Calibration and Reliability in Groundwater Modelling: Credibility of Modelling

(Proceedings of ModelCARE 2007 Conference, held in Denmark, September 2007). IAHS Publ. 320, 2008, 58-63.

Credibility evaluation of numerically estimated heterogeneous hydraulic property by eigenvalues of Hessian of Lagrange function for constrained groundwater problem

K. Masumoto

Department of Geoscience, Interdisciplinary Faculty of Science and Engineering, Shimane University,
1060 Nishikawatsu, Matsue, Shimane 690-8504, Japan

masu@riko.shimane-u.ac.jp

Abstract The problem of the inversion analysis of a heterogeneous hydraulic property can be formulated as a nonlinear optimization problem with many constrained conditions, and the validity of the solution, the uniqueness and sensitivity, can be examined theoretically. For the purpose of evaluating the credibility of the results from numerical inversion, the author calculated eigenvalues of Hessian of Lagrange function for the nonlinear constrained problem of simple one- and two-dimensional groundwater models. Transient head data at multiple points were assumed to be observed. The results show that using different data sets or different parameter settings caused different credibility indices defined by the eigenvalues, and they show good correspondence to the accuracy of the estimated parameters.

Key words heterogeneous; hydraulic property; inversion; transient flow; credibility index