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Previous Next 		Contents: May 2008, Volume 7, Issue 2   [Index by Author] 
Down ORIGINAL RESEARCH
Down TECHNICAL NOTES
Down SPECIAL SECTION: MULTISCALE MAPPING
Down SPECIAL SECTION: VADOSE ZONE MODELING

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To see an article, click its [Full Text] link. To review many abstracts, check the boxes to the left of the titles you want, and click the 'Get All Checked Abstract(s)' button. To see one abstract at a time, click its [Abstract] link.

ORIGINAL RESEARCHBack

Augustus C. Resurreccion, Per Moldrup, Ken Kawamoto, Seiko Yoshikawa, Dennis E. Rolston, and Toshiko Komatsu

The classical gas diffusivity model by Buckingham was revisited to evaluate the variation of the pore continuity factor (X) with soil moisture conditions. The Buckingham model with X varying with matric potential and coupled with a two-region water retention model described well the gas diffusivity behavior in aggregated volcanic ash soils.
Published online 14 April 2008; doi: 10.2136/vzj2007.0058
Vadose Zone J Apr 14 2008: 397–405 [Abstract] [Full Text] [PDF]  

G. Gargiulo, S. A. Bradford, J. Simunek, P. Ustohal, H. Vereecken, and E. Klumpp

Knowledge of factors that influence bacteria transport behavior in the vadose zone is needed to protect drinking water supplies from contamination and to develop improved bioremediation strategies. We investigate the transport and deposition of representative hydrophobic and hydrophilic bacteria strains in sand at different water saturations. The amount of bacteria retained in the sand increased with decreasing water saturation, especially for the more hydrophobic strain that formed larger cell aggregates. Straining likely accounts for these observations because it increases in magnitude with increasing cell/aggregate size, and when a greater fraction of water flows through a larger number of small pore spaces with decreasing water saturation.
Published online 1 May 2008; doi: 10.2136/vzj2007.0068
Vadose Zone J May 1 2008: 406–419 [Abstract] [Full Text] [PDF]  

Lynn M. Dudley, Alon Ben-Gal, and Uri Shani

Concern has been expressed that prolonged irrigation with poor quality water in amounts less than required to refill the soil profile and leach salt left from previous irrigations in an effort to maximize water use and minimize groundwater contamination may eventually cause crop failure and destroy the soil resource. As salt accumulates, however, transpiration and yield will decrease and a fraction of the irrigation water subsequently becomes drainage limiting due to salt storage in the root zone. Through a series of computer simulations, it was found that there was a minimum value of the leaching fraction for every level of salinity and that plant-irrigation-drainage relationships are highly self-regulating.
Published online 14 April 2008; doi: 10.2136/vzj2007.0103
Vadose Zone J Apr 14 2008: 420–425 [Abstract] [Full Text] [PDF]  

J. A. Huisman, C. P. Lin, L. Weihermüller, and H. Vereecken

The accuracy of bulk electrical conductivity measurements with time domain reflectometry (TDR) was determined. Uncertainty introduced by probe calibration and reproducibility of TDR measurements was considered. An analytical expression to calculate the probe constant directly was also evaluated.
Published online 14 April 2008; doi: 10.2136/vzj2007.0139
Vadose Zone J Apr 14 2008: 426–433 [Abstract] [Full Text] [PDF]  

Fuli Wang

A comprehensive two-dimensional N-dynamics model is presented to simulate pasture growth, heat transport, water flow, solute transport, and various N transformations in soils over dairy farmland. The model is used to quantitatively analyze the most important factors that affect total N-leaching and its spatial variations caused by urine patches.
Published online 27 May 2008; doi: 10.2136/vzj2007.0128
Vadose Zone J May 27 2008: 439–452 [Abstract] [Full Text] [PDF]  

TECHNICAL NOTESBack

Jan Mertens, Valentijn Tuts, Jan Diels, Jan Vanderborght, Jan Feyen, and Roel Merckx

The design of an inexpensive, easy-to-make, and reliable drop counter is presented. A linear relation between the number of drops and the applied flux was found, resulting in an average drop size of 35 microliters. The unique design of the drop counter results in small temperature and ionic strength effects of the leachate water on the drop volume.
Published online 14 April 2008; doi: 10.2136/vzj2007.0096
Vadose Zone J Apr 14 2008: 434–438 [Abstract] [Full Text] [PDF]  

