Wind and buoyancy driven horizontal exchange in shallow embayments of a tropical reservoir: Lake Argyle, Western Australia

© 2017 Association for the Sciences of Limnology and Oceanography Many factors including depth, vegetation density, wind, and gyres may act to influence the littoral exchange in a water body but very few studies have investigated the interaction between more than two of these factors at any time. To...

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Main Authors: Woodward, B., Marti, Clelia, Imberger, J., Hipsey, M., Oldham, C.
Format: Journal Article
Published: American Society of Limnology and Oceanography, Inc. 2017
Online Access:http://hdl.handle.net/20.500.11937/65560
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author Woodward, B.
Marti, Clelia
Imberger, J.
Hipsey, M.
Oldham, C.
author_facet Woodward, B.
Marti, Clelia
Imberger, J.
Hipsey, M.
Oldham, C.
author_sort Woodward, B.
building Curtin Institutional Repository
collection Online Access
description © 2017 Association for the Sciences of Limnology and Oceanography Many factors including depth, vegetation density, wind, and gyres may act to influence the littoral exchange in a water body but very few studies have investigated the interaction between more than two of these factors at any time. To investigate these controls on horizontal exchange in a large tropical reservoir, we conducted a 9-d intensive field experiment in Lake Argyle, Western Australia. The experiment began with a 7-d cooling period that generated water in the shallows of the reservoir embayments that was persistently cooler than the interior. This led to an underflow of dense water that moved from the lake boundary toward the center of the reservoir. A three-dimensional hydrodynamic model (ELCOM) was able to adequately reproduce this thermal structure and was used to demonstrate its sensitivity to wind-sheltering effects and submerged macrophyte presence. Further analysis of the predictions indicated that when the ratio of the shear and buoyancy force, averaged over 6 h (B 6h ) and 6-h averaged wind speed in the direction of the embayment (U 6h ) was (1) greater than 0.5 ms -1 and 4.5 ms -1 respectively, the exchange was dominated by a topographic gyre formation, (2) when 0.1 < B 6h < 0.5 and 2.4 ms -1 < U 6h < 4.5 ms -1 , the resulting circulation was a combination of differential cooling flows and a topographic gyre circulation, and (3) when U 6h fell below 2.4 ms -1 , purely buoyancy driven flow occurred but only if the buoyancy forces across the embayments were an order of magnitude greater than wind-induced velocity shear.
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spelling curtin-20.500.11937-655602018-02-19T08:06:42Z Wind and buoyancy driven horizontal exchange in shallow embayments of a tropical reservoir: Lake Argyle, Western Australia Woodward, B. Marti, Clelia Imberger, J. Hipsey, M. Oldham, C. © 2017 Association for the Sciences of Limnology and Oceanography Many factors including depth, vegetation density, wind, and gyres may act to influence the littoral exchange in a water body but very few studies have investigated the interaction between more than two of these factors at any time. To investigate these controls on horizontal exchange in a large tropical reservoir, we conducted a 9-d intensive field experiment in Lake Argyle, Western Australia. The experiment began with a 7-d cooling period that generated water in the shallows of the reservoir embayments that was persistently cooler than the interior. This led to an underflow of dense water that moved from the lake boundary toward the center of the reservoir. A three-dimensional hydrodynamic model (ELCOM) was able to adequately reproduce this thermal structure and was used to demonstrate its sensitivity to wind-sheltering effects and submerged macrophyte presence. Further analysis of the predictions indicated that when the ratio of the shear and buoyancy force, averaged over 6 h (B 6h ) and 6-h averaged wind speed in the direction of the embayment (U 6h ) was (1) greater than 0.5 ms -1 and 4.5 ms -1 respectively, the exchange was dominated by a topographic gyre formation, (2) when 0.1 < B 6h < 0.5 and 2.4 ms -1 < U 6h < 4.5 ms -1 , the resulting circulation was a combination of differential cooling flows and a topographic gyre circulation, and (3) when U 6h fell below 2.4 ms -1 , purely buoyancy driven flow occurred but only if the buoyancy forces across the embayments were an order of magnitude greater than wind-induced velocity shear. 2017 Journal Article http://hdl.handle.net/20.500.11937/65560 10.1002/lno.10522 American Society of Limnology and Oceanography, Inc. restricted
spellingShingle Woodward, B.
Marti, Clelia
Imberger, J.
Hipsey, M.
Oldham, C.
Wind and buoyancy driven horizontal exchange in shallow embayments of a tropical reservoir: Lake Argyle, Western Australia
title Wind and buoyancy driven horizontal exchange in shallow embayments of a tropical reservoir: Lake Argyle, Western Australia
title_full Wind and buoyancy driven horizontal exchange in shallow embayments of a tropical reservoir: Lake Argyle, Western Australia
title_fullStr Wind and buoyancy driven horizontal exchange in shallow embayments of a tropical reservoir: Lake Argyle, Western Australia
title_full_unstemmed Wind and buoyancy driven horizontal exchange in shallow embayments of a tropical reservoir: Lake Argyle, Western Australia
title_short Wind and buoyancy driven horizontal exchange in shallow embayments of a tropical reservoir: Lake Argyle, Western Australia
title_sort wind and buoyancy driven horizontal exchange in shallow embayments of a tropical reservoir: lake argyle, western australia
url http://hdl.handle.net/20.500.11937/65560