Evaluation and application of the modified van Genuchten function for unsaturated porous media

Luo, Zhaoyang; Kong, Jun; Shen, Chengji; Lu, Chunhui; Ge, Hua; Zhao, Zhimiao; Zhao, Hongjun; Li, Ling

doi:10.1016/j.jhydrol.2019.01.051

Cited by 19 publications

(12 citation statements)

References 41 publications

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“…consistent with those of Ren et al (2016), who also adopted the V-G and Feddes models to portray soil water dynamics. The most influential parameter was a coefficient of the V-G equation, confirming the importance of soil hydraulic functions in soil moisture modeling (Vereecken et al, 2010;Luo et al, 2019).…”

Section: Discussionmentioning

confidence: 54%

Soil hydrothermal modeling in a dry alpine agricultural zone: The effect of soil airflow

et al. 2021

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Section: Discussionmentioning

confidence: 54%

Soil hydrothermal modeling in a dry alpine agricultural zone: The effect of soil airflow

et al. 2021

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“…In light of this criterion, Kong et al (2016) successfully used an RHC expression that has the same functional form but different parameters as the WRC expression of Troch (1993). Subsequently, Luo et al (2019) evaluated this RHC expression by comparing it with commonly used RHC expressions, tested with a data set including a wide range of soil types, from sand to clay. Their results showed that the RHC expression of Kong et al (2016) performed best overall.…”

Section: Methodsmentioning

confidence: 99%

“…The soil water retention curve (WRC), describing the relationship between the soil water content and its corresponding suction head (or matric potential), and the relative hydraulic conductivity (RHC) function, linking the RHC to the soil water content or suction head, are essential properties for setting up models that simulate soil hydrological processes such as groundwater movement, surface runoff, evaporation and solute transport (e.g., Kong et al, 2015; Li et al, 1997; Luo et al, 2018; Nielsen et al, 1986). During the past decades, a number of expressions have been proposed to describe the WRC (e.g., Brooks & Corey, 1964; van Genuchten, 1980; Kosugi, 1996; Assouline, 2001; Assouline & Selker, 2017; Luo et al, 2019; Weber et al, 2019). These WRC expressions assume a constant water content (the residual water content) at high suction head where water movement is neglected.…”

Section: Introductionmentioning

confidence: 99%

Assessment and application of an alternative formula to describe the hydraulic conductivity over the full moisture range

Luo

Kong

Yao

et al. 2022

Hydrological Processes

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Motivated by a versatile three‐parameter water retention curve (WRC) formula of Fredlund and Xing, we proposed an alternative expression to describe the relative hydraulic conductivity (RHC) for soils that can capture oven‐dry to water‐saturated conditions (full moisture range) with a single, closed‐form equation (without having to explicitly partitioning the capillary and film flow components). This RHC expression was tested using an existing data set that includes a wide range of soil textures, and shown to be more accurate than the other two RHC expressions. Subsequently, the new RHC expression was combined with the WRC formula of Fredlund and Xing, generating an alternative model (hereafter called the FL model) applicable to describe soil hydraulic properties over the full moisture range. The FL model requires both the known WRC and RHC data since three additional fitting parameters are involved in the present RHC expression. Furthermore, the FL model was employed in a HYDRUS‐1D numerical model for simulating the soil moisture redistribution within a lysimeter. The numerical simulation with using the FL model can accurately predict the moisture redistribution, in turn confirming the validity of the FL model despite without partitioning the capillary and film flow components.

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“…To solve equation (7c), the relation between  and  is described by a modified van Genuchten model (Troch, 1993;Kong et al, 2016;Luo et al, 2019), where s  [-] is the saturated soil water content, Se is the effective saturation, and 1…”

Section: Relation Between the Effective Porosity And Fluctuation Freq...mentioning

confidence: 99%

Effects of the dynamic effective porosity on watertable fluctuations and seawater intrusion in coastal unconfined aquifers

Luo

Kong

Yao

et al. 2022

Preprint

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Abstract. Watertable fluctuations and seawater intrusion are characteristic features of coastal unconfined aquifers. The dynamic effective porosity due to watertable fluctuations is analyzed and then a modified (empirical) expression is proposed for the dynamic effective porosity based on a dimensionless parameter related to the watertable fluctuation frequency. After validation with both experimental data and numerical simulations, the new expression is implemented in existing Boussinesq equations and a numerical model, allowing for examination of the effects of the dynamic effective porosity on watertable fluctuations and seawater intrusion in coastal unconfined aquifers, respectively. Results show that the Boussinesq equation accounting for the vertical flow in the saturated zone and dynamic effective porosity can accurately predict experimental dispersion relations (that all existing theories fail to predict), highlighting the importance of the dynamic effective porosity in modeling watertable fluctuations in coastal unconfined aquifers. This in turn confirms the utility of the real-valued expression of the dynamic effective porosity. An outcome is that the phase lag between the total moisture (above the watertable) and watertable height measured in laboratory experiments using vertical soil columns (1D systems) can be ignored when predicting watertable fluctuations in coastal unconfined aquifers (2D systems). A dynamic effective porosity that is, by comparison, smaller than the soil porosity leads to a reduction in vertical water exchange between the saturated and vadose zones and hence watertable waves can propagate further landward. The dynamic effective porosity further plays a critical role in simulations of seawater intrusion, since it predicts a more landward seawater-freshwater interface and a higher position of the upper saline plume.

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Evaluation and application of the modified van Genuchten function for unsaturated porous media

Cited by 19 publications

References 41 publications

Soil hydrothermal modeling in a dry alpine agricultural zone: The effect of soil airflow

Soil hydrothermal modeling in a dry alpine agricultural zone: The effect of soil airflow

Assessment and application of an alternative formula to describe the hydraulic conductivity over the full moisture range

Effects of the dynamic effective porosity on watertable fluctuations and seawater intrusion in coastal unconfined aquifers

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