Inverse Problem For Transient Unsaturated Flow — Identifiability And Non Uniqueness

In the present study, the identifiability and non uniqueness of soil hydraulic properties in unsaturated flow systems are discussed. Necessary and sufficient conditions for identifiability are derived. A parameter estimation algorithm is developed by combining the Adjoint State Theory with Conjugate...

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Bibliographic Details
Published in:WIT Transactions on Ecology and the Environment 1998-01, Vol.23
Main Authors: K.S. Hari Prasad, Ghidaoui, M S
Format: Article
Language:English
Subjects:
Algorithms
Conjugate gradient method
Conjugates
Hydraulic properties
Inverse problems
Parameter estimation
Parameter identification
Soil properties
Uniqueness
Unsaturated flow
Unsaturated soils
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Summary:In the present study, the identifiability and non uniqueness of soil hydraulic properties in unsaturated flow systems are discussed. Necessary and sufficient conditions for identifiability are derived. A parameter estimation algorithm is developed by combining the Adjoint State Theory with Conjugate Gradient Method and Levenberg-Marquardt method. These two methods are compared through few numerical examples. It is shown that Levenberg-Marquardt algorithm is superior to Conjugate Gradient Method. However, Levenberg-Marquardt algorithm also fails to converge to the global minimum when the initial guess parameters are far from the true values. Introduction Moisture flow through the unsaturated
ISSN:1746-448X
1743-3541
DOI:10.2495/CMWR980391