Calibration and Reliability in Groundwater Modelling: Credibility of Modelling

(Proceedings of ModelCARE 2007 Conference, held in Denmark, September 2007). IAHS Publ. 320, 2008, 284-288.

Global upscaling of hydraulic conductivity for modelling contaminant transport in groundwater

NE-ZHENG SUN^1,2 & WILLIAM W.-G. YEH²

1 Department of Applied Mathematics, Shandong University, Jinan, Shandong Province, China

nezheng@ucla.edu

2 Civil & Environmental Engineering Department, University of California, Los Angeles, California 90095, USA

Abstract Mass transport in groundwater is strongly dependent on the small-scale heterogeneity. Upscaling may cause inaccurate characterization of contaminant plumes. In this paper we do not attempt to accurately characterize a contaminant plume; instead, we are interested in finding a representative hydraulic conductivity at the global scale for specified objectives of model application. Examples of specific objectives in water quality management include the prediction of arrival time, the estimation of peak concentration, and the assessment of remediation alternatives. A reliable representative hydraulic conductivity can be obtained by solving a generalized inverse problem when data are sufficient. The sufficiency of data can be tested by the worst-case-parameter (WCP). Numerical examples show that the WCP for mass transport problems still has a cluster structure, but its shape may become more complex. Generally, constructing an objective-oriented mass transport model requires more data than constructing an objective-oriented groundwater flow model.

Key words heterogeneous aquifer; parameter identification; mass transport; experimental design; robustness