Unsaturated Hydraulic Properties from Upward Flow into Soil Cores

Hudson, David; Wierenga, P. J.; Hills, R. G.

doi:10.2136/sssaj1996.03615995006000020009x

Cited by 46 publications

(32 citation statements)

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“…This method successfully solved the so-called "traveling salesman problem" and the problem of optimally arranging several hundred thousand circuit elements on a tiny silicon substrate [Press et al, 1992] The objective of this paper is to develop an effective and efficient inverse parameter estimator that can be used to find unique and stable parameter estimation given that the experiment is well designed to ensure identifiability. We will apply the estimation to the upward infiltration experiment described by Hudson et al [1996]. A key step in our work is the development of a new technique of combining the classical downhill simplex method with the simulated annealing method in order to find the global minimum of the objective function in an efficient and effective manner.…”

Section: Introductionmentioning

confidence: 99%

A hybrid global optimization method for inverse estimation of hydraulic parameters: Annealing‐Simplex Method

Pan¹,

Wu²

1998

Water Resources Research

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Abstract. Inverse estimation of unsaturated hydraulic parameters is often a highly nonlinear optimization problem with multiple parameters. The objective functions involved are often topographically complex and may contain many local minima. Because of these reasons, the inverse solutions are commonly very sensitive to the initial guess of the parameters when conventional optimizers are used. This paper presents an annealingsimplex method that incorporates simulated annealing strategies into a classical downhill simplex method. An upward infiltration experiment was used as an example of inverse estimation to test the method. Numerical experiments of both minimizing an algebraic function and inversion of upward infiltration data showed that the new method successfully converged to the global minimum in all cases, irrespective of the initial hydraulic parameter estimates, while the classical downhill method often converged to unfavorable local minima. The CPU times needed for the annealing-simplex method to estimate 5 and 7 hydraulic parameters simultaneously are about a half hour and 1 hour on a PC, respectively. Additionally, no special requirements are imposed on the objective function, and the method is independent of the details of the simulation submodel. Therefore the proposed method should be applicable to other optimization problems in water resources when it is important to have a robust global search capability. IntroductionKnowledge of unsaturated soil hydraulic properties is essential for prediction of water flow and contaminant transport through the vadose zone. Specifically, the hydraulic properties are the water retention and hydraulic conductivity functions, both of which are highly nonlinear functions of the soil water pressure head. As opposed to more classical direct method, inverse estimation of the hydraulic properties from transient flow experiments has recently become more popular because of its flexibility in considering various data types, availability of more powerful computers, and the presence of increasingly accurate flow simulators [Kool and Parker, 1988 Hence, like many other geophysical inverse problems, the inverse estimation of hydraulic parameters of soils is a strongly nonlinear and multiparameter optimization problem that often involves finding the global minimum in between many local minima. The simulated annealing method, first incorporated into numerical calculations by Metropolis et al. The objective of this paper is to develop an effective and efficient inverse parameter estimator that can be used to find unique and stable parameter estimation given that the experiment is well designed to ensure identifiability. We will apply the estimation to the upward infiltration experiment described by Hudson et al. [1996]. A key step in our work is the development of a new technique of combining the classical downhill simplex method with the simulated annealing method in order to find the global minimum of the objective function in an efficient and effective manner. Being different ...

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Section: Introductionmentioning

confidence: 99%

A hybrid global optimization method for inverse estimation of hydraulic parameters: Annealing‐Simplex Method

Pan¹,

Wu²

1998

Water Resources Research

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“…The advance of the wetting front with time and the amount of water infiltrated are recorded. From these data, Shao and Horton (1998) (Hudson et al, 1996), a constant flux of water is imposed at the bottom of the soil sample, and pressure heads are measured inside the sample using tensiometers. To maximize information for the inverse analysis, Young et al (2002) suggested to initiate infiltration by a certain tension at the bottom of the sample, using a Mariotte system, rather than by imposing a boundary flux.…”

Section: Transient Laboratory Methodsmentioning

confidence: 99%

Determining Soil Hydraulic Properties

Durner

Lipsius

2005

Encyclopedia of Hydrological Sciences

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Hydraulic properties are required for modeling water and solute transport in unsaturated soils. The bottleneck for the successful application of numerical simulation models lays usually in their parameter estimation requirements. Methods to determine hydraulic properties can be classified into indirect and direct approaches. Indirect methods encompass the estimation of hydraulic properties by pedotransfer functions from more easily measured soil properties, and the prediction of the unsaturated hydraulic conductivity function from the water retention curve ( WRC ). In direct methods, observations of flow attributes from laboratory or field experiments are evaluated. This article reviews common methods to estimate the hydraulic conductivity function from the water retention characteristic and various direct measurement techniques in the laboratory and the field. We conclude with an outlook on contemporary developments in measurement techniques, stressing the key role of inverse modeling of experiments to derive optimum hydraulic properties and the importance of a future combination of noninvasive measurement techniques with inverse modeling by stochastic data fusion.

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“…Several authors have investigated different types of transient experiments and boundary conditions suited for a reliable estimation of soil hydraulic properties (e.g., van Dam et al, 1994;Šimůnek and van Genuchten, 1997;Inoue et al, 1998;Durner et al, 1999). Soil hydraulic properties are often estimated using inversion of one-step (Kool et al, 1985;van Dam et al, 1992) or multistep (Eching et al, 1994;van Dam et al, 1994) outflow experiments or controlled infiltration experiments (Hudson et al, 1996). Kool et al (1985) and Kool and Parker (1988) suggested that the transient experiments should cover a wide range of water contents to obtain a reliable estimation of the parameters.…”

Section: Introductionmentioning

confidence: 99%

Hydraulic and transport parameter assessment using column infiltration experiments

Younès¹,

Mara²,

Fahs³

et al. 2017

Hydrol. Earth Syst. Sci.

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Abstract. The quality of statistical calibration of hydraulic and transport soil properties is studied for infiltration experiments in which, over a given period, tracer-contaminated water is injected into an hypothetical column filled with a homogeneous soil. The saturated hydraulic conductivity, the saturated and residual water contents, the Mualem-van Genuchten shape parameters and the longitudinal dispersivity are estimated in a Bayesian framework using the Markov chain Monte Carlo (MCMC) sampler. The impact of the kind of measurement sets (water content, pressure inside the column, cumulative outflow and outlet solute concentration) and that of the solute injection duration is investigated by analyzing the calibrated model parameters and their confidence intervals for different scenarios. The results show that the injection period has a significant effect on the quality of the estimation, in particular, on the posterior uncertainty range of the parameters. All hydraulic and transport parameters of the investigated soil can be well estimated from the experiment using only the outlet concentration and cumulative outflow, which are measured non-intrusively. An improvement of the identifiability of the hydraulic parameters is observed when the pressure data from measurements taken inside the column are also considered in the inversion.

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Unsaturated Hydraulic Properties from Upward Flow into Soil Cores

Cited by 46 publications

References 0 publications

A hybrid global optimization method for inverse estimation of hydraulic parameters: Annealing‐Simplex Method

A hybrid global optimization method for inverse estimation of hydraulic parameters: Annealing‐Simplex Method

Determining Soil Hydraulic Properties

Hydraulic and transport parameter assessment using column infiltration experiments

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