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  • 1
    Language: English
    In: Journal of Hydrology, October 2015, Vol.529, pp.1277-1281
    Description: To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.jhydrol.2015.09.019 Byline: Morteza Sadeghi, Markus Tuller, Mohammad R. Gohardoust, Scott B. Jones Article Note: (miscellaneous) This manuscript was handled by Peter K. Kitanidis, Editor-in-Chief, with the assistance of J.A. Huisman, Associate Editor
    Keywords: Geography
    ISSN: 0022-1694
    E-ISSN: 1879-2707
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  • 2
    Language: English
    In: Journal of Hydrology, Nov 27, 2014, Vol.519, p.1238(11)
    Description: To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.jhydrol.2014.09.004 Byline: Morteza Sadeghi, Markus Tuller, Mohammad R. Gohardoust, Scott B. Jones Abstract: acents A new solution for steady-state evaporation from coarse-textured porous media is presented. acents The solution is not restricted to a specific form of the unsaturated hydraulic conductivity function. acents The solution offers an alternative method for determination of unsaturated hydraulic conductivity. acents Based on this theory, "effective" hydraulic properties of layered soils can be estimated. Article History: Received 6 July 2014; Revised 29 August 2014; Accepted 2 September 2014 Article Note: (miscellaneous) This manuscript was handled by Peter K. Kitanidis, Editor-in-Chief, with the assistance of J.A. Huisman, Associate Editor
    Keywords: Hydrogeology ; Soils
    ISSN: 0022-1694
    Source: Cengage Learning, Inc.
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  • 3
    Language: English
    In: Journal of Hydrology, Oct 10, 2013, Vol.502, p.120(8)
    Description: To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.jhydrol.2013.08.031 Byline: T.K.K. Chamindu Deepagoda, Jose Choc Chen Lopez, Per Moldrup, Lis Wollesen de Jonge, Markus Tuller Abstract: acents Water and oxygen availability for soilless plant growth substrates were determined. acents Integral water storage and energy concepts were expanded to dual-porosity media. acents An analog integral oxygen diffusivity parameter was introduced. Article History: Received 28 June 2013; Revised 13 August 2013; Accepted 21 August 2013 Article Note: (miscellaneous) This manuscript was handled by Peter K. Kitanidis, Editor-in-Chief, with the assistance of J. A imA[macron]nek, Associate Editor
    ISSN: 0022-1694
    Source: Cengage Learning, Inc.
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  • 4
    Language: English
    In: Journal of Hydrology, 27 November 2014, Vol.519, pp.1238-1248
    Description: Steady-state evaporation from a water table has been extensively studied for both homogeneous and layered porous media. For layered media it is of interest to find an equivalent homogeneous medium and define “effective” hydraulic properties. In this paper a new solution for steady-state evaporation from coarse-textured porous media is presented. Based on this solution, the evaporation rate represents a macroscopic (column-scale) measure of unsaturated hydraulic conductivity at the pressure head equal to the maximum extent of the hydraulically connected region above the water table. The presented approach offers an alternative method for determination of unsaturated hydraulic conductivity of homogeneous coarse-textured soils and a new solution for prediction of the effective unsaturated hydraulic conductivity of layered coarse-textured soils. The solution was evaluated with both experimental data and numerical simulations. Comparison with experimental data and numerical results for hypothetically layered soil profiles demonstrate the applicability of the proposed approach for coarse-textured soils.
