Author(s)

K.S. Hari Prasad & M.S. Ghidaoui

Abstract

Inverse Problem for Transient Unsaturated Flow — Identifiability and Non Uniqueness K. S. Hari Prasad & M. S. Ghidaoui Department of Civil and Structural Engineering The Hong Kong University of Science and Technology Email : hari@wcmailust.hk & GHIDAOUI@usthk.ust.hk Abstract 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

Keywords