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| Titel |
Aquifer characterization using geoelectrical modelling, a case study |
| VerfasserIn |
Rena Meyer, Martin Sauter, Andreas Weller |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250089303
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| Publikation (Nr.) |
 EGU/EGU2014-3503.pdf |
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| Zusammenfassung |
| Surface geophysical investigations offer inexpensive and complementary information for
hydrogeological issues. The quality and feasibility of geophysical models can be
improved considerably by incorporating geological and hydrogeological a-priori
information.
In the presented study, densely spaced surface geoelectrical measurements were
performed at the hydrogeological testsite Stegemühle, Göttingen, Germany. Twelve parallel
profiles, 100 m long, with an electrode spacing of 0.5 m were measured using the
averaged half Wenner configuration. The study area consists of a gravel-sand partially
confined aquifer. Thanks to former studies a good hydraulic and geological data base is
available.
Vertical electrical soundings (VES) as well as 2D and 3D inversions were carried out with
the purpose of building a subsurface resistivity model of the aquifer. Commercial software
(res2/3Dinv) as well as non-commercial inversion algorithms (VES4, AC2DSIRT) are
applied for data analysis. The interpretation of geoelectrical models generally suffers an
ambiguity due to the principle of equivalence that hinders the independent determination of
layer resistivity and thickness. To overcome this problem, information from certain
borehole profiles and conductivity logs were included to calibrate VES and constrain
AC2DSIRT modelling. Inversions using AC2DSIRT with an initial model according to the
calibrated results of VES generate a 2D resistivity distribution that is significantly more
feasible in terms of root mean square and geological data than those without any
constraints.
Apart from this, a field specific linear relationship between electrical resistivity and
hydraulic conductivity is determined at six well locations. This relation is used to extrapolate
the hydraulic conductivity distribution over the whole study area.
In conclusion, the presented field study shows the importance of integration of a-priori
geological and hydrological information to improve the output of geoelectrical inversions and
to minimize the ambiguity in data interpretation. The derived relationship of electrical and
hydraulic parameters serves as a suitable way for a reliable aquifer characterization. |
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