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| Titel |
The usefulness of outcrop-analogue air-permeameter measurements for analysing aquifer heterogeneity: testing outcrop hydrogeological parameters with independent borehole data |
| VerfasserIn |
B. Rogiers, K. Beerten, T. Smeekens, D. Mallants, M. Gedeon, M. Huysmans, O. Batelaan, A. Dassargues |
| 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 ; 17, no. 12 ; Nr. 17, no. 12 (2013-12-18), S.5155-5166 |
| Datensatznummer |
250086036
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| Publikation (Nr.) |
 copernicus.org/hess-17-5155-2013.pdf |
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| Zusammenfassung |
| Outcropping sediments can be used as easily accessible analogues for
studying subsurface sediments, especially to determine the small-scale
spatial variability of hydrogeological parameters. The use of cost-effective
in situ measurement techniques potentially makes the study of outcrop sediments
even more attractive. We investigate to what degree air-permeameter
measurements on outcrops of unconsolidated sediments can be a proxy for
aquifer saturated hydraulic conductivity (K) heterogeneity. The Neogene
aquifer in northern Belgium, known as a major groundwater resource, is used
as the case study. K and grain-size data obtained from different outcropping
sediments are compared with K and grain-size data from aquifer sediments
obtained either via laboratory analyses on undisturbed borehole cores (K and
grain size) or via large-scale pumping tests (K only). This comparison shows a
pronounced and systematic difference between outcrop and aquifer sediments.
Part of this difference is attributed to grain-size variations and earth
surface processes specific to outcrop environments, including root growth,
bioturbation, and weathering. Moreover, palaeoenvironmental conditions such
as freezing–drying cycles and differential compaction histories will further
alter the initial hydrogeological properties of the outcrop sediments. A
linear correction is developed for rescaling the outcrop data to the
subsurface data. The spatial structure pertaining to outcrops complements
that obtained from the borehole cores in several cases. The higher spatial
resolution of the outcrop measurements identifies small-scale spatial
structures that remain undetected in the lower resolution borehole data.
Insights in stratigraphic and K heterogeneity obtained from outcrop sediments
improve developing conceptual models of groundwater flow and transport. |
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