Transport of nonsorbing solutes in a streambed with periodic bedforms

Jin, GQ, Tang, HW, Gibbes, B, Li, L and Barry, DA (2010) Transport of nonsorbing solutes in a streambed with periodic bedforms. Advances in Water Resources, 33 11: 1402-1416. doi:10.1016/j.advwatres.2010.09.003


Author Jin, GQ
Tang, HW
Gibbes, B
Li, L
Barry, DA
Title Transport of nonsorbing solutes in a streambed with periodic bedforms
Journal name Advances in Water Resources   Check publisher's open access policy
ISSN 0309-1708
1872-9657
Publication date 2010-11-01
Year available 2010
Sub-type Article (original research)
DOI 10.1016/j.advwatres.2010.09.003
Open Access Status Not yet assessed
Volume 33
Issue 11
Start page 1402
End page 1416
Total pages 15
Place of publication Oxford, United Kingdom
Publisher Pergamon
Language eng
Abstract Previous studies of hyporheic zone focused largely on the net mass transfer of solutes between stream and streambed. Solute transport within the bed has attracted less attention. In this study, we combined flume experiments and numerical simulations to examine solute transport processes in a streambed with periodic bedforms. Solute originating from the stream was subjected to advective transport driven by pore water circulation due to current-bedform interactions as well as hydrodynamic dispersion in the porous bed. The experimental and numerical results showed that advection played a dominant role at the early stage of solute transport, which took place in the hyporheic zone. Downward solute transfer to the deep ambient flow zone was controlled by transverse dispersion at the later stage when the elapsed time exceeded the advective transport characteristic time t(c) (= L/u(c) with L being the bedform length and u(c) the characteristic pore water velocity). The advection-based pumping exchange model was found to predict reasonably well solute transfer between the overlying water and streambed at the early stage but its performance deteriorated at the later stage. With dispersion neglected, the pumping exchange model underestimated the long-term rate and total mass of solute transfer from the overlying water to the bed. Therefore both advective and dispersive transport components are essential for quantification of hyporheic exchange processes. (C) 2010 Elsevier Ltd. All rights reserved.
Formatted abstract
Previous studies of hyporheic zone focused largely on the net mass transfer of solutes between stream and streambed. Solute transport within the bed has attracted less attention. In this study, we combined flume experiments and numerical simulations to examine solute transport processes in a streambed with periodic bedforms. Solute originating from the stream was subjected to advective transport driven by pore water circulation due to current-bedform interactions as well as hydrodynamic dispersion in the porous bed. The experimental and numerical results showed that advection played a dominant role at the early stage of solute transport, which took place in the hyporheic zone. Downward solute transfer to the deep ambient flow zone was controlled by transverse dispersion at the later stage when the elapsed time exceeded the advective transport characteristic time tc (= L/uc with L being the bedform length and uc the characteristic pore water velocity). The advection-based pumping exchange model was found to predict reasonably well solute transfer between the overlying water and streambed at the early stage but its performance deteriorated at the later stage. With dispersion neglected, the pumping exchange model underestimated the long-term rate and total mass of solute transfer from the overlying water to the bed. Therefore both advective and dispersive transport components are essential for quantification of hyporheic exchange processes.
© 2010 Elsevier Ltd.
Keyword Solute transport
Bedform
Advection
Dispersion
Q-Index Code C1
Q-Index Status Confirmed Code
Grant ID 50425926
2009422211
2009809514
DP0988718
Institutional Status UQ
Additional Notes Special Issue on ground water-surface water interactions - GW-SW Interactions. Edited by Jan H. Fleckenstein, Stefan Krause, David M. Hannah and Fulvio Boano.

Document type: Journal Article
Sub-type: Article (original research)
Collections: School of Civil Engineering Publications
Official 2011 Collection
 
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Created: Sun, 20 Feb 2011, 10:07:51 EST