001-8778-4394

Catalogue record

Date deposited: 27 Nov 2013 10:08
Last modified: 08 Jan 2022 02:47

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Contributors

Author: E.J. Sumner
Author: J. Peakall
Author: D.R. Parsons
Author: R.B. Wynn
Author: S.E. Darby ORCID iD
Author: R.M. Dorrell
Author: S.D. McPhail
Author: J. Perrett
Author: Andy Webb
Author: D. White

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