A new model for predicting the hydraulic conductivity of unsaturated porous media

Mualem, Y.

doi:10.1029/wr012i003p00513

Cited by 6,659 publications

(4,789 citation statements)

References 25 publications

Supporting

Mentioning

4,490

Contrasting

Unclassified

267

Order By: Relevance

“…Most of these PTFs were compiled by Schaap et al (2001) and integrated into the Rosetta software package, which estimates the parameters of water retention and the hydraulic conductivity according to models proposed by van Genuchten (1980) and Mualem (1976). Rosetta offers five PTFs that predict hydraulic properties of the soil from limited sets of input data.…”

Section: Pedotransfer Functions (Rosetta Software)mentioning

confidence: 99%

“…Other four models are based on analyses of neural network and usually provide more accurate forecasts, depending on the quality of the input data. Besides the hierarchical approach, the model provides prediction of hydraulic conductivity based on van Genuchten (1980) and Mualem (1976). In this study, 25 soil profiles from the Brazilian Soil Survey (Soil Map of the Federal District -Embrapa 1978) were used to estimate unsaturated K-values by applying PTFs available in the Rosetta software.…”

Section: Pedotransfer Functions (Rosetta Software)mentioning

confidence: 99%

See 1 more Smart Citation

Hydraulic characterization from porous aquifers of the Brazilian Federal District

2015

View full text Add to dashboard Cite

Hydraulic conductivity (K) in unsaturated soil is a key input parameter for modeling subsurface water and solute movements. K-values are also important to better define the potential of aquifers and to optimize water resources management activities. Since K-values are usually not readily available, different techniques are applied to estimate them. This study aimed to estimate unsaturated K-values from porous aquifers found in the Federal District of Brazil. Infiltration tests were conducted in different soil types using the open-end-hole approach and the permeability test using shallow boreholes with specific depths, as reported by Heitfeld in 1979. Soil structure was taken into consideration in such estimations. In order to consider important soil properties such as soil texture and bulk density, K-values were also estimated by means of pedotransfer functions (PTFs). Soil texture was determined in the laboratory and used as input parameter for PTFs. Results from open-end-hole method and permeability test compared to those obtained from pedotransfer functions. K-values from four different shallow porous aquifers systems encountered in the Federal District varied from 10 -8 ms -1 to 10 -6 ms -1 . Highest K-values were found in Oxisols while the lowest rates were found in Inceptisols. Decreasing conductivity trend was found with increasing depth due to the increase of loamy soils. Variations in the rate of hydraulic conductivity indicated heterogeneity of porous aquifers due to differences in textural and structural characteristics of the soils.KEYWORDS: unsaturated hydraulic conductivity; open-end-hole; pedotransfer functions. RESUMO: A condutividade hidráulica (K) em meios não saturados é um parâmetro essencial para modelar fluxos de água e solutos no subsolo. Os valores de K são também importantes para estimar o potencial dos aquíferos e otimizar a gestão de recursos hídricos. Tais valores geralmente não estão disponíveis e diferentes técnicas são aplicadas para obtê-los. O objetivo deste estudo foi estimar valores de K em meios porosos não saturados na região do Distrito Federal (DF). Foram realizados testes de infiltração em diferentes tipos de solo, utilizando o método open-end-hole, e ensaios de permeabilidade, em poços rasos com profundidades específicas, como descritos por Heitfeld (1979). Em tais estimativas a estrutura dos solos foi considerada. Valores de K também foram estimados por meio de funções de pedotransferência (PTFs

show abstract

Section: Pedotransfer Functions (Rosetta Software)mentioning

confidence: 99%

Section: Pedotransfer Functions (Rosetta Software)mentioning

confidence: 99%

Hydraulic characterization from porous aquifers of the Brazilian Federal District

