REVIEWS AND ANALYSES:

Sabine Goldberg, Louise J. Criscenti, David R. Turner, James A. Davis, and Kirk J. Cantrell

Adsorption–Desorption Processes in Subsurface Reactive Transport Modeling
This review attempts to summarize the current literature on adsorption-desorption reaction mechanisms, models for adsorption-desorption reactions at the molecular scale, empirical representations of adsorption-desorption equilibria, and field-scale applications of subsurface reactive transport modeling with adsorption-desorption equilibria.
Published online 1 August 2007; doi:10.2136/vzj2006.0085
Vadose Zone J 2007 6: 407-435. [Abstract] [Full Text] [Figures Only] [PDF]  

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

A Review of Multidimensional, Multifluid, Intermediate-Scale Experiments: Flow Behavior, Saturation Imaging, and Tracer Detection and Quantification
A review is presented of flow cell experiments involving characterization of NAPL flow behavior using imaging and detection/quantification with tracers. The techniques used for NAPL saturation mapping include photon-attenuation and photographic methods. Recommendations for future research at this laboratory scale are provided.
Published online 23 August 2007; doi:10.2136/vzj2006.0178
Vadose Zone J 2007 6: 610-637. [Abstract] [Full Text] [PDF]  

ORIGINAL RESEARCH PAPERS:

J. Bachmann, M. Deurer, and G. Arye

Modeling Water Movement in Heterogeneous Water-Repellent Soil: 1. Development of a Contact Angle–Dependent Water-Retention Model
We present a general model for describing the movement of water in soils with variable pore-surface properties. It applies for wettable, subcritically water repellent, and hydrophobic soils. A microscopic water-content and time-dependent contact angle is coupled with the macroscopic water retention function. Few additional parameters are needed.
Published online 1 August 2007; doi:10.2136/vzj2006.0060
Vadose Zone J 2007 6: 436-445. [Abstract] [Full Text] [Figures Only] [PDF]  

M. Deurer and J. Bachmann

Modeling Water Movement in Heterogeneous Water-Repellent Soil: 2. A Conceptual Numerical Simulation
We test a general model for describing water in texturally heterogeneous soils exhibiting various degrees of water repellency by simulating a drying-rewetting cycle in soils. For the hydrophobic soils we predict distribution, fingering and redistribution zones. With rewetting the fingers slowly widen and dissipate.
Published online 1 August 2007; doi:10.2136/vzj2006.0061
Vadose Zone J 2007 6: 446-457. [Abstract] [Full Text] [Figures Only] [PDF]  

R. J. Lenhard and P. Meakin

Water Behavior in Layered Porous Media with Discrete Flow Channels: Results of a Large-Scale Experiment
An experiment focusing on water movement into discrete flow channels was conducted. A steady or quasi-periodic "leaking" of water occurred, contrary to capillary break theory. This work demonstrates that surprising and complex behavior can occur in relatively simple and well-characterized systems with scales on the order of several meters.
Published online 1 August 2007; doi:10.2136/vzj2006.0125
Vadose Zone J 2007 6: 458-470. [Abstract] [Full Text] [Figures Only] [PDF]  

F. Fagerlund, T.H. Illangasekare, and A. Niemi

Nonaqueous-Phase Liquid Infiltration and Immobilization in Heterogeneous Media: 1. Experimental Methods and Two-Layered Reference Case
A methodology to dynamically measure nonaqueous-phase liquid (NAPL) migration in space and time using a multiple-energy x-ray attenuation technique is presented. Flow and entrapment of NAPL in a saturated layered formation were studied, and methods of characterizing entrapment architecture were tested. The saturation history dependence of entrapment was also demonstrated.
Published online 1 August 2007; doi:10.2136/vzj2006.0171
Vadose Zone J 2007 6: 471-482. [Abstract] [Full Text] [Figures Only] [PDF]  

F. Fagerlund, T.H. Illangasekare, and A. Niemi

Nonaqueous-Phase Liquid Infiltration and Immobilization in Heterogeneous Media: 2. Application to Stochastically Heterogeneous Formations
Spatially correlated random permeability fields were carefully built in a saturated 2D sand tank creating systems of complex but well-known heterogeneity. Non-aqueous phase liquid migration and entrapment at capillary barriers and by snap-off processes were studied taking precise measurements of fluid saturations in space and time using an x-ray-attenuation technique.
Published online 1 August 2007; doi:10.2136/vzj2006.0172
Vadose Zone J 2007 6: 483-495. [Abstract] [Full Text] [Figures Only] [PDF]  

Edwin P. Weeks and Peter B. McMahon

Nitrous Oxide Fluxes from Cultivated Areas and Rangeland: U.S. High Plains
Depth profiles of chlorofluorocarbon concentrations in soil gas at nine sites of irrigated cropland and rangeland in the High Plains were used to calibrate a gas-phase diffusive transport model. Vadose-zone measurements of nitrous oxide, a significant greenhouse gas, were used with the calibrated model to estimate its flux to the atmosphere from the various sites.
Published online 1 August 2007; doi:10.2136/vzj2006.0164
Vadose Zone J 2007 6: 496-510. [Abstract] [Full Text] [Figures Only] [PDF]  

