Multiple Parameterization for Hydraulic Conductivity Identification
Article first published online: 30 JUL 2008
© 2008 The Author(s) Journal compilation © 2008 National Ground Water Association
Volume 46, Issue 6, pages 851–864, November–December 2008
How to Cite
Tsai, F. T.-C. and Li, X. (2008), Multiple Parameterization for Hydraulic Conductivity Identification. Ground Water, 46: 851–864. doi: 10.1111/j.1745-6584.2008.00478.x
- Issue published online: 23 OCT 2008
- Article first published online: 30 JUL 2008
- Received August 2007, accepted May 2008.
Hydraulic conductivity identification remains a challenging inverse problem in ground water modeling because of the inherent nonuniqueness and lack of flexibility in parameterization methods. This study introduces maximum weighted log-likelihood estimation (MWLLE) along with multiple generalized parameterization (GP) methods to identify hydraulic conductivity and to address nonuniqueness and inflexibility problems in parameterization. A scaling factor for information criteria is suggested to obtain reasonable weights of parameterization methods for the MWLLE and model averaging method. The scaling factor is a statistical parameter relating to a desired significance level in Occam’s window and the variance of the chi-squares distribution of the fitting error. Through model averaging with multiple GP methods, the conditional estimate of hydraulic conductivity and its total conditional covariances are calculated. A numerical example illustrates the issue arising from Occam’s window in estimating model weights and shows the usefulness of the scaling factor to obtain reasonable model weights. Moreover, the numerical example demonstrates the advantage of using multiple GP methods over the zonation and interpolation methods because GP provides better models in the model averaging method. The methodology is applied to the Alamitos Gap area, California, to identify the hydraulic conductivity field. The results show that the use of the scaling factor is necessary in order to incorporate good parameterization methods and to avoid a dominant parameterization method.