Models of the water retention curve for soils with a fractal pore size distribution

In highly porous soils with a susceptibility to collapse, there are points of volumetric variability, due to the present heterogeneity, regarding the diameters of the poral throat. The predominance of a pore size is closely related to certain values of the Water Retention Curve (WRC). However, to date, a possible correlation with particle size distribution (PaSD), obtained using modern, highly reliable gravitational sedimentation methods, has not been studied. The porous clay of lateritic origin under study, was characterized by means of index tests, to know its basic geotechnical behavior. Subsequently, it was analyzed by mercury intrusion porosimetry tests, to estimate the Pore Size Distribution (PSD); filter paper and pressure plate method to obtain the water retention curve; as well as the method of integral measurement of the pressure in the suspension (ISP), to obtain the fine grain size of the material. This article tries to present a proposal of relationship between these parameters, with the aim of improving the understanding in the characterization of this type of materials. The results showed that there is indeed a strong relationship between the particle size distributions, pore size distribution and the water retention curve. Mainly, this is reflected in the geometric places corresponding to the air value entries (AEV) of macropores and micropores. Which coincide with essential parameters of the behavior of the other curves (PaSD and PSD).

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Accounting for evolving pore size distribution in water retention models for compacted clays

International Journal for Numerical and Analytical Methods in Geomechanics ◽

10.1002/nag.2326 ◽

2014 ◽

Vol 39 (7) ◽

pp. 702-723 ◽

Cited By ~ 32

Author(s):

Gabriele Della Vecchia ◽

Anne-Catherine Dieudonné ◽

Cristina Jommi ◽

Robert Charlier

Keyword(s):

Pore Size Distribution ◽

Pore Size ◽

Size Distribution ◽

Water Retention ◽

Retention Models ◽

Compacted Clays

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Prediction of soil water retention properties using pore-size distribution and porosity

Canadian Geotechnical Journal ◽

10.1139/cgj-2012-0320 ◽

2013 ◽

Vol 50 (4) ◽

pp. 435-450 ◽

Cited By ~ 25

Author(s):

Christopher T.S. Beckett ◽

Charles E. Augarde

Keyword(s):

Pore Size Distribution ◽

Pore Size ◽

Size Distribution ◽

Soil Water ◽

Water Retention ◽

Adsorbed Water ◽

Retention Data ◽

Soil Water Retention ◽

Pore Size Distributions ◽

Water Retention Properties

Several models have been suggested to link a soil's pore-size distribution to its retention properties. This paper presents a method that builds on previous techniques by incorporating porosity and particles of different sizes, shapes, and separation distances to predict soil water retention properties. Mechanisms are suggested for the determination of both the main drying and wetting paths, which incorporate an adsorbed water phase and retention hysteresis. Predicted results are then compared with measured retention data to validate the model and to provide a foundation for discussing the validity and limitations of using pore-size distributions to predict retention properties.

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Predicting water retention curves of fine texture soils from particle size distribution

10.5194/egusphere-egu2020-6958 ◽

2020 ◽

Author(s):

Joseph Pollacco ◽

Jesús Fernández-Gálvez ◽

Sam Carrick

Keyword(s):

Particle Size ◽

Particle Size Distribution ◽

Size Distribution ◽

Hydraulic Properties ◽

Water Retention ◽

Pore Space ◽

Water Retention Curve ◽

Soil Hydraulic Properties ◽

Retention Curve ◽

Soil Particles

Indirect methods for estimating soil hydraulic properties from particle size distribution have been developed due to the difficulty in accurately determining soil hydraulic properties, and the fact that particle size distribution is one piece of basic soil physical information normally available. The similarity of the functions describing the cumulative distribution of particle size and pore size in the soil has been the basis for relating particle size distribution and the water retention function in the soil. Empirical and semi-physical models have been proposed, but these are based on strong assumptions that are not always valid. For example, soil particles are normally assumed to be spherical, with constant density regardless of their size; and the soil pore space has been described by an assembly of capillary tubes, or the pore space in the soil matrix is assumed to be arranged in a similar way regardless of particle size. However, in a natural soil the geometry of the pores may vary with the size of the particles, leading to a variable relation between particle radius and pore radius.&#160;The current work is based on the hypothesis that the geometry of the pore size and the void ratio depends on the size of the soil particles, and that a physically based model can be generalised to predict the water retention curve from particle size distribution. The rearrangement of the soil particles is considered by introducing a mixing function that modulates the cumulative particle size distribution, while the total porosity is constrained by the saturated water content.&#160;The model performance is evaluated by comparing the soil water retention curve derived from laboratory measurements with a mean Nash&#8211;Sutcliffe model efficiency a value of 0.92 and a standard deviation of 0.08. The model is valid for all soil types, not just those with a marginal clay fraction.