    Keywords: Steady-State Evaporation ; Unsaturated Hydraulic Conductivity ; Heterogeneity ; Upscaling ; Effective Hydraulic Properties ; Geography
    ISSN: 0022-1694
    E-ISSN: 1879-2707
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  • 5
    Language: English
    In: Journal of Hydrology, 2015, Vol.521, p.498(10)
    Description: To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.jhydrol.2014.12.018 Byline: Dan Karup Jensen, Markus Tuller, Lis W. de Jonge, Emmanuel Arthur, Per Moldrup Abstract: * We present a new approach to predict the entire SWC using limited data. * The approach considers capillarity and adsorptive contributions to obtain the SWC. * We obtained accurate prediction of SWC regardless of soil texture. * Clay, silt and organic matter contribute significantly to water adsorption. Article History: Received 23 July 2014; Revised 10 December 2014; Accepted 11 December 2014 Article Note: (miscellaneous) This manuscript was handled by Peter K. Kitanidis, Editor-in-Chief, with the assistance of J. Simunek, Associate Editor
    Keywords: Soil Moisture
    ISSN: 0022-1694
    Source: Cengage Learning, Inc.
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  • 6
    Language: English
    In: Journal of Hydrology, March 2017, Vol.546, pp.81-89
    Description: For simulating flow in heterogeneous porous media it is computationally more efficient to define an equivalent effective (i.e., upscaled) medium rather than considering detailed spatial heterogeneities. In this paper, the effective unsaturated hydraulic conductivity ( ) of soils exhibiting random variability, layering, or both is calculated based on numerical simulations of steady-state evaporation from a shallow water table. It is demonstrated that the effective of randomly-varied coarse-textured soils generally falls between the harmonic and geometric means of the unsaturated hydraulic conductivities of the constituting soils. Layering and random variability when occurring concurrently magnify each other’s effects on effective . As a result, the higher the degree of heterogeneity, the lower the effective . Therefore, neglecting either random spatial variability or layering in numerical simulations can lead to significant overestimation of water flow in soils.
    Keywords: Upscaling ; Effective Unsaturated Hydraulic Conductivity ; Steady State Evaporation ; Soil Layering ; Random Variability ; Geography
    ISSN: 0022-1694
    E-ISSN: 1879-2707
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  • 7
    Language: English
    In: Journal of Hydrology, February 2015, Vol.521, pp.498-507
    Description: The present study proposes a new two-step approach to prediction of the continuous soil water characteristic (SWC) from saturation to oven-dryness from a limited number of measured textural data, organic matter content and dry bulk density. The approach combines dry- and wet-region functions to obtain the entire SWC by means of parameterizing a previously developed continuous equation. The dry region function relates gravimetric soil fractions to adsorptive forces and the corresponding water adsorbed to soil particles. The wet region function converts the volumetric particle size fractions to pore size fractions and utilizes the capillary rise equation to predict water content and matric potential pairs. Twenty-one Arizona source soils with clay and organic carbon contents ranging from 0.01 to 0.52 kg kg and 0 to 0.07 kg kg , respectively, were used for the model development. The SWCs were measured with Tempe cells, a WP4-T Dewpoint Potentiameter, and a water vapor sorption analyzer (VSA). The model was subsequently tested for eight soils from various agricultural fields in Denmark with clay contents ranging from 0.05 to 0.41 kg kg . Test results clearly revealed that the proposed model can adequately predict the SWC based on limited soil data. The advantage of the new model is that it considers both capillary and adsorptive contributions to obtain the SWC from saturation to oven-dryness.
    Keywords: Capillarity ; Adsorption ; Unsaturated Soil ; Water Retention ; Soil Moisture ; Geography
    ISSN: 0022-1694
    E-ISSN: 1879-2707
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  • 8
    Language: English
    In: Journal of Hydrology, 10 October 2013, Vol.502, pp.120-127
    Description: Over the last decade there has been a significant shift in global agricultural practice. Because the rapid increase of human population poses unprecedented challenges to production of an adequate and economically feasible food supply for undernourished populations, soilless greenhouse production systems are regaining increased worldwide attention. The optimal control of water availability and aeration is an essential prerequisite to successfully operate plant growth systems with soilless substrates such as aggregated foamed glass, perlite, rockwool, coconut coir, or mixtures thereof. While there are considerable empirical and theoretical efforts devoted to characterize water retention and aeration substrate properties, a holistic, physically-based approach considering water retention and aeration concurrently is lacking. In this study, the previously developed concept of integral water storage and energy was expanded to dual-porosity substrates and an analog integral oxygen diffusivity parameter was introduced to simultaneously characterize aeration properties of four common soilless greenhouse growth media. Integral parameters were derived for greenhouse crops in general, as well as for tomatoes. The integral approach provided important insights for irrigation management and for potential optimization of substrate properties. Furthermore, an observed relationship between the integral parameters for water availability and oxygen diffusivity can be potentially applied for the design of advanced irrigation and management strategies to ensure stress-free growth conditions, while conserving water resources.
