Bimodal Porosity and Unsaturated Hydraulic Conductivity

Othmer, Heinrich; Diekkrüger, Bernd; Kutílek, Miroslav

doi:10.1097/00010694-199109000-00001

Cited by 154 publications

(101 citation statements)

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“…Variably saturated water flow through such a porous system is uniform and at local equilibrium, and is often described using the Richards equation. Bimodal or multimodal hydraulic functions (e.g., Othmer et al, 1991;Wilson et al, 1992;Ross and Smettem, 1993;Durner, 1994;Mohanty et al, 1997) are an indirect way of representing soil structure in such a uniform flow approach. A one-domain PNE concept of infiltration (Fig.…”

Section: Conceptual Modelsmentioning

confidence: 99%

“…Parameter fitting of retention and hydraulic conductivity measurements on soil cores (Othmer et al, 1991;Ross and Smettem, 1993;Durner, 1994;Coppola, 2000;Köhne et al, 2002b, Priesack andDurner, 2006) UC θ(h) and K(h) of fractured porous media Upscaling of modelled liquid configurations of cross-sections of partially saturated fractured porous soil or rock (Tuller and Or, 2002;Or and Tuller, 2003) UC Moreover, it was suggested to direct more effort to derive pedotransfer functions accounting for soil structure effects (Merdun and Quisenberry, 2004;Pachepsky et al, 2006). The relation between lateral dispersivity, unsaturated hydraulic conductivity, and soil morphological properties, was studied in tracer experiments carried out in columns and field plots with key Belgian soil types (Vanderborght et al, 2001).…”

Section: Column Experiments and Pedotransfer Functionsmentioning

confidence: 99%

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A review of model applications for structured soils: a) Water flow and tracer transport

Köhne

Šimůnek

2009

Journal of Contaminant Hydrology

292

224

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Section: Conceptual Modelsmentioning

confidence: 99%

Section: Column Experiments and Pedotransfer Functionsmentioning

confidence: 99%

A review of model applications for structured soils: a) Water flow and tracer transport

Köhne

Šimůnek

2009

Journal of Contaminant Hydrology

292

224

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“…The theory was tested on data sets of soil water retention and of unsaturated hydraulic conductivity catalogued in the UNSODA data base (Leij et al 1996;and Nemes et al 1999) and on the data sets published by Othmer et al (1991). We selected soils texturally comparable where the swelling/shrinkage processes are negligible on the macroscale (silt loam and loam) and in addition to them we included into the study sandy soils, too.…”

Section: Materials and Methods Experimental Data Setsmentioning

confidence: 99%

“…(8) is valid even for n-modal soils, n > 2. With the principle of superposition, applied already by Othmer et al (1991), Pachepsky et al (1992) and by Zeiliguer (1992) we define for bi-modal soils θ = θ 1 + θ 2 (10)…”

Section: S10mentioning

confidence: 99%

“…(7) shows a strong dependence of K R upon the soil water retention function. We find Soil & Water Res., 3, 2008 (Special Issue 1): S7-S20 frequently (Othmer et al 1991;Durner 1992) two or even three peaks on the derivative curve to the soil water retention curve ( Figure 1) and then we speak on bi-modal or tri-modal pore size distribution, or briefly on bi-or tri-modal soils. The direct experimental proof on existence of soil bi-modality is in publications on micromorphology (Pagliai & Vignozzi 2002) and in evaluation of the pore size distribution in water filled pores by nuclear magnetic resonance (Bird et al 2005).…”

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confidence: 99%

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The structural porosity in soil hydraulic functions - a review

Kutílek¹,

Jendele²

2008

Soil & Water Res.

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Products of biological processes are the dominant factor of soil structure formation in A horizons, while in B horizons their role is less expressed. Soil structure influences dominantly the structural domain of the pore system in bimodal soils thus affecting soil hydraulic functions. The form of soil hydraulic functions depends upon the pore size distribution and generally upon configuration of the soil pore system. We used the functions derived for the lognormal pore size distribution and modified them to bi-modal soils. The derived equations were tested by experimental data of catalogued soils. The procedure leads to the separation of two mutually different domains of structural and matrix pores. The value of the pressure head (potential) separating the two domains is not constant and varies in a broad range. For each domain we obtained its water retention function and unsaturated hydraulic conductivity function. The separation of hydraulic functions for the two domains is a key problem in the solution of preferential flow and in controlling lateral flow between the structural and matrix domains. Water retention function is fully physically based while the conductivity function still keeps fitting parameters, too. Their simple relationship to tortuosity and pores connectivity was not confirmed. Since they differ substantially for matrix and structural domains, we suppose that there exists a great difference in configuration of porous systems in structural and matrix domains. The use of uniform fitting conductivity parameters for the whole range of pores is not justifiable.

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Measurement and simulation of herbicide transport in macroporous soils

1998

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Lysimeter experiments were carried out to study pesticide transport through macroporous soils. In order to differentiate between the effects of soil structure and chemical behaviour, the leaching experiments were conducted using disturbed and undisturbed soil samples. Two herbicides with different sorption behaviours, and bromide as tracer were applied. The results were used to validate a dynamic simulation model which considers bypass flow in macropores. The simulation results show that the model is able to reproduce the soil suction within the soil as well as the spatial distribution of bromide and the herbicides. The continuity of the macropores is most important for the efficiency of bypass flow. The results indicate that cultivation practices like ploughing significantly influence the temporal and spatial distribution of the macropores. © 1998 SCI.

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Bimodal Porosity and Unsaturated Hydraulic Conductivity

Cited by 154 publications

References 0 publications

A review of model applications for structured soils: a) Water flow and tracer transport

A review of model applications for structured soils: a) Water flow and tracer transport

The structural porosity in soil hydraulic functions - a review

Measurement and simulation of herbicide transport in macroporous soils

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