Mass-transfer in soils with local stratification of hydraulic conductivity

Li, L., Barry, D. A., Culligan-Hensley, P. J. and Bajracharya, K. (1994) Mass-transfer in soils with local stratification of hydraulic conductivity. Water Resources Research, 30 11: 2891-2900. doi:10.1029/94WR01218

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Author Li, L.
Barry, D. A.
Culligan-Hensley, P. J.
Bajracharya, K.
Title Mass-transfer in soils with local stratification of hydraulic conductivity
Journal name Water Resources Research   Check publisher's open access policy
ISSN 0043-1397
1944-7973
Publication date 1994-11
Year available 1994
Sub-type Article (original research)
DOI 10.1029/94WR01218
Volume 30
Issue 11
Start page 2891
End page 2900
Total pages 10
Place of publication Washington, D.C., U.S.A
Publisher American Geophysical Union
Language eng
Abstract The two-region model was developed originally to describe nonsorbing chemical transport in soils with dead-end pores based on the concept of mobile and immobile regions in the soil. It has been shown that the model can simulate solute transport in soils with local stratification, or inhomogeneity, of hydraulic conductivity. However, the physical basis of the model becomes questionable, since the mobile-immobile region concept does not apply in stratified soils. In both soil types the nonequilibrium effect is caused by an apparent mass transfer process within the soil, as distinct from advection and diffusion. Where there are immobile regions, the mass transfer is due to solute interregion diffusion alone. In stratified soils the nonequilibrium mass transfer process is affected also by local flow variations. A conceptual model, numerical simulations, and laboratory experiments are presented to analyze these effects. For a given soil with fixed local stratification of hydraulic conductivity, it is shown that in the low-velocity range, the apparent mass transfer rate parameter, alpha, scales as V2/D (V is pore water velocity in the two-region model and D is the longitudinal dispersion coefficient), which implies that the mass transfer process is predominantly affected by local flow variations. When the velocity is relatively high, alpha is-proportional-to D(T)/h2 (D(T) is the interregion diffusion coefficient and h is the characteristic thickness of the stratified layers) and the mass transfer process is dominated by interregion diffusion. These scaling relations for alpha reflect the two mechanisms controlling the mass transfer process in locally stratified soils. They have implications for scaling of time-dependent mass transfer from laboratory models to prototype soils. In particular, the relationship alpha is-proportional-to V2/D leads to the conclusion that exact physical modeling of nonsorbing chemical transport coupled with apparent mass transfer in locally stratified soils may be viable.
Keyword Solute Transport
Porous-media
Structured Soils
Model
Movement
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collection: School of Civil Engineering Publications
 
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Created: Wed, 02 Jun 2010, 10:14:06 EST by Professor Ling Li on behalf of School of Civil Engineering