A Modified van Genuchten-Mualem Model of Hydraulic Conductivity in Korean Residual Soils

Oh, Se Baek; Kim, Yun Ki; Kim, Junwoo

doi:10.3390/w7105487

Cited by 18 publications

(19 citation statements)

References 19 publications

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“…The analysis used databases in which the parameter l in the van Genuchten‐Mualem equation (van Genuchten, ) had a standard value of 1/2. In recent years, a number of experimental works have been published indicating that parameter l may not always be equal to 1/2 (Oh et al, ; T. Wang et al, ) and it can take both positive and negative values.…”

Section: Simulation Resultsmentioning

confidence: 99%

An Approximate Model for Predicting the Specific Yield Under Periodic Water Table Oscillations

Pozdniakov

Wang

Lekhov

2019

Water Resources Research

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Predicting specific yield for a given aquifer remains a great challenge due to its dynamic characteristics, especially under periodic (e.g., seasonal and diurnal) groundwater level fluctuations. In this study, a dimensionless period of groundwater level fluctuations, which depends on the saturated hydraulic conductivity, the length of the groundwater level fluctuation period, and the soil water retention properties, is first introduced. Then, the relationship between the predicted specific yield and the dimensionless period of groundwater level fluctuations is defined based on the theory of variably saturated flow. The proposed approximate formula is tested by series of simulations of variably saturated flow within homogeneous and isotropic porous media with the Hydrus‐1D program. The results of numerical experiments demonstrate an invariant relationship between the predicted specific yield and the dimensionless period for a wide range of changes in the dimensionless period of groundwater level oscillations. Furthermore, the sensitivity analysis of the dependence of the predicted specific yield on the van Genuchten parameters indicates the applicability of estimating the specific yield via van Genuchten parameters, which can be predicted by the soil texture classes for a given length of the oscillation period and a known saturated hydraulic conductivity in the zone of groundwater level fluctuations. The proposed model can be used for predicting the dynamics of the specific yield under seasonal or diurnal groundwater level fluctuations.

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Section: Simulation Resultsmentioning

confidence: 99%

An Approximate Model for Predicting the Specific Yield Under Periodic Water Table Oscillations

Pozdniakov

Wang

Lekhov

2019

Water Resources Research

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Section: Of 21mentioning

confidence: 99%

“…Not only intensity and duration of rainfall but also hydraulic properties of soils near the surface, that is permeability, unsaturated hydraulic conductivity, and soil-water characteristics, have a great effect on the rainfall infiltration [7,8]. In particular, the unsaturated hydraulic conductivity is an important factor in understanding the hydraulic characteristics of unsaturated soils [7]. The unsaturated hydraulic conductivity function has been estimated by a variety of methods through the use of the soil-water retention curve (SWRC) or the simplified model because of the difficulty of experimental measurements [9][10][11][12][13][14].…”

Section: Of 21mentioning

confidence: 99%

Slope Stability Analysis of Unsaturated Soil Slopes Based on the Site-Specific Characteristics: A Case Study of Hwangryeong Mountain, Busan, Korea

2020

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Shallow slope failures occur almost every year during the rainy season. Continuous observation of the meteorological parameters and hydrological characteristics is required to more clearly understand the triggering mechanisms of shallow slope failure. In addition, influential factors, such as type of relative permeability models, air flow, and variation of hydraulic conductivity associated with stress–strain behavior of soil, have significant effects on the actual mechanism of rainfall infiltration. Real-time data including hourly rainfall and pore water pressure in response to rainfall was recorded by devices; then, the change in pore pressure from the devices was compared to the results from the infiltration analysis with applications of three relative permeability models, air flow, and the coupled hydro-mechanical analysis to examine an appropriate site-specific approach to a rainfall infiltration analysis. The infiltration and stability analyses based on the site-specific hydrologic characteristics were utilized to create maps of safety factors that depend on the cumulative rainfall. In regions vulnerable to landslides, rainfall forecast information and safety factor maps built by applying various rainfall scenarios can be useful in preparing countermeasures against disasters during the rainy season.

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“…7 Over recent years, the above-mentioned models have been widely modified or improved by various researchers. [8][9][10][11] Based on the measured soilwater characteristic curve (SWCC), Li et al 12 described the relationship between the unsaturated loess coefficient of permeability and the matrix suction or water content by using CCG model. By combining SWCC models (i.e.…”

Section: Introductionmentioning

confidence: 99%

A Unified Fractal Model for Permeability Coefficient of Unsaturated Soil

Tao

Xiao

et al. 2019

Fractals

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Due to the significant challenges in the measurements, evaluation of permeability coefficient for unsaturated soil is of immense importance for investigating the seepage and hydro-mechanical coupling problems of unsaturated soil. However, the predictions of existing typical models reveal significance divergence for permeability coefficient of unsaturated soils even under identical conditions. In particular, the existing models are greatly restricted in their practical application due to their complexity in the form of integral expressions that require significant computational effort. Here, a simplified unified model is presented to estimate the relative permeability coefficient. First, a fractal-form of soil–water characteristic curve (SWCC) is derived from fractal theory. Then, on the basis of the proposed SWCC models, the classical models (i.e. Childs and Collis-George (CCG) model, Burdine model, Mualem model and Tao and Kong model, respectively) for evaluating the permeability coefficient of unsaturated soil are converted to be presented in fractal forms. It is interestingly found that the fractal forms of these models are enormously similar. Based on these observations, a simplified unified fractal model for the relative permeability coefficient of unsaturated soil is proposed, where only two parameters (i.e. fractal dimension and air-entry value) are included, thereby significantly reducing the computational efforts. The detailed procedure for determining model parameters is elaborated. The accuracy of this model is verified by comparing its predictions with the experimental data for over 12 types of unsaturated soils. The results highlight that, compared with existing models, the proposed model would be much more efficiently used for estimating the relative permeability coefficient of unsaturated soils, thereby facilitating its application for investigating the associated seepage and hydro-mechanical coupling problems in practice.

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A Modified van Genuchten-Mualem Model of Hydraulic Conductivity in Korean Residual Soils

Cited by 18 publications

References 19 publications

An Approximate Model for Predicting the Specific Yield Under Periodic Water Table Oscillations

An Approximate Model for Predicting the Specific Yield Under Periodic Water Table Oscillations

Slope Stability Analysis of Unsaturated Soil Slopes Based on the Site-Specific Characteristics: A Case Study of Hwangryeong Mountain, Busan, Korea

A Unified Fractal Model for Permeability Coefficient of Unsaturated Soil

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