SPECIAL SECTION: MULTISCALE MAPPINGBack

S. D. Logsdon, E. Perfect, and A. M. Tarquis
Multiscale Soil Investigations: Physical Concepts and Mathematical Techniques
The guest editors introduce the 12 articles featured in the special section. The contributions represent a range of highly original approaches for dealing with multiscale analysis of soil heterogeneity and cover a wide range of scales, from microns to kilometers.
Published online 27 May 2008; doi: 10.2136/vzj2007.0160
Vadose Zone J May 27 2008: 453–455 [Full Text] [PDF]  

Apostolos Papadopoulos, Nigel R. A. Bird, Sacha J. Mooney, and Andrew P. Whitmore

Soil pore surfaces provide sites for the biological, chemical, and physical processes within the soil. We used the slit island method to extract fractal dimensions of pore surface roughness from images of soil pore structure. We proposed additional analyses to test for constancy of pore shape and illustrated the application of the modified approach.
Published online 27 May 2008; doi: 10.2136/vzj2007.0017
Vadose Zone J May 27 2008: 456–460 [Abstract] [Full Text] [PDF]  

L. Aaron Blank, A. G. Hunt, and T. E. Skinner

Previous studies have compared analytical predictions from fractal models for water retention and hydraulic conductivities with experimental values. The present study produces also numerical predictions from experimental data, allowing more rigorous tests of fractal models.
Published online 27 May 2008; doi: 10.2136/vzj2007.0037
Vadose Zone J May 27 2008: 461–472 [Abstract] [Full Text] [PDF]  

S. A. Zamora-Castro, K. Oleschko, L. Flores, E. Ventura, Jr., and J. F. Parrot

A toolbox of reference fractal techniques was used for a comparative, multiscale and multitemporal analysis of the solid and pore network attribute dynamics. Contrasting media were compared during a long-term drying experiment under controlled conditions. The scale invariance of the pore and solid networks is documented statistically in time and space.
Published online 27 May 2008; doi: 10.2136/vzj2007.0020
Vadose Zone J May 27 2008: 473–492 [Abstract] [Full Text] [PDF]  

Guoping Tang, Edmund Perfect, Elmer H. van den Berg, Melanie A. Mayes, and Jack C. Parker

A monofractal model is introduced to describe the thickness-size distribution of layered sediments. Effective hydraulic properties are computed as a function of scale using a composite medium approximation. Model predictions for layered systems relevant to the USDOE's Hanford site are compared with numerical simulations.
Published online 27 May 2008; doi: 10.2136/vzj2007.0013
Vadose Zone J May 27 2008: 493–499 [Abstract] [Full Text] [PDF]  

E. Vidal Vázquez, J. Paz Ferreiro, J. G. V. Miranda, and A. Paz González

The spatial arrangement of soil pores determines soil structure and is important in modeling soil processes. The combination of Hg intrusion porosimetry and multifractal analysis gives insight into the differences between a recently worked soil surface and its degraded stage counterpart.
Published online 27 May 2008; doi: 10.2136/vzj2007.0011
Vadose Zone J May 27 2008: 500–511 [Abstract] [Full Text] [PDF]  

R. García Moreno, M. C. Díaz Álvarez, A. Saa Requejo, and A. M. Tarquis

We have developed a methodology for quantifying soil surface roughness based on multifractal analysis. The methodology compares the results to classical indices such as standard deviation, fractal dimension, and crossover length. Multifractal analysis appears to be better suited than these indices to compare plots tilled under different management criteria.
Published online 27 May 2008; doi: 10.2136/vzj2007.0016
Vadose Zone J May 27 2008: 512–520 [Abstract] [Full Text] [PDF]  

A. N. Kravchenko

A multifractal spectrum contains more information about spatial data variability than the traditional variogram. This study addressed the question, Can using multifractal characteristics in stochastic simulations instead of variograms lead to a better representation of spatial variability?
Published online 27 May 2008; doi: 10.2136/vzj2007.0009
Vadose Zone J May 27 2008: 521–524 [Abstract] [Full Text] [PDF]  

Qiuming Cheng

A new method has been developed for mapping spatial patterns by incorporating both scaling property and spatial association of spatial data. This multiscale mapping technique uses an integrated power-law model characterizing local singularity of exploratory data and moving average model for mapping surfaces with multifractality due to self-organization or self-similarity properties of the underlying processes. It was applied to map surface soil properties violating the assumption of statistical stationary property required by ordinary geostatistical mapping techniques.
Published online 27 May 2008; doi: 10.2136/vzj2007.0034
Vadose Zone J May 27 2008: 525–532 [Abstract] [Full Text] [PDF]  

