ORIGINAL RESEARCH PAPERS:

M. Javaux, J. Vanderborght, R. Kasteel, and M. Vanclooster

Three-Dimensional Modeling of the Scale- and Flow Rate-Dependency of Dispersion in a Heterogeneous Unsaturated Sandy Monolith
The three-dimensional structure of a heterogeneous sandy subsoil was implemented in a deterministic model to reproduce the observed scale- and flow rate-dependency of the dispersion under variably saturated conditions. In addition to the significant macrostructure, a microstructure description was necessary to improve simulation of the observations.
Published online 27 April 2006; doi:10.2136/vzj2005.0056
Vadose Zone J 2006 5: 515-528. [Abstract] [Full Text] [Figures Only] [PDF]  

M. Javaux, R. Kasteel, J. Vanderborght, and M. Vanclooster

Interpretation of Dye Transport in a Macroscopically Heterogeneous, Unsaturated Subsoil with a One-Dimensional Model
A one-dimensional model was used to identify physical and chemical processes affecting the transport of Brilliant Blue through a column of undisturbed subsoil. In addition to the macroscopic heterogeneity, results indicate that unsaturated flow conditions may affect the transport by reducing accessibility of the sorption sites, thus decreasing the sorption rate.
Published online 27 April 2006; doi:10.2136/vzj2005.0085
Vadose Zone J 2006 5: 529-538. [Abstract] [Full Text] [Figures Only] [PDF]  

Martine Bohy, Lotfi Dridi, Gerhard Schäfer, and Olivier Razakarisoa

Transport of a Mixture of Chlorinated Solvent Vapors in the Vadose Zone of a Sandy Aquifer: Experimental Study and Numerical Modeling
The fate and transport of a mixture of chlorinated solvents in an artificial sandy aquifer are studied. The simultaneously measured TCE and PCE volatilization rates are compared with the predictions of a multiphase, multicomponent numerical model and a quasianalytical approach based on Fick's first law.
Published online 27 April 2006; doi:10.2136/vzj2005.0079
Vadose Zone J 2006 5: 539-553. [Abstract] [Full Text] [Figures Only] [PDF]  

S. Assouline

Modeling the Relationship between Soil Bulk Density and the Water Retention Curve
Bulk density increase, a common occurrence in agricultural soils, affects many aspects of the soil-water-plant-atmosphere continuum. An empirical model for predicting the effect of bulk density increases on the soil water retention curve is presented. The model is suitable for many agricultural, hydrological, and environmental applications.
Published online 27 April 2006; doi:10.2136/vzj2005.0083
Vadose Zone J 2006 5: 554-563. [Abstract] [Full Text] [Figures Only] [PDF]  

Liping Pang, Chris Nokes, Jirka Simunek, Heather Kikkert, and Ross Hector

Modeling the Impact of Clustered Septic Tank Systems on Groundwater Quality
HYDRUS-2D was used to simulate the cumulative effect of clustered septic tank systems on nitrate and fecal coliforms in groundwater in a rural community, and simulated results agree well with monitoring data. Sensitivity analysis was performed for input parameters.
Published online 26 May 2006; doi:10.2136/vzj2005.0108
Vadose Zone J 2006 5: 599-609. [Abstract] [Full Text] [Figures Only] [PDF]  

Cynthia L. Dinwiddie, Kelly Keighley Bradbury, Ronald N. McGinnis, Randall W. Fedors, and David A. Ferrill

Fault Zone Deformation Overprints Permeability of Nonwelded Ignimbrite: Chalk Cove Fault, Bishop Tuff, Bishop, California
The authors report on a multidisciplinary field study of secondary heterogeneities in faulted nonwelded ignimbrites. Results suggest that three features of fault-zone deformation, which are discussed in this article, may constrain the spatial extent of lateral flow in unsaturated nonwelded ignimbrites.
Published online 26 May 2006; doi:10.2136/vzj2005.0062
Vadose Zone J 2006 5: 610-627. [Abstract] [Full Text] [Figures Only] [PDF]  

