Journal cover Journal topic
Hydrology and Earth System Sciences An interactive open-access journal of the European Geosciences Union
Hydrol. Earth Syst. Sci., 19, 3991-4000, 2015
https://doi.org/10.5194/hess-19-3991-2015
© Author(s) 2015. This work is distributed under
the Creative Commons Attribution 3.0 License.
Technical note
25 Sep 2015
Technical Note: The use of an interrupted-flow centrifugation method to characterise preferential flow in low permeability media
R. A. Crane1,2, M. O. Cuthbert2,3, and W. Timms2,4 1School of Civil and Environmental Engineering, UNSW, Sydney, Australia
2Connected Waters Initiative Research Centre, UNSW, Sydney, Australia
3School of Geography, Earth and Environmental Sciences, University of Birmingham, Birmingham, UK
4School of Mining Engineering, UNSW, Sydney, Australia
Abstract. 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.

Citation: Crane, R. A., Cuthbert, M. O., and Timms, W.: Technical Note: The use of an interrupted-flow centrifugation method to characterise preferential flow in low permeability media, Hydrol. Earth Syst. Sci., 19, 3991-4000, https://doi.org/10.5194/hess-19-3991-2015, 2015.
Publications Copernicus
Download
Short summary
We present an interrupted-flow centrifugation technique to characterise the vertical hydraulic properties of dual porosity, low permeability media. Use of large core samples (100mm diameter) enables hydraulic-conductivity-scale issues in dual porosity media to be overcome. Elevated centrifugal force also enables simulating in situ total stress conditions. The methodology is an important tool to assess the ability of dual porosity aquitards to protect underlying aquifer systems.
We present an interrupted-flow centrifugation technique to characterise the vertical hydraulic...
Share