S. Lovejoy, A. M. Tarquis, H. Gaonac'h, and D. Schertzer

In this paper scaling analysis and modeling techniques are applied to MODIS TERRA bands 1-7 and the standard derived vegetation and soil moisture indices to quantitatively characterize the wide range scaling of these fields using spectra, trace moments, structure functions and probability distribution multiple scaling (PDMS) methods. We show the need to develop resolution-independent algorithms based on the scaling exponents.
Published online 27 May 2008; doi: 10.2136/vzj2007.0173
Vadose Zone J May 27 2008: 533–546 [Abstract] [Full Text] [PDF]  

Bing Cheng Si

Understanding the scaling properties of soil spatial variability is important for managing natural resources and protecting our environment. Spectral and wavelet analyses were presented and illustrated using the soil hydraulic conductivity and other basic soil physical properties.
Published online 27 May 2008; doi: 10.2136/vzj2007.0040
Vadose Zone J May 27 2008: 547–562 [Abstract] [Full Text] [PDF]  

A. M. Tarquis, N. R. A. Bird, A. P. Whitmore, M. C. Cartagena, and Yakov Pachepsky

The object of this study was to describe the spatial scaling properties of a set of soil physical properties. The intrascale-dependent correlation functions between several variables (water content, total porosity, pH, and N2O flux) were performed from 1024-m transect scale to 8 m. These techniques allow research on scale effects localized in scale and provide the information that is complementary to the information about scale dependencies found across a range of scales.
Published online 27 May 2008; doi: 10.2136/vzj2007.0039
Vadose Zone J May 27 2008: 563–569 [Abstract] [Full Text] [PDF]  

Julie Earls and Barnali Dixon

The Soil and Water Assessment Tool (SWAT) is a mathematical model, freely distributed and integrated with geographic information systems. The SWAT estimates potential evapotranspiration (PET), a large but inaccurately quantified component in most water budgets. This study explored SWAT predictions of PET using three equations (Hargreaves, Penman-Monteith, and Priestley-Taylor) and multiple local meteorological sites vs. one national station.
Published online 27 May 2008; doi: 10.2136/vzj2007.0012
Vadose Zone J May 27 2008: 570–580 [Abstract] [Full Text] [PDF]  

SPECIAL SECTION: VADOSE ZONE MODELINGBack

Jirka Simunek and Scott A. Bradford
Vadose Zone Modeling: Introduction and Importance
This special issue documents the progress in modeling of vadose zone processes over the last three decades. Part 1 includes six papers that describe the latest developments or specific applications of some of the most widely used models. Part 2 includes 16 papers that describe modeling of specific vadose zone processes or associated applications.
Published online 27 May 2008; doi: 10.2136/vzj2008.0012
Vadose Zone J May 27 2008: 581–586 [Full Text] [PDF]  

Jirí Simunek, Martinus Th. van Genuchten, and Miroslav Sejna

We reviewed the background, development history, and selected applications of HYDRUS and related models and software developed collaboratively by groups in the United States, the Czech Republic, Israel, Belgium, and the Netherlands. Our main focus was on modeling tools developed jointly by the U.S. Salinity Laboratory and the University of California, Riverside.
Published online 27 May 2008; doi: 10.2136/vzj2007.0077
Vadose Zone J May 27 2008: 587–600 [Abstract] [Full Text] [PDF]  

S. Finsterle, C. Doughty, M.B. Kowalsky, G. J. Moridis, L. Pan, T. Xu, Y. Zhang, and K. Pruess

Advanced modeling capabilities of the TOUGH suite of multiphase flow and reactive transport simulators are used to capture the complexity of the vadose zone, and to understand and predict the intricate physical and biogeochemical processes determining its fate. Fundamental modeling challenges are discussed and solution approaches are presented.
Published online 27 May 2008; doi: 10.2136/vzj2007.0059
Vadose Zone J May 27 2008: 601–609 [Abstract] [Full Text] [PDF]  

Sorab Panday and Peter S. Huyakorn

Variations on the standard vadose zone flow and transport equations are discussed that allow for a wide variety of simulation capabilities as needed to analyze water resource issues or contamination sites from preliminary characterization to closure.
Published online 27 May 2008; doi: 10.2136/vzj2007.0052
Vadose Zone J May 27 2008: 610–631 [Abstract] [Full Text] [PDF]  

Richard W. Healy

The VS2DI graphical software package provides a user-friendly environment for simulating water, solute, and heat movement within the unsaturated zone. The model solves the Richards equation for water movement and the advection-dispersion equation for solute and heat transport. Its popularity relates to its ease of use, efficiency, and robustness.
Published online 27 May 2008; doi: 10.2136/vzj2007.0075
Vadose Zone J May 27 2008: 632–639 [Abstract] [Full Text] [PDF]  