K. Schwärzel, J. Simunek, H. Stoffregen, G. Wessolek, and M. Th. van Genuchten

Estimation of the Unsaturated Hydraulic Conductivity of Peat Soils: Laboratory versus Field Data
An inverse parameter optimization method was applied to a peat soil to estimate the hydraulic parameters of the soil. Parameter estimation was based on data acquired from experiments using groundwater lysimeters with and without vegetation and on laboratory measurements on small cores.
Published online 26 May 2006; doi:10.2136/vzj2005.0061
Vadose Zone J 2006 5: 628-640. [Abstract] [Full Text] [Figures Only] [PDF]  

G. Schnaar and M. L. Brusseau

Characterizing Pore-Scale Configuration of Organic Immiscible Liquid in Multiphase Systems With Synchrotron X-Ray Microtomography
X-Ray microtomography was used to acquire three-dimensional images of an organic liquid in natural porous media. Images were obtained for both two-phase and three-phase systems. The morphology of the organic liquid varied significantly in the three-phase versus two-phase systems due to the presence of thin organic liquid films in contact with air.
Published online 26 May 2006; doi:10.2136/vzj2005.0063
Vadose Zone J 2006 5: 641-648. [Abstract] [Full Text] [Figures Only] [PDF]  

Tjalfe G. Poulsen, Per Moldrup, Lis W. de Jonge, and Toshiko Komatsu

Colloid and Bromide Transport in Undisturbed Soil Columns: Application of Two-Region Model
Bromide tracer and colloid transport in undisturbed soil was investigated. Colloid transport velocity was three to four times that of Br, indicating size exclusion of colloids. Results further indicate that colloid leaching is controlled by soil structure and macropore flow rather than by the amount of dispersible colloids present in the soil.
Published online 26 May 2006; doi:10.2136/vzj2005.0068
Vadose Zone J 2006 5: 649-656. [Abstract] [Full Text] [Figures Only] [PDF]  

Jens T. Birkholzer and Yingqi Zhang

The Impact of Fracture–Matrix Interaction on Thermal–Hydrological Conditions in Heated Fractured Rock
Dual-continuum simulations of a laboratory heater experiment were conducted to evaluate the impact of fracture-matrix interaction in strongly heated, partially saturated fractured rock. Our sensitivity study indicates that the heat transfer from the rock matrix to the liquid-phase flow in the fractures is strongly reduced due to flow channeling.
Published online 26 May 2006; doi:10.2136/vzj2005.0071
Vadose Zone J 2006 5: 657-672. [Abstract] [Full Text] [Figures Only] [PDF]  

John S. McCartney and Jorge G. Zornberg

Correction of Lightning Effects on Water Content Reflectometer Soil Moisture Data
This study examined the effects of lightning strikes on soil moisture content data inferred using water content reflectometer probes during a 6-yr field monitoring study. A practical methodology was developed for preliminary correction of soil moisture data from affected probes.
Published online 26 May 2006; doi:10.2136/vzj2005.0074
Vadose Zone J 2006 5: 673-683. [Abstract] [Full Text] [Figures Only] [PDF]  

T. B. Ramos, M. C. Gonçalves, J. C. Martins, M. Th. van Genuchten, and F. P. Pires

Estimation of Soil Hydraulic Properties from Numerical Inversion of Tension Disk Infiltrometer Data
Parameter estimation from tension infiltrometer data and from laboratory methods is compared. Combined optimal data in the inverse analysis, the importance of water contents measurements, and several other complexities are demonstrated, which will be helpful for practitioners in routine field measurement determinations of hydraulic properties.
Published online 26 May 2006; doi:10.2136/vzj2005.0076
Vadose Zone J 2006 5: 684-696. [Abstract] [Full Text] [Figures Only] [PDF]  

S. Assouline

Modeling the Relationship between Soil Bulk Density and the Hydraulic Conductivity Function
Compaction can have a dramatic impact on flow and transport processes in soils. Approaches were formulated to predict the saturated and unsaturated hydraulic conductivity functions of compacted soils.
Published online 26 May 2006; doi:10.2136/vzj2005.0084
Vadose Zone J 2006 5: 697-705. [Abstract] [Full Text] [Figures Only] [PDF]  

Kari A. Winfield, John R. Nimmo, John A. Izbicki, and Peter M. Martin

Resolving Structural Influences on Water-Retention Properties of Alluvial Deposits
Measured water retention of core samples shows the influence of systematically different particle arrangements associated with fluvial and debris-flow deposition. These structural differences had much less influence than texture, though inclusion of structural information in property-transfer models improved the prediction of hydraulic properties.
Published online 26 May 2006; doi:10.2136/vzj2005.0088
Vadose Zone J 2006 5: 706-719. [Abstract] [Full Text] [Figures Only] [PDF]  

