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An Analysis of Bias in Groundwater Modelling Due to the Interpretation of Site Characterization Data

Published online by Cambridge University Press:  03 September 2012

K. J. Clark ,
T. Ikeda ,
M. D. Impey ,
T. McEwen  and
M. White
K. J. Clark
Affiliation:
QuantiSci Ltd, Chiltern House, 45 Station Rd, Henley-on-Thames, Oxon, RG9 1AT, UK, [email protected]
T. Ikeda
Affiliation:
JGC Corporation, Yokohama, Japan.
M. D. Impey
Affiliation:
QuantiSci Ltd, Chiltern House, 45 Station Rd, Henley-on-Thames, Oxon, RG9 1AT, UK, [email protected]
T. McEwen
Affiliation:
QuantiSci Ltd, Melton Mowbray, Leics, UK, [email protected]
M. White
Affiliation:
QuantiSci Ltd, Melton Mowbray, Leics, UK, [email protected]
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Abstract

Bias is a difference between model and reality. Bias can be introduced at any stage of the modelling process during a site characterisation or performance assessment programme. It is desirable to understand such bias so as to be able to optimally design and interpret a site characterisation programme. The objective of this study was to examine the source and effect of bias due to the assumptions modellers have to make because reality cannot be fully characterised in the prediction of ground-water fluxes. A well-defined synthetic “reality” was therefore constructed for this study. A limited subset of these data were independently interpreted and used to compute groundwater fluxes across specified boundaries in a cross section. The modelling results were compared to the “true” solutions derived using the full dataset. This study clarified and identified the large number of assumptions and judgements which have to be made when modelling a limited site characterisation dataset. It is concluded that bias is introduced at each modelling stage, and that it is not necessarily detectable by the modellers even if multiple runs with varied parameter values are undertaken.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 465: Symposium II – Scienfific Basis for Nuclear Waste Management XX , 1996 , 1125
Copyright
Copyright © Materials Research Society 1997

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References

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