Two‐Dimensional Coupled Hydromechanical Modeling of Water Infiltration into a Transversely Isotropic Unsaturated Soil Region

Wu, Lizhou; Selvadurai, A. P. S.; Huang, Runqiu

doi:10.2136/vzj2013.04.0072

Cited by 19 publications

(7 citation statements)

References 44 publications

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“…It is shown that the pore water pressure dissipation caused by the effect of boundary runoff on the boundary and the transpiration of roots can increase the FOS. Unlike one-dimensional simulation results provided by Wu et al [40], VS always slips when the duration is greater than the lower bound.…”

Section: Effect Of Vegetation Rootcontrasting

confidence: 71%

Effect of Vegetation Roots on the Threshold of Slope Instability Induced by Rainfall and Runoff

2021

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Although vegetation is increasingly used to mitigate landslide risks, how vegetation roots affect the landslide threshold of slope has rarely been explored, particularly in the case of lateral runoff. In this study, we established a two-dimensional saturated-unsaturated infiltration equation considering the hydraulic effects of vegetation roots. The analytical solution for the shallow unsaturated two-dimensional coupled infiltration of vegetated slope (VS) was obtained by a Fourier transform technique. The numerical method was used to evaluate the stability of VS caused by four root architectures, the rainfall amount, and the rainfall duration. Subsequently, the transformation law in runoff, vegetation evaporation, and landslide threshold was analyzed. The results indicate that the factor of safety (FOS) increases with increasing drying time and decreases with increasing depth; the minimum FOS is at the junction of the root-rootless zone. Runoff and vegetation evaporation are favorable for the shallow stability of VS. The time of the safe area is 35 h for rainfall amount 500 m in the uniformly root clay slope. Moreover, four landslide threshold curves that reflected the root architecture, rainfall amount, and rainfall duration are developed, which are more realistic than those created using one-dimensional instability modeling.

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Section: Effect Of Vegetation Rootcontrasting

confidence: 71%

Effect of Vegetation Roots on the Threshold of Slope Instability Induced by Rainfall and Runoff

2021

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“…The RE describes multidimensional unsaturated flow (Wu et al, 2013;Duc et al, 2020). The 2D RE is written as:…”

Section: Numerical Proceduresmentioning

confidence: 99%

Modelling Unsaturated Flow in Porous Media Using an Improved Picard Iteration Scheme

Zhu

2021

Preprint

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The numerical solution of various systems of linear equations describing fluid infiltration uses the Picard iteration (PI). However, because many such systems are ill-conditioned, the solution process often has a poor convergence rate, making it very time-consuming. In this study, a control volume method based on non-uniform nodes is used to discretize the Richards equation, and adaptive relaxation is combined with a multistep preconditioner to improve the convergence rate of PI. The resulting adaptive relaxed PI with multistep preconditioner (MP(m)-ARPI) is used to simulate unsaturated flow in porous media. Three examples are used to verify the proposed schemes. The results show that MP(m)-ARPI can effectively reduce the condition number of the coefficient matrix for the system of linear equations. Compared with conventional PI, MP(m)-ARPI achieves faster convergence, higher computational efficiency, and enhanced robustness. These results demonstrate that improved scheme is an excellent prospect for simulating unsaturated flow in porous media.

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“…Analytical methods for developing the solution to Richards' equation mostly rely on the use of linearization based on Gardner's model. Many articles used such an approach to study flow in an unsaturated zone with infiltration from a variety of surface water bodies (see, e.g., Huang and Wu, 2012;Wu et al, 2013;Wang and Li, 2015). Those articles neglected the presence of an underlying aquifer and treated its water table as the lower boundary with a condition of constant pressure head (e.g., Huang and Wu, 2012) or water content (e.g., Chen et al, 2001b).…”

Section: Introductionmentioning

confidence: 99%

Analysis of three-dimensional unsaturated–saturated flow induced by localized recharge in unconfined aquifers

Chang

Huang

Hund-Der

2018

Hydrol. Earth Syst. Sci.

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In the process of groundwater recharge, surface water usually enters an aquifer by passing an overlying unsaturated zone. Little attention has been given to the development of analytical solutions to a coupled unsaturatedsaturated flow model due to localized recharge up to now. This paper develops a mathematical model to depict threedimensional transient unsaturated-saturated flow in an unconfined aquifer with localized recharge on the ground surface. The model contains Richards' equation for unsaturated flow, a flow equation for saturated formation, and the Gardner constitutive model describing the behavior of unsaturated soil properties. Both flow equations are coupled through the continuity conditions of the head and flux at the water table. The semi-analytical solution to the coupled flow model is derived by the methods of Laplace transform and Fourier cosine transform. A sensitivity analysis is performed to explore the head response to the change in each of the aquifer parameters. A quantitative tool is presented to assess the recharge efficiency signifying the percentage of the water from the recharge to the aquifer. We found that the effect of unsaturated flow on the saturated hydraulic head is negligible if two criteria associated with the unsaturated soil properties and initial aquifer thickness are satisfied. The head distributions predicted from the present solution match well with those from finite-difference simulations. The predictions of the present solution also agree well with the observed data from a field experiment at an artificial recharge pond in Fresno County, California.

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Two‐Dimensional Coupled Hydromechanical Modeling of Water Infiltration into a Transversely Isotropic Unsaturated Soil Region

Cited by 19 publications

References 44 publications

Effect of Vegetation Roots on the Threshold of Slope Instability Induced by Rainfall and Runoff

Effect of Vegetation Roots on the Threshold of Slope Instability Induced by Rainfall and Runoff

Modelling Unsaturated Flow in Porous Media Using an Improved Picard Iteration Scheme

Analysis of three-dimensional unsaturated–saturated flow induced by localized recharge in unconfined aquifers

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