2015

View full text Add to dashboard Cite

show abstract

“…Com base na teoria desenvolvida por Mualem (1976), nas equações combinadas de Van Genuchten (1980) para as funções θ(p/ρg), K(p/ρg) (sendo K a condutividade hidráulica, θ a umidade, e p/ρg a pressão da água no solo), e no argumento de que a forma integrada da lei de Buckingham-Darcy pode produzir uma expressão analítica para a densidade de fluxo mátrico em regime de fluxo não-transiente, então é possível linearizar a equação de Richards no espaço. Com isso, o que restará será uma equação não-linear no tempo, cuja solução poderá ser obtida mediante uma técnica iterativa, como a de NewtonRaphson, por exemplo.…”

Section: Considerações Teóricasunclassified

“…Desde que muitas das propriedades hidráulicas do solo são difíceis de ser obtidas em condições de campo, seja pela variabilidade a que estão sujeitas, seja pelo custo e, ou, demanda de tempo dessas medidas, muitos autores têm procurado estabelecer, modificar ou substabelecer modelos para predizer a condutividade hidráulica como uma função da umidade a partir de outras propriedades hidráulicas mais facilmente mensuráveis, como, por exemplo, da curva de retenção de água do solo e da condutividade hidráulica na saturação (Mualem, 1976;Van Genuchten, 1980 …”

Section: Propriedades Hidráulicas Do Solo E Suas Funções Combinadasunclassified

See 1 more Smart Citation

Modelagem numérica para o processo da evaporação da água do solo

Prevedello¹,

Loyola²

2005

Rev. Bras. Ciênc. Solo

View full text Add to dashboard Cite

RESUMOForam realizados vários ensaios laboratoriais para avaliar o desempenho de um modelo numérico em simular o processo unidimensional da evaporação da água do solo. Este modelo foi desenvolvido a partir da linearização da equação de Richards no espaço e do uso da técnica iterativa de Newton-Raphson, para resolver essa equação não-linear no tempo, e leva em conta o fluxo de vapor dentro do perfil de solo e a taxa de evaporação na sua superfície. Os resultados mostraram que o modelo foi capaz de simular satisfatoriamente o processo, tanto em meios porosos homogêneos quanto estratificados.

show abstract

Model Predictions and Field Measurements of Chlorsulfuron Leaching under Non-steady-state Flow Conditions

Bergström

1996

Pestic. Sci.

View full text Add to dashboard Cite

Model simulations of chlorsulfuron (l-(2-chlorophenylsulfonyl)-3-(4-methoxy-6-methyl-1,3,5-triazin-2-yl)urea) leaching in a loamy soil were made with the mechanistic dual-porosity model MACRO. Comparisons were made with a data set obtained in a lysimeter experiment in which leaching was measured during an l l-month period after applying chlorsulfuron at two rates (4 and 8 g ha-'). In this experiment, peak concentrations appeared c.6 months after pesticide application, reaching levels of 14 and 21 ng litre-' in the low-and high-dose treatments, respectively. These peak concentrations appeared after c.70 mm of accumulated leachate, implying that some of the herbicide was displaced through the soil columns by non-equilibrium flow processes. Model Calibration was limited to parameters related to evapotranspiration, water uptake by iroots and degradation rates in the subsoil. With this minimum amount of Calibration, the model successfully described the leaching pattern of chlorsulfuron, provided that the two-flow domain option in the model was used. Running the model in one-flow domain resulted in considerable underestimates of leaching of chlorsulfuron over the short-term (< 1 year). The degradation rate in the subsoil was also found to be critical. It had to be increased about fivefold to match measured chlorsulfuron concentrations in leachate. At such concentrations, 0.012 g ha-' of chlorsulfuron (0.3% of that applied) was predicted to leach lhrough the soil profile during the 11-month simulation period when the lower dose of the compound was applied.

show abstract

A new model for predicting the hydraulic conductivity of unsaturated porous media

Cited by 6,659 publications

References 25 publications

Hydraulic characterization from porous aquifers of the Brazilian Federal District

Hydraulic characterization from porous aquifers of the Brazilian Federal District

Modelagem numérica para o processo da evaporação da água do solo

Model Predictions and Field Measurements of Chlorsulfuron Leaching under Non-steady-state Flow Conditions

Contact Info

Product

Resources

About