Darren G. Meadows, Michael H. Young, and Eric V. McDonald

Estimating the Fine Soil Fraction of Desert Pavements Using Ground Penetrating Radar
The clay-rich surface horizon in desert pavement environments significantly impacts the attenuation of electromagnetic waves from GPR. Combining early-time signal amplitude and a nominal measure of soil development, we estimated the fine soil fraction and saturated hydraulic conductivity of the surface layer of a well-developed desert pavement.
Published online 26 May 2006; doi:10.2136/vzj2005.0095
Vadose Zone J 2006 5: 720-730. [Abstract] [Full Text] [Figures Only] [PDF]  

R. P. Ewing and A. G. Hunt

Dependence of the Electrical Conductivity on Saturation in Real Porous Media
We developed a new method for characterizing a soil's electrical conductivity as a function of saturation. The method is a generalized form of Archie's Law derived from percolation theory, so it is physically based and yields meaningful parameters. We discuss the method's limitations and its application to real-world data.
Published online 26 May 2006; doi:10.2136/vzj2005.0107
Vadose Zone J 2006 5: 731-741. [Abstract] [Full Text] [Figures Only] [PDF]  

Michael H. Young, William Albright, Karl F. Pohlmann, Greg Pohll, Walter H. Zachritz, Stephen Zitzer, David S. Shafer, Irene Nester, and Layi Oyelowo

Incorporating Parametric Uncertainty in the Design of Alternative Landfill Covers in Arid Regions
Monte Carlo simulations and site-specific data were used to design alternative landfill covers. Results show that threshold design parameters needed to limit deep flux to <0.5 cm per year, differ based on the relationship between the saturated hydraulic conductivity of the surface soil, cover thickness, and plant cover percentage.
Published online 26 May 2006; doi:10.2136/vzj2005.0112
Vadose Zone J 2006 5: 742-750. [Abstract] [Full Text] [Figures Only] [PDF]  

Ole K. Olmanson and Tyson E. Ochsner

Comparing Ambient Temperature Effects on Heat Pulse and Time Domain Reflectometry Soil Water Content Measurements
Colocated measurements for a wide temperature range facilitate comparison of the effects of ambient temperature on heat pulse and TDR water content measurements. In an attempt to reduce the temperature effects, an existing correction is applied to the TDR data, and a new correction is developed for the heat pulse data.
Published online 26 May 2006; doi:10.2136/vzj2005.0114
Vadose Zone J 2006 5: 751-756. [Abstract] [Full Text] [Figures Only] [PDF]  

Brad D. Lee, Byron J. Jenkinson, James A. Doolittle, Richard S. Taylor, and J. Wes Tuttle

Electrical Conductivity of a Failed Septic System Soil Absorption Field
Field methods utilizing non-invasive electromagnetic induction to detect septic systems and effluent plumes are presented. Results from this study suggest that electromagnetic induction is a promising technique to identify the location of septic system components, failed septic systems and their associated effluent plumes.
Published online 26 May 2006; doi:10.2136/vzj2005.0116
Vadose Zone J 2006 5: 757-763. [Abstract] [Full Text] [Figures Only] [PDF]  

Raziuddin Khaleel and K. Prasad Saripalli

An Air–Water Interfacial Area Based Variable Tortuosity Model for Unsaturated Sands
A new saturation-dependent tortuosity definition is presented that is based on immiscible fluid (air-water) interfacial area. The methodology was tested by comparing the variable tortuosity based unsaturated hydraulic conductivity predictions with measurements for repacked sands; a good agreement was obtained.
Published online 26 May 2006; doi:10.2136/vzj2005.0129
Vadose Zone J 2006 5: 764-776. [Abstract] [Full Text] [Figures Only] [PDF]  

