On the importance of hysteresis and heterogeneity in the numerical simulation of unsaturated flow

Nakagawa, Kei; Saito, Masahiko; Berndtsson, Ronny

doi:10.3178/hrl.6.59

Cited by 5 publications

(3 citation statements)

References 23 publications

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“…Based on these mechanisms, several models were developed to account for soil water retention hysteresis in the wet region (Kool & Parker, 1987;Pedroso & Williams, 2010;Rudiyanto et al, 2015;van Dam, Wösten, & Nemes, 1996;Zhuang, Bezerra Coelho, Hassanizadeh, & van Genuchten, 2017). Nakagawa, Saito, and Berndtsson (2012) noted that it is crucial to account for hysteresis in numerical models for unsaturated water flow.…”

Section: Introductionmentioning

confidence: 99%

Clay content and mineralogy, organic carbon and cation exchange capacity affect water vapour sorption hysteresis of soil

Arthur

Tuller

Møldrup

et al. 2019

European J Soil Science

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The hysteretic behaviour of the dry region (<−1.5 MPa) of the soil water characteristic, which is of the essence for accurate characterization and modelling of bio‐physicochemical soil processes under dry conditions, is well documented. However, knowledge about how to best quantify water vapour sorption hysteresis and about the effects of soil properties on dry‐region hysteretic behaviour is limited. To overcome this knowledge gap, we proposed a new method for quantifying sorption hysteresis and evaluated its applicability based on measured sorption isotherms of four source clay minerals and 147 soil samples. Furthermore, the effects of clay mineralogy, clay content, soil organic carbon (SOC) and cation exchange capacity (CEC) on the magnitude of sorption hysteresis were investigated. For the clay minerals, kaolinite did not exhibit hysteretic behaviour, illite showed some hysteresis, whereas Na‐ and Ca‐smectite exhibited strong hysteretic behaviour. The average hysteresis, corrected for clay and SOC contents, was strongly reflective of the dominant clay mineralogy of the soil samples. For the soil samples with low SOC content, the average hysteresis significantly increased with increasing clay content (R2 = 0.92), except for the kaolinite‐rich samples (R2 = 0.35). The SOC‐rich samples that exhibited illitic clay mineralogy and similar soil texture showed a significant increase in average hysteresis with increasing organic carbon content (R2 = 0.93). For all soil samples combined, the CEC was the strongest indicator for the magnitude of water vapour sorption hysteresis. Highlights A new index for quantification of soil vapour sorption hysteresis was proposed Large SOC and clay content increased sorption hysteresis For soil samples, dominant clay mineralogy controlled the magnitude of hysteresis Cation exchange capacity was the best predictor of hysteresis for all soil types

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Section: Introductionmentioning

confidence: 99%

Clay content and mineralogy, organic carbon and cation exchange capacity affect water vapour sorption hysteresis of soil

Arthur

Tuller

Møldrup

et al. 2019

European J Soil Science

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“…Modeling of physical and biological soil processes is more accurate when hysteresis of the SWC is considered, especially at low saturations where small differences in water contents cause large changes in potential energy (Prunty and Bell, 2007). Nakagawa et al (2012) reiterated the need to account for hysteresis in numerical models for both two‐phase and unsaturated water flows. Hysteresis of the SWC at low saturations for soils of varying texture has been previously considered only in a limited number of studies (Globus and Neusypina, 2006; Prunty and Bell, 2007; Davis et al, 2009; Arthur et al, 2013), most of which did not consider water retained below −20 MPa.…”

Section: Resultsmentioning

confidence: 99%

Rapid and Fully Automated Measurement of Water Vapor Sorption Isotherms: New Opportunities for Vadose Zone Research

Arthur

Tuller

Møldrup

et al. 2013

Vadose Zone Journal

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Eminent environmental challenges such as remediation of contaminated sites, the establishment and maintenance of nuclear waste repositories, or the design of surface landfill covers all require accurate quantification of the soil water characteristic (SWC) at low water contents. Furthermore, several essential but difficult‐to‐measure soil properties, including clay content and specific surface area, are intimately related to water vapor sorption. Until recently, it was a major challenge to measure detailed water vapor sorption isotherms accurately within a reasonable time frame. This priority communication illustrates potential applications of a new, fully automated, and rapid Vapor Sorption Analyzer (VSA) to pertinent issues in vadose zone research. Detailed vapor sorption isotherms for 25 variably textured soils were measured with the VSA within 1 to 3 d. Links between generated isotherms and pesticide volatilization, toxic organic vapor sorption kinetics, and soil water repellency are illustrated. Several methods to quantify hysteresis effects and to derive soil clay content and specific surface area from VSA‐measured isotherms are presented. Besides above mentioned applications, potential relationships to percolation threshold for solute diffusion in unsaturated soil and to soil cation exchange capacity are discussed to stimulate new and much‐needed vadose zone research.

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“…Natural soils and aquifers often possess very complex spatial patterns of hydraulic conductivity (Nakagawa et al, 2012;Zinn et al, 2004), leading to dispersive mixing of solutes. Solute dispersion is one of the key factors in understanding the fate and transport of solute contaminants within groundwater.…”

Section: Introductionmentioning

confidence: 99%

Experimental assessment of solute dispersion in stratified porous media

Kurasawa

Suzuki

Inoue

2020

Hydrological Research Letters

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The objective of this paper is to evaluate effects of stratified porous formation on solute dispersion using twodimensional laboratory tracer tests. An image analysis technique was used to analyze the solute dispersion processes and quantify the dispersivity and behaviors of forward and backward tails of solute plumes. Longitudinal dispersivity estimates for the stratified porous media increased with travel distance and are in reasonable agreement with previous work. Moreover, in all of the stratified cases the transverse dispersivity exhibited a similar trend which decayed with travel distance. The summary of dispersivities estimated from this study and previous studies suggests that if both degree of heterogeneity and scale for stratified and randomly heterogeneous porous media are similar, the longitudinal dispersivity is larger in stratified media than in randomly heterogeneous media. In order to quantify behaviors of forward and backward tails, we defined the travel distances x 05 and x 95 corresponding to the 5th and 95th percentiles, respectively, of the cumulative concentrations in the longitudinal direction, and found that the distance between x 05 and x 95 spread out linearly in the stratified cases. KEYWORDS solute dispersion; stratified porous media; laboratory-scale experiments; image analysis technique; dispersivity; solute plume tails

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On the importance of hysteresis and heterogeneity in the numerical simulation of unsaturated flow

Cited by 5 publications

References 23 publications

Clay content and mineralogy, organic carbon and cation exchange capacity affect water vapour sorption hysteresis of soil

Clay content and mineralogy, organic carbon and cation exchange capacity affect water vapour sorption hysteresis of soil

Rapid and Fully Automated Measurement of Water Vapor Sorption Isotherms: New Opportunities for Vadose Zone Research

Experimental assessment of solute dispersion in stratified porous media

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