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

This Article Figures Only Full Text Free Full Text (PDF) Free 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 Citing Articles via Google Scholar Google Scholar Articles by Wang, Z. Articles by Jury, W. A. Search for Related Content PubMed Articles by Wang, Z. Articles by Jury, W. A. GeoRef GeoRef Citation Agricola Articles by Wang, Z. Articles by Jury, W. A. Related Collections Preferential Flow Water Flow Models Unstable Flow/Fingering

Unstable Flow during Redistribution in Homogeneous Soil

^a Department of Earth and Environmental Sciences, California State University, Fresno, CA 93740
^b Department of Environmental Science, University of California, Riverside, CA 92521
^* Corresponding author (zwang{at}csufresno.edu)

Received 19 November 2002.

ABSTRACT

Two- and three-dimensional laboratory experiments were conducted in a large 1 by 1 m² Hele–Shaw cell and a 10-cm cylinder column to study the stability of the redistribution process in a uniformly packed porous medium of coarse sand. Our results demonstrate that fingers form and propagate rapidly as soon as infiltration stops when the soil is initially dry, but form more slowly and are larger when the soil is wet. Finger widths ranged from about 4.5 cm when the soil was dry to 17 cm when the soil was very wet, and the fraction of the cross-sectional area occupied by fingers also increased (from 36 to 66%). Finger velocities declined with time in all studies, with averages ranging from 3.6 to 9.6 cm min^-1. We demonstrated that ponded infiltration was stable and uniform in our system, so that the fingering we observed was not due to soil heterogeneity. The porous medium retained a memory of the fingers formed in the first experiment, so fingers formed in subsequent redistribution cycles followed the old finger paths, even after 28 d had elapsed. Fingers provide channels for rapid drainage of previously infiltrated water, especially when the soil ahead of the front is dry. Our findings clearly contradict predictions made by the Richards equation, which calculates stable flow during redistribution in homogeneous soil.

This article has been cited by other articles:

				T. Annaka and S. Hanayama Pressure Head Profile within Growing Fingers in Initially Dry Glass Beads Soil Sci. Soc. Am. J., May 16, 2007; 71(3): 901 - 908. [Abstract] [Full Text] [PDF]

				M. J. Nicholl and R. J. Glass Infiltration into an Analog Fracture: Experimental Observations of Gravity-Driven Fingering Vadose Zone J., November 11, 2005; 4(4): 1123 - 1151. [Abstract] [Full Text] [PDF]

				H. Cho, G. H. de Rooij, and M. Inoue The Pressure Head Regime in the Induction Zone During Unstable Nonponding Infiltration: Theory and Experiments Vadose Zone J., September 12, 2005; 4(4): 908 - 914. [Abstract] [Full Text] [PDF]

				Z. Wang, W. A. Jury, A. Tuli, and D.-J. Kim Unstable Flow during Redistribution: Controlling Factors and Practical Implications Vadose Zone J., May 1, 2004; 3(2): 549 - 559. [Abstract] [Full Text] [PDF]

				W. A. Jury, Z. Wang, and A. Tuli A Conceptual Model of Unstable Flow in Unsaturated Soil during Redistribution Vadose Zone J., February 1, 2003; 2(1): 61 - 67. [Abstract] [Full Text] [PDF]