Prediction of Hydraulic Conductivity as Related to Pore Size Distribution in Unsaturated Soils

Amer, Abdelmonem Mohamed; Logsdon, S. D.; Davis, Dedrick D.

doi:10.1097/ss.0b013e3181b76c29

Cited by 41 publications

(20 citation statements)

References 15 publications

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“…These models are described with the equations of Poiseuille and Darcy (Mualem 1976;Amer et al, 2009) in which water filled pores can be treated as capillary bundle tubes. The non-capillary pores have been recognized as significant pathways for water and solute movement in the soil.…”

Section: Introductionmentioning

confidence: 99%

Water flow and conductivity into capillary and non-capillary pores of soils

Amer

2012

J. Soil Sci. Plant Nutr.

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Downward water flow in the vadose zone occurs principally through the non-capillary pores, while the redistribution and lateral and upward flow occurs in the capillary pores. The purpose of this study was to propose equations to estimate water flow, Q(θ), and hydraulic conductivity, K(θ), in the capillary and non-capillary soil pores. The equations related K(θ) to soil pore radius (r) were based on soil hydraulic data, including water retention h(q), field basic infiltration rate, water sorptivity (S) and distribution density function f(r) of the soil pore size. Calcareous sandy loam and alluvial clay soils located at the Nile Delta were used to test the validity of the assumed equations. Data showed that the values of K(θ) calculated by the proposed equations were in the common ranges for such soils. The equations are therefore expected to be applicable for both coarse and fine textured soils. Also, an equation was derived to estimate the sorptivity at steady state infiltration. It was observed that S is decreased in going from the un-saturation condition to steady state infiltration by 15.1% and 45.9% in sandy loam and clay soils, respectively.

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Section: Introductionmentioning

confidence: 99%

Water flow and conductivity into capillary and non-capillary pores of soils

Amer

2012

J. Soil Sci. Plant Nutr.

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“…Mean values of pore size classes expressed as percent of soil water volume relative to total bulk volume (Dy%), and relative to the volume of pores (Dy/y s in Shebin El-Kom clay soil (profile III). The alluvial clay profiles (III and V) had considerable swelling as do most alluvial soils in the Nile Delta (Amer et al 2009). The swelling, high clay content and high salinity contributed to these trends.…”

Section: Distribution Of Pore Size Classes In Soilsmentioning

confidence: 97%

“…The soil pores were classified into rapidly drainable non-capillary pores (RDP; 0-10 kPa) and matrix capillary pores, which were subdivided into slowly drainable pores (SDP; 10-33 kPa), water-holding pores (WHP; 33-1500 kPa) and fine capillary pores (FCP; 41500 kPa) by Amer (2011). Because defined ranges of non-capillary (macro) pore size are vary widely from 530 mm (h 4 10 kPa) to 43000 mm (h 5 0.1 kPa) (Beven and Germann 1982), the pressure head h ¼ 10 kPa was specified as a limit between non-capillary RDP and soil matrix capillary pores (Marshall 1956;Amer et al 2009). In most cases, non-capillary (macro) pores comprise only a small portion of the total soil porosity, but under some conditions vertical flow rates may dominate during infiltration (Chen and Wagenet 1992).…”

Section: Introductionmentioning

confidence: 99%

Prediction of hydraulic conductivity and sorptivity in soils at steady-state infiltration

Amer

2012

Archives of Agronomy and Soil Science

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The purpose of this study was (1) to find a matching factor (u) between infiltration rate and hydraulic conductivity during steady-state infiltration, and (2) to propose equations based on infiltration and soil moisture-retention functions for prediction of the hydraulic conductivity K(y) within the rapidly (non-capillary) drainable pores (RDP) and capillary-matrix pores of soils. The K(y) of capillary pores was divided into K(y) SDP , K(y) WHP and K(y) FCP within slowly drainable pores (SDP), water-holding pores (WHP) and fine capillary pores (FCP), respectively. Five soil profiles of calcareous sandy loam, alluvial saline and non-saline clay, located at the Nile Delta, were used to apply the proposed equations. The highest and the lowest values of K(y) RDP were observed in calcareous and saline clay soil profiles, respectively. Values of K(y) RDP remained higher than those for capillary pores in the studied soils. The predicted values of K(y) in capillary and non-capillary pores classes were in the expected range for unsaturated hydraulic conductivity. Water sorptivity (S) was determined at initial unsaturated soil water conditions and calculated at steady-state infiltration (S w ) using a derived equation. There was a decrease in S with an increase in soil water content; i.e. at steady-state infiltration, S decreased by 35-40% in calcareous soils and by 45-60% in alluvial clay soils. The parameter values of u and S w tended to be uniform in calcareous soils, but nonuniform in saline and non-saline clay soils.

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“…Research Article promote hydraulic conductivity 23 and are necessary for PRBs to function effectively. Some pores observed in BC-ZVI may be continuous and allow for intraparticle transport, but interparticle pore size can be designed by particle sizing.…”

Section: Acs Sustainable Chemistry and Engineeringmentioning

confidence: 99%

Macroporous Carbon Supported Zerovalent Iron for Remediation of Trichloroethylene

Lawrinenko

Wang

Horton

et al. 2017

ACS Sustainable Chem. Eng.

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Groundwater contamination with chlorinated hydrocarbons has become a widespread problem that threatens water quality and human health. Permeable reactive barriers (PRBs), which employ zerovalent iron, are effective for remediation; however, a need exists to reduce the economic and environmental costs associated with constructing PRBs. We present a method to produce zerovalent iron supported on macroporous carbon using only lignin and magnetite. Biochar-ZVI (BC-ZVI) produced by this method exhibits a broad pore size distribution with micrometer sized ZVI phases dispersed throughout a carbon matrix. X-ray diffraction revealed that pyrolysis at 900 °C of a 50/50 lignin–magnetite mixture resulted in almost complete reduction of magnetite to ZVI and that compression molding promotes iron reduction in pyrolysis due to mixing of starting materials. High temperature pyrolysis of lignin yields some graphite in BC-ZVI due to reduction of carbonaceous gases on iron oxides. TCE was removed from water as it passed through a column packed with BC-ZVI at flow rates representative of average and high groundwater flow. One-dimensional convection–dispersion modeling revealed that adsorption by biochar influences TCE transport and that BC-ZVI facilitated removal of TCE from contaminated water by both adsorption and degradation.

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Prediction of Hydraulic Conductivity as Related to Pore Size Distribution in Unsaturated Soils

Cited by 41 publications

References 15 publications

Water flow and conductivity into capillary and non-capillary pores of soils

Water flow and conductivity into capillary and non-capillary pores of soils

Prediction of hydraulic conductivity and sorptivity in soils at steady-state infiltration

Macroporous Carbon Supported Zerovalent Iron for Remediation of Trichloroethylene

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