On parameterization of the inverse problem for estimating aquifer properties using tracer data
In developing a reliable approach for inferring hydrological properties through inverse modeling of tracer data, decisions made on how to parameterize heterogeneity (i.e., how to represent a heterogeneous distribution using a limited number of parameters that are amenable to estimation) are of param...
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Published in | Water resources research Vol. 48; no. 6 |
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Main Authors | , , , , , , , , |
Format | Journal Article |
Language | English |
Published |
Washington
Blackwell Publishing Ltd
01.06.2012
John Wiley & Sons, Inc |
Subjects | |
Online Access | Get full text |
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Summary: | In developing a reliable approach for inferring hydrological properties through inverse modeling of tracer data, decisions made on how to parameterize heterogeneity (i.e., how to represent a heterogeneous distribution using a limited number of parameters that are amenable to estimation) are of paramount importance, as errors in the model structure are partly compensated for by estimating biased property values during the inversion. These biased estimates, while potentially providing an improved fit to the calibration data, may lead to wrong interpretations and conclusions and reduce the ability of the model to make reliable predictions. We consider the estimation of spatial variations in permeability and several other parameters through inverse modeling of tracer data, specifically synthetic and actual field data associated with the 2007 Winchester experiment from the Department of Energy Rifle site. Characterization is challenging due to the real‐world complexities associated with field experiments in such a dynamic groundwater system. Our aim is to highlight and quantify the impact on inversion results of various decisions related to parameterization, such as the positioning of pilot points in a geostatistical parameterization; the handling of up‐gradient regions; the inclusion of zonal information derived from geophysical data or core logs; extension from 2‐D to 3‐D; assumptions regarding the gradient direction, porosity, and the semivariogram function; and deteriorating experimental conditions. This work adds to the relatively limited number of studies that offer guidance on the use of pilot points in complex real‐world experiments involving tracer data (as opposed to hydraulic head data).
Key Points
Decisions on parameterization of heterogeneity are crucial for inverse modeling
We aim to quantify and highlight how such decisions affect inversion results
Study involves inverse modeling of synthetic and field data from DOE Rifle site |
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Bibliography: | ArticleID:2011WR011203 istex:BD75C432144C396A26956235A290164D821EAA3C ark:/67375/WNG-7GPQR452-6 Tab-delimited Table 1.Tab-delimited Table 2.Tab-delimited Table 3.Tab-delimited Table 4.Tab-delimited Table 5. USDOE AC05-76RL01830 PNNL-SA-82457 |
ISSN: | 0043-1397 1944-7973 |
DOI: | 10.1029/2011WR011203 |