HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Figures Only Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Google Scholar Articles by Podgorney, R. K. Articles by Fairley, J. P. PubMed Articles by Podgorney, R. K. Articles by Fairley, J. P. GeoRef GeoRef Citation Agricola Articles by Podgorney, R. K. Articles by Fairley, J. P. Related Collections Hydraulic Conductivity/Relative Permeability Water Retention/Capillary Pressure Preferential Flow

SPECIAL SECTION: TOUGH2

Investigation of Episodic Flow from Unsaturated Porous Media into a Macropore

^a Idaho National Lab., Modeling and Measurement Group, Idaho Falls, ID 83404 and Dep. of Geological Sciences, Univ. of Idaho, Moscow, ID 83844-3022
^b Dep. of Geological Sciences, Univ. of Idaho, Moscow, ID 83844-3022
^* Corresponding author (robert.podgorney{at}inl.gov).

Received 28 July 2006.

The recent literature contains numerous observations of episodic or intermittent flow in unsaturated flow systems under both constant flux and ponded boundary conditions. Flow systems composed of a heterogeneous porous media, as well as discrete fracture networks, have been cited as examples of systems that can exhibit episodic flow. Episodic outflow events are significant because relatively large volumes of water can move rapidly through an unsaturated system, carrying water and contaminants to depth greatly ahead of a wetting front predicted by a one-dimensional, gravity-driven diffusive infiltration model. In this study, we model the behavior of water flow through a sand column underlain by an impermeable-walled macropore. Relative permeability and capillary pressure relationships were developed that capture the complex interrelationships between the macropore and the overlying porous media that control flow out of the system. The potential for episodic flow is assessed and compared to results of conventional modeling approaches and experimental data from the literature. Model results using coupled matrix–macropore relative permeability and capillary pressure relationships capture the behavior observed in laboratory experiments remarkably well, while simulations using conventional relative permeability and capillary pressure functions fail to capture some of the observed flow dynamics. Capturing the rapid downward movement of water suggests that the matrix-macropore capillary pressure and relative permeability functions developed have the potential to improve descriptions of flow and transport processes in heterogeneous, variably saturated media.

This article has been cited by other articles:

				H.-H. Liu and T. H. Illangasekare Preface: Recent Advances in Modeling Multiphase Flow and Transport with the TOUGH Family of Codes Vadose Zone J., February 25, 2008; 7(1): 284 - 286. [Abstract] [Full Text] [PDF]