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| Titel |
Estimating geostatistical parameters and spatially-variable hydraulic conductivity within a catchment system using an ensemble smoother |
| VerfasserIn |
R. T. Bailey, D. Baù |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1027-5606
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| Digitales Dokument |
URL |
| Erschienen |
In: Hydrology and Earth System Sciences ; 16, no. 2 ; Nr. 16, no. 2 (2012-02-02), S.287-304 |
| Datensatznummer |
250013164
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| Publikation (Nr.) |
 copernicus.org/hess-16-287-2012.pdf |
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| Zusammenfassung |
Groundwater flow models are important tools in assessing baseline conditions
and investigating management alternatives in groundwater systems. The
usefulness of these models, however, is often hindered by insufficient
knowledge regarding the magnitude and spatial distribution of the
spatially-distributed parameters, such as hydraulic conductivity (K), that
govern the response of these models. Proposed parameter estimation methods
frequently are demonstrated using simplified aquifer representations, when
in reality the groundwater regime in a given watershed is influenced by
strongly-coupled surface-subsurface processes. Furthermore, parameter
estimation methodologies that rely on a geostatistical structure of K often
assume the parameter values of the geostatistical model as known or estimate
these values from limited data.
In this study, we investigate the use of a data assimilation algorithm, the
Ensemble Smoother, to provide enhanced estimates of K within a catchment
system using the fully-coupled, surface-subsurface flow model CATHY. Both
water table elevation and streamflow data are assimilated to condition the
spatial distribution of K. An iterative procedure using the ES update
routine, in which geostatistical parameter values defining the true spatial
structure of K are identified, is also presented. In this procedure,
parameter values are inferred from the updated ensemble of K fields and used
in the subsequent iteration to generate the K ensemble, with the process
proceeding until parameter values are converged upon. The parameter
estimation scheme is demonstrated via a synthetic three-dimensional tilted
v-shaped catchment system incorporating stream flow and variably-saturated
subsurface flow, with spatio-temporal variability in forcing terms. Results
indicate that the method is successful in providing improved estimates of
the K field, and that the iterative scheme can be used to identify the
geostatistical parameter values of the aquifer system. In general, water
table data have a much greater ability than streamflow data to condition
K. Future research includes applying the methodology to an actual regional
study site. |
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