scholarly journals A Nonlinear Solute Transport Model and Data Reconstruction with Parameter Determination in an Undisturbed Soil-Column Experiment

2011 ◽  
Vol 2011 ◽  
pp. 1-14 ◽  
Author(s):  
Gongsheng Li ◽  
De Yao ◽  
Yongzai Wang ◽  
Xianzheng Jia
Keyword(s):  
Inverse Problem ◽  
Solute Transport ◽  
Transport Model ◽  
Soil Column ◽  
Parameter Determination ◽  
Nonlinear Transport ◽  
Inversion Algorithm ◽  
Unknown Parameters ◽  
Undisturbed Soil ◽  
Optimal Perturbation

A real undisturbed soil-column infiltrating experiment in Zibo, Shandong, China, is investigated, and a nonlinear transport model for a solute ion penetrating through the column is put forward by using nonlinear Freundlich's adsorption isotherm. Since Freundlich's exponent and adsorption coefficient and source/sink terms in the model cannot be measured directly, an inverse problem of determining these parameters is encountered based on additional breakthrough data. Furthermore, an optimal perturbation regularization algorithm is introduced to determine the unknown parameters simultaneously. Numerical simulations are carried out and then the inversion algorithm is applied to solve the real inverse problem and reconstruct the measured data successfully. The computational results show that the nonlinear advection-dispersion equation discussed in this paper can be utilized by hydrogeologists to research solute transport behaviors with nonlinear adsorption in porous medium.

A Two-Domain Approach to Model Solute Transport in an Undisturbed Soil Column using X-Ray CAT Scanning

2013 ◽  
Author(s):  
J. Perret ◽  
S.O. Prasher ◽  
A. Kanztas ◽  
and C. Langford
Keyword(s):  
Solute Transport ◽  
Soil Column ◽  
Undisturbed Soil ◽  
X Ray

scholarly journals Evaluation of Solute Transport in Undisturbed Soil Column under Steady Unsaturated Flow Conditions.

1997 ◽  
pp. 61-70
Author(s):  
Masato Horiuchi ◽  
Yoriteru Inoue ◽  
Shinsuke Morisawa ◽  
Barokah Aliyanta
Keyword(s):  
Solute Transport ◽  
Unsaturated Flow ◽  
Soil Column ◽  
Flow Conditions ◽  
Undisturbed Soil

scholarly journals Bayesian estimation of the hydraulic and solute transport properties of a small-scale unsaturated soil column

2016 ◽  
Vol 64 (1) ◽  
pp. 30-44 ◽  
Author(s):  
Paulo H. S. Moreira ◽  
Martinus Th. van Genuchten ◽  
Helcio R. B. Orlande ◽  
Renato M. Cotta
Keyword(s):  
Solute Transport ◽  
Transport Properties ◽  
Unsaturated Soil ◽  
Soil Column ◽  
Column Experiment ◽  
Richards Equation ◽  
Small Scale ◽  
Transport Parameters ◽  
Unknown Parameters ◽  
Concentration Data

Abstract In this study the hydraulic and solute transport properties of an unsaturated soil were estimated simultaneously from a relatively simple small-scale laboratory column infiltration/outflow experiment. As governing equations we used the Richards equation for variably saturated flow and a physical non-equilibrium dual-porosity type formulation for solute transport. A Bayesian parameter estimation approach was used in which the unknown parameters were estimated with the Markov Chain Monte Carlo (MCMC) method through implementation of the Metropolis-Hastings algorithm. Sensitivity coefficients were examined in order to determine the most meaningful measurements for identifying the unknown hydraulic and transport parameters. Results obtained using the measured pressure head and solute concentration data collected during the unsaturated soil column experiment revealed the robustness of the proposed approach.

scholarly journals Field-scale solute transport parameters derived from tracer tests in large undisturbed soil columns

Soil Research ◽  
2014 ◽  
Vol 52 (1) ◽  
pp. 13 ◽  
Author(s):  
Dirk Mallants
Keyword(s):  
Solute Transport ◽  
Transport Model ◽  
Linear Regression Analysis ◽  
Local Scale ◽  
Time Domain Reflectometry ◽  
Hydrodynamic Dispersion ◽  
Transport Parameters ◽  
Field Scale ◽  
Soil Columns ◽  
Undisturbed Soil

Transport parameters obtained from laboratory tracer experiments were used to evaluate the stochastic form of the equilibrium convection–dispersion equation (CDE) in describing the transition of scale, i.e. from the column or local scale to a larger field scale. Local-scale solute breakthrough curves (BTCs) were measured in 1-m-long and 0.3-m-diameter undisturbed soil columns by means of time-domain reflectometry at six depths for a 79-h input pulse of chloride. The local-scale data were analysed in terms of the equilibrium CDE and the mobile–immobile non-equilibrium transport model (MIM). At the local scale, the MIM transport model better described the observed early breakthrough and the tailing of the BTC than did the CDE. A linear regression analysis indicated that the relationship between the hydrodynamic dispersion D and pore-water velocity v was of the form D = 31vl.92 (correlation ρv,D = 0.74). Averaging of the local-scale BTCs across the field produced a large-scale or field-scale mean BTC; at the greatest observation depth (0.8 m) the field-scale dispersivity <D>/<v> = λ equals 0.656 m. The results further showed that for large values of the mean dispersion coefficient, <D>, local-scale dispersion is an important mechanism for field-scale solute spreading, whereas the standard deviation, σD, and the correlation between v and D, ρvD, have negligible effects on field-scale transport. Stochastic stream tube models supplemented with statistical properties of local-scale transport parameters provide a practical and computationally efficient tool to describe heterogeneous solute transport at large spatial scales.