    Keywords: Soilless Plant Growth Substrates ; Plant Available Water ; Substrate Water Characteristic ; Integral Water Storage ; Integral Energy ; Integral Oxygen Diffusivity ; Geography
    ISSN: 0022-1694
    E-ISSN: 1879-2707
    Source: ScienceDirect Journals (Elsevier)
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  • 9
    Language: English
    In: Journal of Hydrology, 06 May 2014, Vol.512, pp.388-396
    Description: The saturated hydraulic conductivity ( ) is an essential effective parameter for the development of improved distributed hydrological models and area-differentiated risk assessment of chemical leaching. Basic soil properties such as the particle size distribution or, more recently, air permeability are commonly used to estimate . Conversely, links to soil gas diffusivity ( / ) have not been fully explored even though gas diffusivity is intimately linked to the connectivity and tortuosity of the soil pore network. Based on measurements for a coarse sandy soil, potential relationships between and / were investigated. A total of 84 undisturbed soil cores were extracted from the topsoil of a field site, and / and were measured in the laboratory. Water-induced and solids-induced tortuosity factors were obtained by applying a two-parameter / model to measured data, and subsequently linked to the cementation exponent of the well-established Revil and Cathles predictive model for saturated hydraulic conductivity. Furthermore, a two-parameter model, analogue to the Kozeny–Carman equation, was developed for the − / relationship. All analyses implied strong and fundamental relationships between and / .
    Keywords: Soil Gas Diffusivity ; Tortuosity ; Saturated Hydraulic Conductivity ; Porosity ; Particle Size Distribution ; Geography
    ISSN: 0022-1694
    E-ISSN: 1879-2707
    Source: ScienceDirect Journals (Elsevier)
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  • 10
    Language: English
    In: Journal of Contaminant Hydrology, 2011, Vol.126(1), pp.100-112
    Description: The shrink-swell behavior of active clays in response to changes in physicochemical conditions creates great challenges for construction of geotechnical barriers for hazardous waste isolation, and is of significant importance for management of agricultural and natural resources. Initiation and evolution of desiccation cracks in active clays are strongly dependent on physicochemical initial and boundary conditions. To investigate effects of bentonite content (20, 40, 60%), pore fluid chemistry (0.05 and 0.5 M NaCl) and drying rates (40 and 60 °C) on cracking behavior, well-controlled dehydration experiments were conducted and X-ray Computed Tomography (CT) was applied to visualize and quantify geometrical features of evolving crack networks. A stochastic model based on the Fokker-Plank equation was adopted to describe the evolution of crack aperture distributions (CAD) and to assess the impact of physicochemical factors on cracking behavior. Analyses of crack porosity and crack specific surface area showed that both clay content and temperature had larger impact on cracking than pore fluid concentration. More cracks formed at high bentonite contents (40 and 60%) and at high drying rate (60 °C). The drift, diffusion and source terms derived from stochastic analysis indicated that evaporative demand had greater influence on the dynamics of the CAD than solution chemistry.
    Keywords: Bentonite Barriers ; Desiccation Cracks ; Physicochemical Conditions ; X-Ray Computed Tomography ; Stochastic Modeling ; Fokker-Plank Equation ; Engineering ; Environmental Sciences ; Geography
    ISSN: 0169-7722
    E-ISSN: 1873-6009
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