Sikiru A. Amidu and John A. Dunbar

Geoelectric Studies of Seasonal Wetting and Drying of a Texas Vertisol
We examined the seasonal dynamics of moisture in a Vertisol using the electrical-resistivity geophysical method. Results show that there are three soil moisture regimes and that seasonal hydrodynamics of the soil are influenced by microrelief variability and cracks. Implications of the results to agricultural management and soil taxonomy are discussed.
Published online 1 August 2007; doi:10.2136/vzj2007.0005
Vadose Zone J 2007 6: 511-523. [Abstract] [Full Text] [Figures Only] [PDF]  

Vahedberdi Sheikh and E. Emiel van Loon

Comparing Performance and Parameterization of a One-Dimensional Unsaturated Zone Model across Scales
Does aggregation level matter when only considering soil moisture? Can we derive a meta-model to scale model performance or effective parameters? Are some model performance criteria more scale independent than others? These questions were addressed by applying the SWAP model to observations from a small catchment in the Netherlands.
Published online 23 August 2007; doi:10.2136/vzj2006.0077
Vadose Zone J 2007 6: 638-650. [Abstract] [Full Text] [Figures Only] [PDF]  

Horst H. Gerke, Jaromir Dusek, Tomas Vogel, and J. Maximilian Köhne

Two-Dimensional Dual-Permeability Analyses of a Bromide Tracer Experiment on a Tile-Drained Field
This paper describes an improved two-dimensional numerical analysis of preferential water and bromide movement toward tile drains in structured glacial till soil. Dual- as compared with single-permeability model results indicate the importance of soil surface boundary conditions and plot- and field-scale mixing in addition to local nonequilibrium effects.
Published online 23 August 2007; doi:10.2136/vzj2007.0033
Vadose Zone J 2007 6: 651-667. [Abstract] [Full Text] [Figures Only] [PDF]  

Sven Altfelder, Wilhelmus H. M. Duijnisveld, Thilo Streck, Gunnar Meyenburg, and Jens Utermann

Quantifying the Influence of Uncertainty and Variability on Groundwater Risk Assessment for Trace Elements
A parallel soil column model quantifying trace element transport at the field scale for situations where site data are scarce is described. In combination with a two-dimensional Monte Carlo approach, it allows to distinguish effects of (irreducible) variability and (reducible) uncertainty on predicted concentrations.
Published online 23 August 2007; doi:10.2136/vzj2006.0148
Vadose Zone J 2007 6: 668-678. [Abstract] [Full Text] [Figures Only] [PDF]  

COMMENTS:

Tom Schröder, M. Javaux, J. Vanderborght, and H. Vereecken

Comment on "Root Water Extraction and Limiting Soil Hydraulic Conditions Estimated by Numerical Simulation"
Published online 1 August 2007; doi:10.2136/vzj2007.0036
Vadose Zone J 2007 6: 524-526. [Full Text] [Figures Only] [PDF]  

Quirijn de Jong van Lier, Klaas Metselaar, and Jos C. van Dam

Response to "Comment on ‘Root Water Extraction and Limiting Soil Hydraulic Conditions Estimated by Numerical Simulation’"
Published online 1 August 2007; doi:10.2136/vzj2007.0042L
Vadose Zone J 2007 6: 527-528. [Full Text] [PDF]  

ERRATA:

Carlos M. Regalado, Axel Ritter, and Rosa M. Rodríguez-González

Performance of the Commercial WET Capacitance Sensor as Compared with Time Domain Reflectometry in Volcanic Soils
Published online 1 August 2007; doi:10.2136/vzj2006.0138er
Vadose Zone J 2007 6: 529. [Full Text] [PDF]  

SPECIAL SECTION: GROUNDWATER RESOURCES ASSESSMENT UNDER THE PRESSURES OF HUMANITY AND CLIMATE CHANGE:

Timothy R. Green, Makoto Taniguchi, and Henk Kooi

Potential Impacts of Climate Change and Human Activity on Subsurface Water Resources
The guest editors introduce the special section Groundwater Resources Assessment under the Pressures of Humanity and Climate Change (GRAPHIC) derived from the conference by the same name that was held in Kyoto, Japan in 2006. Sponsored by UNESCO's International Hydrological Program, GRAPHIC is a collaborative effort and umbrella for international research and education. The conference was hosted by the Research Institute for Humanity and Nature, Japan.
Published online 23 August 2007; doi:10.2136/vzj2007.0098
Vadose Zone J 2007 6: 531-532. [Full Text] [PDF]  

Jason J. Gurdak, Randall T. Hanson, Peter B. McMahon, Breton W. Bruce, John E. McCray, Geoffrey D. Thyne, and Robert C. Reedy

Climate Variability Controls on Unsaturated Water and Chemical Movement, High Plains Aquifer, USA
Spectral analysis of hydrologic time series and reconstruction of frequency components reveal that unsaturated water and chemical fluxes, including recharge, respond to interannual to multidecadal climate cycles, particularly the Pacific Decadal Oscillation. Using this conceptualization, a method is presented to estimate climate-varying recharge.
Published online 23 August 2007; doi:10.2136/vzj2006.0087
Vadose Zone J 2007 6: 533-547. [Abstract] [Full Text] [Figures Only] [PDF]  