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Water Retention and Pore Size Distribution of a Biopolymeric-Amended Loam Soil

Vadose Zone Journal ◽

10.2136/vzj201811.0205 ◽

2019 ◽

Vol 18 (1) ◽

pp. 0 ◽

Cited By ~ 1

Author(s):

Mehdi Rahmati ◽

Andreas Pohlmeier ◽

Sara Mola Ali Abasiyan ◽

Lutz Weihermüller ◽

Harry Vereecken

Keyword(s):

Pore Size Distribution ◽

Pore Size ◽

Size Distribution ◽

Water Retention ◽

Loam Soil

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Physical parameters of Fluvisols on flooded and non-flooded terraces

International Agrophysics ◽

10.1515/intag-2016-0026 ◽

2017 ◽

Vol 31 (1) ◽

pp. 73-82 ◽

Cited By ~ 3

Author(s):

Milena Kercheva ◽

Zofia Sokołowska ◽

Mieczysław Hajnos ◽

Kamil Skic ◽

Toma Shishkov

Keyword(s):

Pore Size Distribution ◽

Pore Size ◽

Size Distribution ◽

Mercury Intrusion Porosimetry ◽

Water Retention Curve ◽

Anthropogenic Factors ◽

Physical Parameters ◽

Water Desorption ◽

Mercury Intrusion ◽

The Impact

Abstract The heterogeneity of soil physical properties of Fluvisols, lack of large pristine areas, and different moisture regimes on non-flooded and flooded terraces impede the possibility to find a soil profile which can serve as a baseline for estimating the impact of natural or anthropogenic factors on soil evolution. The aim of this study is to compare the pore size distribution of pristine Fluvisols on flooded and non-flooded terraces using the method of the soil water retention curve, mercury intrusion porosimetry, nitrogen adsorption isotherms, and water vapour sorption. The pore size distribution of humic horizons of pristine Fluvisols on the non-flooded terrace differs from pore size distribution of Fluvisols on the flooded terrace. The peaks of textural and structural pores are higher in the humic horizons under more humid conditions. The structural characteristics of subsoil horizons depend on soil texture and evolution stage. The peaks of textural pores at about 1 mm diminish with lowering of the soil organic content. Structureless horizons are characterized by uni-modal pore size distribution. Although the content of structural pores of the subsoil horizons of Fluvisols on the non-flooded terrace is low, these pores are represented by biopores, as the coefficient of filtration is moderately high. The difference between non-flooded and flooded profiles is well expressed by the available water storage, volume and mean radius of pores, obtained by mercury intrusion porosimetry and water desorption, which are higher in the surface horizons of frequently flooded Fluvisols.

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Hydraulic Properties of Forest Soils with Stagnic Conditions

Forests ◽

10.3390/f12081113 ◽

2021 ◽

Vol 12 (8) ◽

pp. 1113

Author(s):

Stefan Julich ◽

Janis Kreiselmeier ◽

Simon Scheibler ◽

Rainer Petzold ◽

Kai Schwärzel ◽

...

Keyword(s):

Pore Size Distribution ◽

Pore Size ◽

Size Distribution ◽

Hydraulic Properties ◽

Water Retention ◽

Soil Samples ◽

Stagnant Water ◽

Infiltration Rates ◽

Retention Characteristic ◽

Water Conditions

Tree species, e.g., shallow vs. deep rooting tree species, have a distinct impact on hydrological properties and pore size distribution of soils. In our study, we determined the soil hydrologic properties and pore size distribution at three forest stands and one pasture as reference on soils with stagnant water conditions. All sites are located in the Wermsdorf Forest, where historical studies have demonstrated severe silvicultural problems associated with stagnant water in the soil. The studied stands represent different stages of forest management with a young 25-year-old oak (Sessile Oak (Quercus petraea) and Red oak (Q. robur)) plantation, a 170-year-old oak stand and a 95-year-old Norway Spruce (Picea abies) stand in second rotation. We determined the infiltration rates under saturated and near-saturated conditions with a hood-infiltrometer at the topsoil as well as the saturated hydraulic conductivity and water retention characteristic from undisturbed soil samples taken from the surface and 30 cm depth. We used the bi-modal Kosugi function to calculate the water retention characteristic and applied the normalized Young-Laplace equation to determine the pore size distribution of the soil samples. Our results show that the soils of the old stands have higher amounts of transmission pores, which lead to higher infiltration rates and conductance of water into the subsoil. Moreover, the air capacity under the old oak was highest at the surface and at 30 cm depth. There was also an observable difference between the spruce and oak regarding their contrasting root system architecture. Under the oak, higher hydraulic conductivities and air capacities were observed, which may indicate a higher and wider connected macropore system. Our results confirm other findings that higher infiltration rates due to higher abundance of macropores can be found in older forest stands. Our results also demonstrate that an adapted forest management is important, especially at sites affected by stagnant water conditions. However, more measurements are needed to expand the existing data base of soil hydraulic properties of forest soils in temperate climates.

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