Estimation of van Genuchten Equation Parameters in Laboratory and through Inverse Modeling with Hydrus-1D

Soil water retention curve (SWRC) becomes important because it guides when and how much to irrigate, optimizing the use of water; can be obtained in the field or laboratory, being commonly determined in the laboratory with porous plate apparatus, and the determination is compromised by issues such as time and labor. In this context, inverse modeling emerges, which allows to obtain a variable going from the effect to the cause, using Hydrus-1D. Hence, this study aims to obtain van Genuchten equation parameters through inverse modeling with Hydrus-1D and make the respective comparisons and inferences. Matric potential data were obtained over time in an instantaneous profile-type experiment. Six sets of three tensiometers each were installed surrounding the center of the experimental plot, at depths of 0.20, 0.35 and 0.50 m. Target depth was 0.35 m, where the roots of most crops are concentrated, and the other tensiometers were used to obtain the potential gradient. Matric potential data were used to feed Hydrus-1D and obtain the van Genuchten equation parameters. Laboratory curves were obtained using porous plate apparatus, with four replicates. It was concluded that, in general, the Hydrus-1D model estimates van Genuchten equation parameters and, consequently, the SWCC of an Argissolo more consistently with field conditions than those obtained in the laboratory; and, provided it is fed with field data, the Hydrus-1D simulates well the behavior of matric potential and moisture over time, reducing the time and labor in the procedures to obtain van Genuchten equation parameters in the laboratory.

Download Full-text

Filter Paper Method for the Determination of the Soil Water Retention Curve

Revista Brasileira de Ciência do Solo ◽

10.1590/01000683rbcs20140546 ◽

2015 ◽

Vol 39 (5) ◽

pp. 1344-1352 ◽

Cited By ~ 3

Author(s):

Eurileny Lucas de Almeida ◽

Adunias dos Santos Teixeira ◽

Francisco Chagas da Silva Filho ◽

Raimundo Nonato de Assis Júnior ◽

Raimundo Alípio de Oliveira Leão

Keyword(s):

Filter Paper ◽

Water Retention ◽

Water Retention Curve ◽

Soil Water Retention Curve ◽

Soil Water Retention ◽

Matric Potential ◽

Retention Curve ◽

Filter Paper Method ◽

Van Genuchten Model ◽

Paper Method

ABSTRACT High cost and long time required to determine a retention curve by the conventional methods of the Richards Chamber and Haines Funnel limit its use; therefore, alternative methods to facilitate this routine are needed. The filter paper method to determine the soil water retention curve was evaluated and compared to the conventional method. Undisturbed samples were collected from five different soils. Using a Haines Funnel and Richards Chamber, moisture content was obtained for tensions of 2; 4; 6; 8; 10; 33; 100; 300; 700; and 1,500 kPa. In the filter paper test, the soil matric potential was obtained from the filter-paper calibration equation, and the moisture subsequently determined based on the gravimetric difference. The van Genuchten model was fitted to the observed data of soil matric potential versus moisture. Moisture values of the conventional and the filter paper methods, estimated by the van Genuchten model, were compared. The filter paper method, with R2 of 0.99, can be used to determine water retention curves of agricultural soils as an alternative to the conventional method.

Download Full-text

Measurement systems of soil water matric potential and evaluation of soil moisture under different irrigation depths

Engenharia Agrícola ◽

10.1590/s0100-69162012000300006 ◽

2012 ◽

Vol 32 (3) ◽

pp. 467-478 ◽

Cited By ~ 3

Author(s):

José M. G. Beraldo ◽

José E. Cora ◽

Edemo J. Fernandes

Keyword(s):

Soil Moisture ◽

Soil Water ◽

Water Retention Curve ◽

Soil Matric Potential ◽

Soil Water Retention Curve ◽

Soil Water Retention ◽

Matric Potential ◽

Measurement Systems ◽

Neutron Attenuation ◽

New Methodologies

The development of new methodologies and tools that enable to determine the water content in soil is of fundamental importance to the practice of irrigation. The objective of this study was to evaluate soil matric potential using mercury tensiometer and puncture digital tensiometer, and to compare the gravimetric soil moisture values obtained by tensiometric system with gravimetric soil moisture obtained by neutron attenuation technique. Four experimental plots were maintained with different soil moisture by irrigation. Three repetitions of each type of tensiometer were installed at 0.20 m depth. Based on the soil matric potential and the soil water retention curve, the corresponding gravimetric soil moisture was determined. The data was then compared to those obtained by neutron attenuation technique. The results showed that both tensiometric methods showed no difference under soil matric potential higher than -40 kPa. However, under drier soil, when the water was replaced by irrigation, the soil matric potential of the puncture digital tensiometer was less than those of the mercury tensiometer.

