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| Titel |
Technical Note: The use of an interrupted-flow centrifugation method to characterise preferential flow in low permeability media |
| VerfasserIn |
R. A. Crane, M. O. Cuthbert, W. Timms |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1027-5606
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| Digitales Dokument |
URL |
| Erschienen |
In: Hydrology and Earth System Sciences ; 19, no. 9 ; Nr. 19, no. 9 (2015-09-25), S.3991-4000 |
| Datensatznummer |
250120815
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| Publikation (Nr.) |
 copernicus.org/hess-19-3991-2015.pdf |
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| Zusammenfassung |
| We present an interrupted-flow centrifugation technique to characterise
preferential flow in low permeability media. The method entails a minimum of
three phases: centrifuge-induced flow, no flow and centrifuge-induced flow,
which may be repeated several times in order to most effectively characterise
multi-rate mass transfer behaviour. In addition, the method enables accurate
simulation of relevant in situ total stress conditions during flow by
selecting an appropriate centrifugal force. We demonstrate the utility of the
technique for characterising the hydraulic properties of smectite-clay-dominated core samples. All core samples exhibited a non-Fickian tracer
breakthrough (early tracer arrival), combined with a decrease in tracer
concentration immediately after each period of interrupted flow. This is
indicative of dual (or multi-)porosity behaviour, with solute migration
predominately via advection during induced flow, and via molecular diffusion
(between the preferential flow network(s) and the low hydraulic conductivity
domain) during interrupted flow. Tracer breakthrough curves were simulated
using a bespoke dual porosity model with excellent agreement between the data
and model output (Nash–Sutcliffe model efficiency coefficient was > 0.97
for all samples). In combination, interrupted-flow centrifuge experiments and
dual porosity transport modelling are shown to be a powerful method to
characterise preferential flow in low permeability media. |
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