K. P. Saripalli, V. L. Freedman, B. P. McGrail, and P. D. Meyer

Characterization of the Specific Solid–Water Interfacial Area–Water Saturation Relationship and Its Import to Reactive Transport
A model is presented that relates specific solid-water interfacial area to water saturation and quantifies the influence of area on the rate equation for mineral dissolution. Reactive transport modeling using this model demonstrated the effect of dynamic interfacial area on contaminant transport during transient unsaturated flow.
Published online 26 May 2006; doi:10.2136/vzj2005.0145
Vadose Zone J 2006 5: 777-783. [Abstract] [Full Text] [Figures Only] [PDF]  

Hirotaka Saito, Jiri Simunek, and Binayak P. Mohanty

Numerical Analysis of Coupled Water, Vapor, and Heat Transport in the Vadose Zone
The coupled movement of water, vapor, and heat in the vadose zone, as well as interactions with the mass and energy balance at the soil surface, were implemented in the HYDRUS-1D code. The model was evaluated using field soil temperature and water content data collected in Riverside, CA.
Published online 26 May 2006; doi:10.2136/vzj2006.0007
Vadose Zone J 2006 5: 784-800. [Abstract] [Full Text] [Figures Only] [PDF]  

NOTES:

Janna M. Levin, Janet S. Herman, George M. Hornberger, and James E. Saiers

Colloid Mobilization from a Variably Saturated, Intact Soil Core
Mechanisms of colloid mobilization in an unsaturated soil core are investigated. Intervention analysis demonstrated significant increases in the colloid-mass flux with increases in soil water pressure head. Results indicate that a colloid-supply mechanism influences colloid mobilization during steady flow.
Published online 27 April 2006; doi:10.2136/vzj2005.0102
Vadose Zone J 2006 5: 564-569. [Abstract] [Full Text] [Figures Only] [PDF]  

Naftali Lazarovitch, Alon Ben-Gal, and Uri Shani

An Automated Rotating Lysimeter System for Greenhouse Evapotranspiration Studies
We present a rotating structure that significantly enhances uniform growing conditions for plants grown in lysimeters and facilitates accurate water and solute balance measurements. This apparatus has good potential for use as a tool for studying processes occurring in the vadose zone.
Published online 26 May 2006; doi:10.2136/vzj2005.0137
Vadose Zone J 2006 5: 801-804. [Abstract] [Full Text] [Figures Only] [PDF]  

E. D. Mattson, K. E. Baker, C. D. Palmer, C. R. Breckenridge, J. M. Svoboda, and R. W. Smith

A Flexible Water Content Probe for Unsaturated Soil Column Experiments
A side-by-side comparison is presented of a commercially available soil water content probe with rigid electrodes and a modified electrode design with flexible electrodes. Laboratory testing results indicate that the flexible electrode design response is equivalent to or better than the commercial design and allows for easier soil packing in a column.
Published online 26 May 2006; doi:10.2136/vzj2006.0139
Vadose Zone J 2006 5: 805-808. [Abstract] [Full Text] [Figures Only] [PDF]  

REVIEWS AND ANALYSES:

M. Oostrom, J. H. Dane, and T. W. Wietsma

A Review of Multidimensional, Multifluid Intermediate-Scale Experiments: Nonaqueous Phase Liquid Dissolution and Enhanced Remediation
A review is presented of flow cell experiments related to aqueous dissolution and enhanced remediation of pooled and entrapped nonaqueous phase liquids. The enhanced remediation category discusses experiments investigating surfactant flushing, dense brine strategies, and other techniques. Suggestions for future flow cell research are provided.
Published online 26 May 2006; doi:10.2136/vzj2005.0125
Vadose Zone J 2006 5: 570-598. [Abstract] [Full Text] [PDF]  

COMMENTS:

G.W. Gee, C.H. Benson, and W.H. Albright

Comment on "Evaluation of Evapotranspirative Covers for Waste Containment in Arid and Semiarid Regions in the Southwestern USA"
Published online 26 May 2006; doi:10.2136/vzj2005.0090
Vadose Zone J 2006 5: 809-812. [Full Text] [Figures Only] [PDF]  

B. R. Scanlon, R. C. Reedy, K. E. Dwyer, and S. F. Dwyer

Response to "Comments on ‘Evaluation of Evapotranspirative Covers for Waste Containment in Arid and Semiarid Regions in the Southwestern USA’"
Published online 26 May 2006; doi:10.2136/vzj2006.0010
Vadose Zone J 2006 5: 813-814. [Full Text] [PDF]  

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