Download Full-text

Evaluation of installation procedures of volumetric water content and matric potential probes: fundamentals for obtaining field and laboratory accordance

MATEC Web of Conferences ◽

10.1051/matecconf/202133701009 ◽

2021 ◽

Vol 337 ◽

pp. 01009

Author(s):

Carnavale Thiago de Souza ◽

Campos Tácio Mauro Pereira de ◽

Lopes Haimon Diniz Alves

Keyword(s):

Water Content ◽

Bulk Density ◽

Volumetric Water Content ◽

Water Retention Curve ◽

Soil Water Retention Curve ◽

Soil Water Retention ◽

Matric Potential ◽

Retention Curve ◽

Double Ring ◽

Hydraulic Equipment

The current paper aims to analyze the influence of installation procedures when it comes to the accordance of the Soil Water Retention Curve and field monitoring data. The method comprises testing three different installation procedures: with driving the rod into the soil; with the application of mud inside the auger hole; and with a hardened steel gauge. Further, is evaluated the influence of the variation of Bulk density on volumetric water content values by using the Proctor and a double ring hydraulic equipment. To analyze the soil-rod coupling, a microtomography imaging routine was performed. The results point out that the probe’s data are connected to the Bulk density of the material, producing higher volumetric water content values with the increase of Bulk density. Comparing results of different installation methods with laboratory results, it is possible to conclude that driving the rod directly into the soil is the best way to install the equipment since the probe underestimates the volumetric water content data by 2,5%, while the mud application by 4%, and the gauge method by 5%.

Download Full-text

ANÁLISE COMPARATIVA DE MÉTODOS PARA DETERMINAÇÃO DA CURVA DE RETENÇÃO DE ÁGUA EM SOLOS

Irriga ◽

10.15809/irriga.2008v13n4p517-524 ◽

2008 ◽

Vol 13 (4) ◽

pp. 517-524 ◽

Cited By ~ 2

Author(s):

Maria Hermínia Ferreira Tavares ◽

José Jeremias da Silva Feliciano ◽

Carlos Manoel Pedro Vaz

Keyword(s):

Soil Water ◽

Water Retention ◽

Water Retention Curve ◽

Soil Water Retention Curve ◽

Soil Water Retention ◽

Retention Curve ◽

Pressure Plate ◽

Van Genuchten Model ◽

Mesh Sieve ◽

Plate Apparatus

ANÁLISE COMPARATIVA DE MÉTODOS PARA DETERMINAÇÃO DA CURVA DE RETENÇÃO DE ÁGUA EM SOLOS Maria Hermínia Ferreira Tavares1; José Jeremias da Silva Feliciano1; Carlos Manoel Pedro Vaz21Centro de Ciências Exatas e Tecnológicas, Universidade Estadual do Oeste do Paraná, Cascavel, PR, [email protected] 2Empresa Brasileira de Pesquisa Agropecuária, Embrapa Instrumentação Agropecuária, São Carlos, SP. 1 RESUMO O tradicional método de obtenção da curva de retenção de água no solo através da Câmara de Pressão de Richards é trabalhoso e demorado. Assim, este trabalho teve como objetivo avaliar o emprego de dois diferentes equipamentos TDR, conjugados a tensiômetros, para obter os valores de umidade volumétrica e respectivos valores de tensão, comparando-os aos resultados fornecidos pelo método tradicional. Para as medidas através dos equipamentos TDR, o solo, classificado como Latossolo Vermelho distroférrico (LVdf), foi seco ao ar e passado através de uma peneira2 mm. Os dados de curva de retenção foram ajustados utilizando-se o programa Origin 6.0 Professional através do modelo sugerido por Van Genuchten. A análise dos dados obtidos, realizada através do índice de desempenho c, mostrou que os 2 equipamentos TDR apresentaram performances similares. UNITERMOS: Câmara de Richards, técnica TDR, tensiometria. TAVARES, M. H. F.; FELICIANO, J. J. S.; VAZ, C. M. P. COMPARATIVE ANALYSIS OF METHODS TO DETERMINE THE SOIL WATER RETENTION CURVE 2 ABSTRACT The traditional method to obtain the soil water retention curve using Richard’s pressure plate apparatus is laborious and time consuming. Thus, the objective of this work was to evaluate the use of two different TDR equipments, coupled to tensiometers, to obtain soil volumetric water content and respective tension values compared to those from traditional methods. For TDR measurements, a Rhodic Hapludox soil was air-dried and passed through a2 mm mesh sieve. Data of water retention curve were adjusted using the Origin 6.0 Professional software and the Van Genuchten model. The analysis of data based on the performance index revealed that the two TDR equipments had similar performances. KEY WORDS: Richard’s pressure plate apparatus, TDR technique, tensiometry.

Download Full-text