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WATER RESOURCES RESEARCH, VOL. 41, W11504, doi:10.1029/2005WR003957, 2005

Quasi-steady centrifuge method for unsaturated hydraulic properties

Maria C. Caputo

Water Research Institute (IRSA), Consiglio Nazionale delle Ricerche, Bari, Italy


John R. Nimmo

U.S. Geological Survey, Menlo Park, California, USA


Abstract

We have developed the quasi-steady centrifuge (QSC) method as a variation of the steady state centrifuge method that can be implemented simply and inexpensively with greater versatility in terms of sample size and other features. It achieves these advantages by somewhat relaxing the criterion for steadiness of flow through the sample. This compromise entails an increase in measurement uncertainty but to a degree that is tolerable in most applications. We have tested this new approach with an easily constructed apparatus to establish a quasi-steady flow of water in unsaturated porous rock samples spinning in a centrifuge, obtaining measurements of unsaturated hydraulic conductivity and water retention that agree with results of other methods. The QSC method is adaptable to essentially any centrifuge suitable for hydrogeologic applications, over a wide range of sizes and operating speeds. The simplified apparatus and greater adaptability of this method expands the potential for exploring situations that are common in nature but have been the subject of few laboratory investigations.

Received 10 January 2005; accepted 15 August 2005; published 16 November 2005.

Keywords: porous rocks; centrifugal technique; hydraulic properties; unsaturated flow.

Index Terms: 1875 Hydrology: Vadose zone; 1894 Hydrology: Instruments and techniques: modeling; 5139 Physical Properties of Rocks: Transport properties.

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Citation: Caputo, M. C., and J. R. Nimmo (2005), Quasi-steady centrifuge method for unsaturated hydraulic properties, Water Resour. Res., 41, W11504, doi:10.1029/2005WR003957.