Jos C. van Dam, Piet Groenendijk, Rob F.A. Hendriks, and Joop G. Kroes

Special features of the vadose zone transport model SWAP are generic crop growth, versatile top boundary conditions, macroporous flow and interaction of soil water with groundwater and surface water. Typical model applications and new model developments are discussed, and three case study applications are presented.
Published online 27 May 2008; doi: 10.2136/vzj2007.0060
Vadose Zone J May 27 2008: 640–653 [Abstract] [Full Text] [PDF]  

M. D. White, M. Oostrom, M. L. Rockhold, and M. Rosing

High-resolution numerical simulations conducted on supercomputers were applied to understand the fate of carbon tetrachloride, disposed into the deep vadose via trenches on the USDOE's Hanford Site. The STOMP simulations consider multifluid subsurface flow and transport, including nonaqueous phase liquid residual formation, hysteresis, and soil-vapor extraction.
Published online 27 May 2008; doi: 10.2136/vzj2007.0070
Vadose Zone J May 27 2008: 654–666 [Abstract] [Full Text] [PDF]  

Scott A. Bradford and Saeed Torkzaban

Simulating the transport and retention of colloids in the vadose zone is limited by our lack of basic understanding of colloid retention processes that occur at the interface, collector, and pore scales. Our current knowledge of physical and chemical mechanisms, factors, and models of colloid transport and retention at these scales is described.
Published online 27 May 2008; doi: 10.2136/vzj2007.0092
Vadose Zone J May 27 2008: 667–681 [Abstract] [Full Text] [PDF]  

Markus Flury and Hanxue Qiu

We describe modeling approaches for colloid-facilitated contaminant transport in the vadose zone. Conceptual models describing colloids interacting with solid-water and air-water interfaces are discussed, and the relevant mathematical formulations are presented.
Published online 27 May 2008; doi: 10.2136/vzj2007.0066
Vadose Zone J May 27 2008: 682–697 [Abstract] [Full Text] [PDF]  

D. Jacques, J. Simunek, D. Mallants, and M.Th. van Genuchten

This paper reviews interactions between physical and biogeochemical processes in the vadose zone. A simulation study investigates the effect of transient water flow on speciation, mobility, and sorption of Ca, P, and U during inorganic P fertilization. This is illustrated by the short-term variability of the linear distribution coefficient.
Published online 27 May 2008; doi: 10.2136/vzj2007.0084
Vadose Zone J May 27 2008: 698–711 [Abstract] [Full Text] [PDF]  

Krisztian Szegedi, Doris Vetterlein, Heino Nietfeld, Reinhold Jahn, and Heinz-Ulrich Neue

We have developed a new computer tool for modeling plant and soil processes based on coupling the mathematical package MATLAB with the geochemical code PHREEQC. The model takes into account all relevant processes for the transport and uptake of nutrients and contaminants. The model was verified using a benchmark problem and experimental data.
Published online 27 May 2008; doi: 10.2136/vzj2007.0064
Vadose Zone J May 27 2008: 712–720 [Abstract] [Full Text] [PDF]  

Holger Class, Rainer Helmig, and Insa Neuweiler

The characteristic processes in typical contaminant spreading and remediation scenarios in the unsaturated zone vary with different time scales or after an intervention in the system. Adapting the models to the specifically required complexity and coupling them sequentially is a good compromise between computational costs and accuracy of the results.
Published online 27 May 2008; doi: 10.2136/vzj2007.0056
Vadose Zone J May 27 2008: 721–731 [Abstract] [Full Text] [PDF]  

Rex A. Hodges and Ronald W. Falta

Steam flooding shallow vadose zone sites to remove VOC source zones can be problematic if the steam or contaminants vent to the surface. Cold air injection holds promise as a method for controlling vertical steam movement. A series of two-dimensional numerical simulations examine the sensitivity of this process to geological and operational parameters.
Published online 27 May 2008; doi: 10.2136/vzj2007.0093
Vadose Zone J May 27 2008: 732–740 [Abstract] [Full Text] [PDF]  

Alex Furman

This study identified three different coupling schemes, namely the uncoupled, the iteratively coupled, and the fully coupled. Applications of the different coupling schemes are reviewed. Research and engineering gaps are identified and discussed.
Published online 27 May 2008; doi: 10.2136/vzj2007.0065
Vadose Zone J May 27 2008: 741–756 [Abstract] [Full Text] [PDF]  

Navin Kumar C. Twarakavi, Jirka Simunek, and Sophia Seo

A comparative study of the currently available methods for the coupled modeling of vadose zone flow with the groundwater flow model MODFLOW is presented. The newly developed HYDRUS package is presented and compared with the VSF process and the UZF1 and REC-ET packages for different case studies at varying spatial and temporal scales.
Published online 27 May 2008; doi: 10.2136/vzj2007.0082
Vadose Zone J May 27 2008: 757–768 [Abstract] [Full Text] [PDF]  