Fumi Sugita and Kazuro Nakane

Combined Effects of Rainfall Patterns and Porous Media Properties on Nitrate Leaching
Effects of rainfall patterns on nitrate leaching in homogeneous and heterogeneous porous media were investigated. Nitrate leaches only under extreme rainfall in both media, whereas considerable degradation and large spreading are observed only in heterogeneous porous media. The increase of nitrate leaching by potential climate change is suggested.
Published online 23 August 2007; doi:10.2136/vzj2006.0095
Vadose Zone J 2007 6: 548-553. [Abstract] [Full Text] [Figures Only] [PDF]  

Lieke van Roosmalen, Britt S. B. Christensen, and Torben O. Sonnenborg

Regional Differences in Climate Change Impacts on Groundwater and Stream Discharge in Denmark
Regional climate model data are used in an integrated hydrological model to study the effects of future climate change. The main focus of this study is groundwater recharge, although the changes in stream discharge are also presented. The results show a clear influence of the geology and climatology of the study areas on the simulated effects.
Published online 23 August 2007; doi:10.2136/vzj2006.0093
Vadose Zone J 2007 6: 554-571. [Abstract] [Full Text] [Figures Only] [PDF]  

Jeroen Aerts, Ralph Lasage, Wisse Beets, Hans de Moel, Gideon Mutiso, Sam Mutiso, and Arjen de Vries

Robustness of Sand Storage Dams under Climate Change
Climate change will have an impact on potential evaporation through an increase in average temperature. The goals of this work were to examine the storage capacity of sand dams, process historical climate data and future climate change scenarios, and model both current water availability and future water availability under climate change.
Published online 23 August 2007; doi:10.2136/vzj2006.0097
Vadose Zone J 2007 6: 572-580. [Abstract] [Full Text] [Figures Only] [PDF]  

Ian White, Tony Falkland, Taboia Metutera, Eita Metai, Marc Overmars, Pascal Perez, and Anne Dray

Climatic and Human Influences on Groundwater in Low Atolls
The quality and quantity of atoll groundwater are susceptible to ENSO events and human settlement. Infiltration galleries minimize salinisation and provide estimates of the hydraulic conductivity of unconsolidated coral sediments. Strategies for protecting groundwater and increasing resilience of island communities to climate change are discussed.
Published online 23 August 2007; doi:10.2136/vzj2006.0092
Vadose Zone J 2007 6: 581-590. [Abstract] [Full Text] [Figures Only] [PDF]  

Makoto Taniguchi, Takeshi Uemura, and Karen Jago-on

Combined Effects of Urbanization and Global Warming on Subsurface Temperature in Four Asian Cities
Subsurface termperatures in Asian cities were analyzed to evaluate the effects of surface warming due to urbanization. The magnitude of surface warming and the depth apart from the the geothermal gradient show the magnitude of heat island and elapsed time from the start of surface warming.
Published online 23 August 2007; doi:10.2136/vzj2006.0094
Vadose Zone J 2007 6: 591-596. [Abstract] [Full Text] [Figures Only] [PDF]  

Timothy R. Green, Bryson C. Bates, Stephen P. Charles, and P. Mick Fleming

Physically Based Simulation of Potential Effects of Carbon Dioxide–Altered Climates on Groundwater Recharge
A new method for simulating double carbon dioxide climate change effects on dynamic equilibrium vegetation and soil-water regimes affecting groundwater recharge was demonstrated for two sites in Australia with Mediterranean and subtropical climates. Potential changes in recharge versus rainfall were highly nonlinear and varied with the soil and vegetation.
Published online 23 August 2007; doi:10.2136/vzj2006.0099
Vadose Zone J 2007 6: 597-609. [Abstract] [Full Text] [Figures Only] [PDF]  

TECHNICAL NOTES:

H. H. Liu, Y. Q. Zhang, and F. J. Molz

Scale Dependence of the Effective Matrix Diffusion Coefficient: Some Analytical Results
We develop analytical expressions for the effective matrix diffusion coefficient for two simple fracture-matrix systems and demonstrate that heterogeneities in the rock matrix at different scales may contribute to the scale dependence of the effective matrix diffusion coefficient.
Published online 23 August 2007; doi:10.2136/vzj2006.0140
Vadose Zone J 2007 6: 679-683. [Abstract] [Full Text] [Figures Only] [PDF]  

BOOK REVIEWS:

Steven F. Carle

Geostatistical Analysis of Compositional Data
Edited by Vera Pawlowsky-Glahn and Ricardo Olea. International Association for Mathematical Geology, Studies in Mathematical Geology No. 7. Oxford University Press, New York. 2004. Hardcover, 304 pp. ISBN 0-19-517166-7.
Published online 23 August 2007; doi:10.2136/vzj2007.0063br
Vadose Zone J 2007 6: 684-685. [Full Text] [PDF]  

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