Validity limits for the van Genuchten–Mualem model and implications for parameter estimation and numerical simulation

Ippisch, Olaf; Vogel, Hans‐Jörg; Bastian, Peter

doi:10.1016/j.advwatres.2005.12.011

Cited by 211 publications

(219 citation statements)

References 10 publications

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“…In contrast, Vogel et al (2000) reported the parameter to be quite sensitive. Ippisch et al (2006) demonstrated that the van Genuchten-Mualem model caused convergence problems with n close to 1.0 for the numerical solver, which we can confirm.…”

Section: Parameter Uncertaintysupporting

confidence: 70%

Monte Carlo-based calibration and uncertainty analysis of a coupled plant growth and hydrological model

et al. 2014

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Abstract.Computer simulations are widely used to support decision making and planning in the agriculture sector. On the one hand, many plant growth models use simplified hydrological processes and structures -for example, by the use of a small number of soil layers or by the application of simple water flow approaches. On the other hand, in many hydrological models plant growth processes are poorly represented. Hence, fully coupled models with a high degree of process representation would allow for a more detailed analysis of the dynamic behaviour of the soil-plant interface.We coupled two of such high-process-oriented independent models and calibrated both models simultaneously. The catchment modelling framework (CMF) simulated soil hydrology based on the Richards equation and the van Genuchten-Mualem model of the soil hydraulic properties. CMF was coupled with the plant growth modelling framework (PMF), which predicts plant growth on the basis of radiation use efficiency, degree days, water shortage and dynamic root biomass allocation.The Monte Carlo-based generalized likelihood uncertainty estimation (GLUE) method was applied to parameterize the coupled model and to investigate the related uncertainty of model predictions. Overall, 19 model parameters (4 for CMF and 15 for PMF) were analysed through 2 × 10 6 model runs randomly drawn from a uniform distribution.The model was applied to three sites with different management in Müncheberg (Germany) for the simulation of winter wheat (Triticum aestivum L.) in a cross-validation experiment. Field observations for model evaluation included soil water content and the dry matter of roots, storages, stems and leaves. The shape parameter of the retention curve n was highly constrained, whereas other parameters of the retention curve showed a large equifinality. We attribute this slightly poorer model performance to missing leaf senescence, which is currently not implemented in PMF. The most constrained parameters for the plant growth model were the radiation-use efficiency and the base temperature. Cross validation helped to identify deficits in the model structure, pointing out the need for including agricultural management options in the coupled model.

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Section: Parameter Uncertaintysupporting

confidence: 70%

Monte Carlo-based calibration and uncertainty analysis of a coupled plant growth and hydrological model

et al. 2014

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“…fonction de conductivité hydraulique en milieu non saturé donnée par l'équation modifiée de Mualem-van Genuchten expression (IPPISCH et al, 2006), K K A est un tenseur anisotropique adimensionnel. avec Q adv-DispK,Ej le flux advectif-dispersif à travers la facette E j appartenant à l'élément K et dont la formulation est donnée ci-dessous :…”

Section: Modèle Hydrodynamique Bidimensionnel (2d)unclassified

“…Il consiste en une infiltration dans une colonne de sol (L = 100 cm) non saturé. Les paramètres spécifiques du sol sont donnés au tableau 1, où : θ r et θ s sont respectivement les teneurs en eau résiduelle et à saturation; K s est la conductivité hydraulique à saturation, α est un paramètre de fitting, n et m sont des paramètres liés à la distribution de la taille des pores, h e est la valeur d'entrée d'air (IPPISCH, 2006). …”

Section: Cas Test En Monodimensionnelunclassified

Modélisation du transport de soluté en milieux poreux par la méthode d’éléments finis mixtes hybrides – développement d’un limiteur de flux

Wanko

Tapia-Padilla

Mosé

et al. 2009

rseau

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RésuméUne méthode d’éléments finis mixte hybride est appliquée pour l’approximation de l’écoulement associé au transport en milieu poreux non saturé. Le développement de ce modèle s’effectue dans le cadre du projet européen ARWET, lequel a pour objectif l’étude de nouvelles potentialités de dissipation des pesticides dans les zones humides. La formulation du modèle bidimensionnel est fondée sur les propriétés de l’espace de Raviart-Thomas. L’écueil numérique que posent les problèmes à convection dominante est surmonté par l’introduction d’un limiteur de flux alors qu’un limiteur de pente est généralement utilisé dans la littérature. Le limiteur suggéré est inconditionnellement stable et permet de conserver la précision des résultats à nombre de Peclet élevé.

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“…Other parameter constraints for the van GenuchtenMualem equations were discussed by Fuentes et al (1991) and Ippisch et al (2006).…”

Section: Theorymentioning

confidence: 99%

Revisiting the S-index for soil physical quality and its use in Brazil

Lier

2014

Rev. Bras. Ciênc. Solo

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SUMMARYThe S-index was introduced in 2004 in a publication by A.R. Dexter. S was proposed as an indicator of soil physical quality. A critical value delimiting soils with rich and poor physical quality was proposed. At present, Brazil is world leader in citations of Dexter´s publication. In this publication the S-theory is mathematically revisited and extended. It is shown that S is mathematically correlated to bulk density and total porosity. As an absolute indicator, the value of S alone has proven to be incapable of predicting soil physical quality. The critical value does not always hold under boundary conditions described in the literature. This is to be expected because S is a static parameter, therefore implicitly unable to describe dynamic processes. As a relative indicator of soil physical quality, the S-index has no additional value over bulk density or total porosity. Therefore, in the opinion of the author, the fact that bulk density or total porosity are much more easily determined than the water retention curve for obtaining S disqualifies S as an advantageous indicator of relative soil physical quality. Among the several equations available for the fitting of water retention curves, the Groenevelt-Grant equation is preferable for use with S since one of its parameters and S are linearly correlated. Since efforts in soil physics research have the purpose of describing dynamic processes, it is the author´s opinion that these efforts should shift towards mechanistic soil physics as opposed to the search for empirical correlations like S which, at present, represents far more than its reasonable share of soil physics in Brazil.

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Validity limits for the van Genuchten–Mualem model and implications for parameter estimation and numerical simulation

Cited by 211 publications

References 10 publications

Monte Carlo-based calibration and uncertainty analysis of a coupled plant growth and hydrological model

Monte Carlo-based calibration and uncertainty analysis of a coupled plant growth and hydrological model

Modélisation du transport de soluté en milieux poreux par la méthode d’éléments finis mixtes hybrides – développement d’un limiteur de flux

Revisiting the S-index for soil physical quality and its use in Brazil

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