Modelling the equilibrium bed topography of submarine meanders that exhibit reversed secondary flows
Modelling the equilibrium bed topography of submarine meanders that exhibit reversed secondary flows
Submarine meandering channels formed by turbidity currents are common; however, their location on the ocean floor and their inactive status make it difficult to measure process dynamics and bed morphology. Conceptual models have, therefore, instead been developed by analogy with the well understood mechanics of fluvial bends. However, unlike fluvial currents, in turbidity currents the downstream velocity maximum typically occurs near the bed and recent experimental and theoretical studies suggest that, under certain hydraulic and morphological conditions, this forces the secondary flow to exhibit the reverse sense to that encountered in fluvial bends. Herein the possible morphological implications of a reversal of secondary flow are explored by modelling the force balance on sediment grains moving through either (i) field and laboratory submarine meander bends that are known to exhibit ‘reversed’ secondary flows, or (ii) inactive submarine meander bends where the nature of the secondary flow in the formative turbidity currents can be inferred to be reversed. Exploratory simulations are undertaken for a single hypothetical submarine bend with morphological properties based on nine relic meanders observed on the floor of the Gulf of Alaska. Reconstructions of secondary flow properties within the Gulf of Alaska bends indicate that they likely exhibited reversed secondary flows. Results of the exploratory simulations indicate that, unlike typical fluvial meanders, the transverse bed profile gradient of the hypothetical bend is very low and the point bar is located downstream of the bend apex
submarine channel, bends, meanders, bed topography, turbidity currents, helical flow
99-109
Darby, Stephen E.
4c3e1c76-d404-4ff3-86f8-84e42fbb7970
Peakall, Jeffrey
9bbaf650-71db-495c-9f01-19918cd2c81b
15 August 2012
Darby, Stephen E.
4c3e1c76-d404-4ff3-86f8-84e42fbb7970
Peakall, Jeffrey
9bbaf650-71db-495c-9f01-19918cd2c81b
Darby, Stephen E. and Peakall, Jeffrey
(2012)
Modelling the equilibrium bed topography of submarine meanders that exhibit reversed secondary flows.
Geomorphology, 163-164, .
(doi:10.1016/j.geomorph.2011.04.050).
Abstract
Submarine meandering channels formed by turbidity currents are common; however, their location on the ocean floor and their inactive status make it difficult to measure process dynamics and bed morphology. Conceptual models have, therefore, instead been developed by analogy with the well understood mechanics of fluvial bends. However, unlike fluvial currents, in turbidity currents the downstream velocity maximum typically occurs near the bed and recent experimental and theoretical studies suggest that, under certain hydraulic and morphological conditions, this forces the secondary flow to exhibit the reverse sense to that encountered in fluvial bends. Herein the possible morphological implications of a reversal of secondary flow are explored by modelling the force balance on sediment grains moving through either (i) field and laboratory submarine meander bends that are known to exhibit ‘reversed’ secondary flows, or (ii) inactive submarine meander bends where the nature of the secondary flow in the formative turbidity currents can be inferred to be reversed. Exploratory simulations are undertaken for a single hypothetical submarine bend with morphological properties based on nine relic meanders observed on the floor of the Gulf of Alaska. Reconstructions of secondary flow properties within the Gulf of Alaska bends indicate that they likely exhibited reversed secondary flows. Results of the exploratory simulations indicate that, unlike typical fluvial meanders, the transverse bed profile gradient of the hypothetical bend is very low and the point bar is located downstream of the bend apex
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Published date: 15 August 2012
Keywords:
submarine channel, bends, meanders, bed topography, turbidity currents, helical flow
Organisations:
Earth Surface Dynamics
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Local EPrints ID: 200917
URI: http://eprints.soton.ac.uk/id/eprint/200917
ISSN: 0169-555X
PURE UUID: ed9a019d-99c0-41ad-99a7-41c36e0cbb71
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Date deposited: 28 Oct 2011 08:12
Last modified: 15 Mar 2024 02:58
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Author:
Jeffrey Peakall
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