scholarly journals Bayesian Simultaneous Estimation of Unsaturated Flow and Solute Transport Parameters from a Laboratory Infiltration Experiment

Water ◽  
2019 ◽  
Vol 11 (8) ◽  
pp. 1660 ◽  
Author(s):  
Anis Younes ◽  
Jabran Zaouali ◽  
Sabri Kanzari ◽  
Francois Lehmann ◽  
Marwan Fahs
Keyword(s):  
Mass Transport ◽  
Solute Transport ◽  
Unsaturated Flow ◽  
Soil Column ◽  
Accurate Estimation ◽  
Soil Parameters ◽  
Simultaneous Estimation ◽  
Transport Parameters ◽  
Undisturbed Soil ◽  
Infiltration Experiment

Numerical modeling has become an irreplaceable tool for the investigation of water flow and solute transport in the unsaturated zone. The use of this tool for real situations is often faced with lack of knowledge of hydraulic and soil transport parameters. In this study, advanced experimental and numerical techniques are developed for an accurate estimation of the soil parameters. A laboratory unsaturated flow and solute transport experiment is conducted on a large undisturbed soil column of around 40 cm length. Bromide, used as a nonreactive contaminant, is injected at the surface of the undisturbed soil, followed by a leaching phase. The pressure measurements at different locations along the soil column as well as the outflow bromide concentration are collected during the experiment and used for the statistical calibration of flow and solute transport. The Richards equation, combined with constitutive relations for water content and permeability, is used to describe unsaturated flow. Both linear and non-equilibrium mobile–immobile transport models are investigated for the solute transport. All hydraulic and mass transport parameters are inferred using a one-step Bayesian estimation with the Markov chain Monte Carlo sampler. The results prove that the pressure and concentration measurements are able to identify almost all hydraulic and mass transport parameters. The mobile–immobile transport model better reproduces the infiltration experiment. It produces narrower uncertainty intervals for soil parameters and predictive output concentrations.

scholarly journals Simulation and Prediction of Ion Transport in the Reclamation of Sodic Soils with Gypsum Based on the Support Vector Machine

2014 ◽  
Vol 2014 ◽  
pp. 1-9
Author(s):  
Jinman Wang ◽  
Zhongke Bai ◽  
Peiling Yang
Keyword(s):  
Support Vector Machine ◽  
Solute Transport ◽  
Transport Model ◽  
Soil Column ◽  
Support Vector ◽  
Hydrodynamic Dispersion ◽  
Sodic Soils ◽  
Solute Content ◽  
Svm Model ◽  
Retardation Coefficient

The effect of gypsum on the physical and chemical characteristics of sodic soils is nonlinear and controlled by multiple factors. The support vector machine (SVM) is able to solve practical problems such as small samples, nonlinearity, high dimensions, and local minima points. This paper reports the use of the SVM regression method to predict changes in the chemical properties of sodic soils under different gypsum application rates in a soil column experiment and to evaluate the effect of gypsum reclamation on sodic soils. The research results show that (1) the SVM soil solute transport model using the Matlab toolbox represents the change in Ca2+and Na+in the soil solution and leachate well, with a high prediction accuracy. (2) Using the SVM model to predict the spatial and temporal variations in the soil solute content is feasible and does not require a specific mathematical model. The SVM model can take full advantage of the distribution characteristics of the training sample. (3) The workload of the soil solute transport prediction model based on the SVM is greatly reduced by not having to determine the hydrodynamic dispersion coefficient and retardation coefficient, and the model is thus highly practical.

Parameter Determination for Chloride and Tritium Transport in Undisturbed Lysimeters during Steady Flow

1992 ◽  
Vol 23 (2) ◽  
pp. 89-104 ◽  
Author(s):  
Ole H. Jacobsen ◽  
Feike J. Leij ◽  
Martinus Th. van Genuchten
Keyword(s):  
Experimental Data ◽  
Unsaturated Flow ◽  
Transport Model ◽  
Time Moment ◽  
Breakthrough Curves ◽  
Coarse Sand ◽  
Retardation Factor ◽  
Parameter Determination ◽  
Model Parameters ◽  
Water Fraction

Breakthrough curves of Cl and 3H2O were obtained during steady unsaturated flow in five lysimeters containing an undisturbed coarse sand (Orthic Haplohumod). The experimental data were analyzed in terms of the classical two-parameter convection-dispersion equation and a four-parameter two-region type physical nonequilibrium solute transport model. Model parameters were obtained by both curve fitting and time moment analysis. The four-parameter model provided a much better fit to the data for three soil columns, but performed only slightly better for the two remaining columns. The retardation factor for Cl was about 10 % less than for 3H2O, indicating some anion exclusion. For the four-parameter model the average immobile water fraction was 0.14 and the Peclet numbers of the mobile region varied between 50 and 200. Time moments analysis proved to be a useful tool for quantifying the break through curve (BTC) although the moments were found to be sensitive to experimental scattering in the measured data at larger times. Also, fitted parameters described the experimental data better than moment generated parameter values.

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