Paul E. V. van Walsum and Piet Groenendijk

A fast unsaturated zone model has been developed for use in conjunction with a regional groundwater model. The algorithm dances around in a database of steady-state water content profiles. In a postprocessing stage, detailed information about the profiles is made available for use in agroecological evaluations and water quality simulations.
Published online 27 May 2008; doi: 10.2136/vzj2007.0146
Vadose Zone J May 27 2008: 769–781 [Abstract] [Full Text] [PDF]  

Jirka Simunek and Martinus Th. van Genuchten

We describe a wide range of nonequilibrium flow and transport approaches available within HYDRUS-1D. Formulations range from classical models simulating uniform flow and transport, to traditional mobile-immobile water physical and two-site chemical nonequilibrium models, to dual-permeability models considering physical and chemical nonequilibrium.
Published online 27 May 2008; doi: 10.2136/vzj2007.0074
Vadose Zone J May 27 2008: 782–797 [Abstract] [Full Text] [PDF]  

Radka Kodesová, Martin Kocárek, Vít Kodes, Jirí Simunek, and Josef Kozák

Micromorphological images were used for characterizing flow domains in three soil types. Dual-porosity and dual-permeability flow and transport models were applied for estimating multimodal soil hydraulic properties and for numerical simulation of herbicide transport within the soil profile that was experimentally studied in the field.
Published online 27 May 2008; doi: 10.2136/vzj2007.0079
Vadose Zone J May 27 2008: 798–809 [Abstract] [Full Text] [PDF]  

Blaine Hanson, Jan W. Hopmans, and Jirka Simunek

The historical water balance approach used to calculate leaching fractions frequently indicated little or no leaching in subsurface drip-irrigated commercial fields located in the salt-affected soil of the San Joaquin Valley even though soil salinity patterns around drip lines showed considerable leaching. The HYDRUS-2D computer model was used to determine leaching fractions with subsurface drip irrigation in these soils. Results showed that leaching fractions under subsurface drip irrigation ranged from 7.7 to 30.9% as applied water amounts increased from 60 to 115% of the potential evapotranspiration, indicating that the historical water balance approach is inappropriate for drip irrigation.
Published online 27 May 2008; doi: 10.2136/vzj2007.0053
Vadose Zone J May 27 2008: 810–818 [Abstract] [Full Text] [PDF]  

Julie Sansoulet, Yves-Marie Cabidoche, Philippe Cattan, Stéphane Ruy, and Jirka Simunek

Water fluxes in ecosystems vary spatially because of rainfall redistribution by the plant. Field lysimeters and tensiometers were used to quantify the spatial distribution of fluxes in the soil underlying a banana plant, simulated using the three-dimensional HYDRUS model. Due to the stemflow, drainage under the plant was up to six times higher than between the rows.
Published online 27 May 2008; doi: 10.2136/vzj2007.0073
Vadose Zone J May 27 2008: 819–829 [Abstract] [Full Text] [PDF]  

Günter Langergraber

Numerical models are valuable tools for gaining an understanding of processes that occur in constructed wetlands (CWs). In the first part of the paper, published mechanistic models for describing processes in subsurface flow CWs are reviewed. In the second part, one of these models, the multicomponent reactive transport module CW2D, is demonstrated.
Published online 27 May 2008; doi: 10.2136/vzj2007.0054
Vadose Zone J May 27 2008: 830–842 [Abstract] [Full Text] [PDF]  

Jasper A. Vrugt, Philip H. Stauffer, Th. Wöhling, Bruce A. Robinson, and Velimir V. Vesselinov

We review inverse modeling of flow and transport properties in vadose zone hydrology. We discuss the historical developments that led to current perspectives, and highlight our recent work at Los Alamos related to the development and implementation of improved optimization and data assimilation methods for computationally efficient calibration and uncertainty estimation in complex, distributed flow and transport models using parallel computing capabilities.
Published online 27 May 2008; doi: 10.2136/vzj2007.0078
Vadose Zone J May 27 2008: 843–864 [Abstract] [Full Text] [PDF]  

To see an article, click its [Full Text] link. To review many abstracts, check the boxes to the left of the titles you want, and click the 'Get All Checked Abstract(s)' button. To see one abstract at a time, click its [Abstract] link.

JOURNAL HOME HELP CONTACT PUBLISHER SUBSCRIBE ARCHIVE SEARCH TABLE OF CONTENTS
Copyright © 2008 by Soil Science Society of America