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 Jury, W. A. Articles by Tuli, A. Search for Related Content PubMed Articles by Jury, W. A. Articles by Tuli, A. GeoRef GeoRef Citation Agricola Articles by Jury, W. A. Articles by Tuli, A. Related Collections Preferential Flow Water Flow Models Unstable Flow/Fingering

A Conceptual Model of Unstable Flow in Unsaturated Soil during Redistribution

^a Department of Environmental Sciences, University of California, Riverside, CA 92521
^b Department of Environmental Sciences, Calif. State Univ. Fresno, CA 93740
^* Corresponding author (wajury{at}mail.ucr.edu)

Received 7 August 2002.

ABSTRACT

A conceptual model is presented that represents the development of unstable flow in uniform soils during redistribution. The flow instability results in the propagation of fingers that drain water from the wetted soil matrix until equilibrium is reached. The model uses soil retention and hydraulic functions, plus relationships describing finger size and spatial frequency. The model assumes that all soils are unstable during redistribution, but shows that only coarse-textured soils will form fingers capable of moving appreciable distances. Once it forms, a finger moves downward at a rate governed by the rate of loss of water from the soil matrix, which can be predicted from the hydraulic conductivity function. Fingers are assumed to stay narrow as a result of hysteresis, which prevents lateral diffusion. The draining front in the soil matrix between the fingers is assumed to cease downward movement because water pressure drops below the threshold water-entry matric potential. The threshold potential is not present in the conventional Richards equation of soil water flow, which explains why unstable flow is not predicted by widely used simulation model codes.

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]

				Z. Wang, A. Tuli, and W. A. Jury Unstable Flow during Redistribution in Homogeneous Soil Vadose Zone J., February 1, 2003; 2(1): 52 - 60. [Abstract] [Full Text] [PDF]