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| Titel |
Compiling geophysical and geological information into a 3-D model of the glacially-affected island of Föhr |
| VerfasserIn |
T. Burschil, W. Scheer, R. Kirsch, H. Wiederhold |
| 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. 10 ; Nr. 16, no. 10 (2012-10-01), S.3485-3498 |
| Datensatznummer |
250013509
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| Publikation (Nr.) |
 copernicus.org/hess-16-3485-2012.pdf |
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| Zusammenfassung |
Within the scope of climatic change and associated sea level rise, coastal
aquifers are endangered and are becoming more a focus of research to ensure the
future water supply in coastal areas. For groundwater modelling a good
understanding of the geological/hydrogeological situation and the aquifer
behavior is necessary. In preparation of groundwater modelling and
assessment of climate change impacts on coastal water resources, we setup a
geological/hydrogeological model for the North Sea Island of Föhr.
Data from different geophysical methods applied from the air, the surface
and in boreholes contribute to the 3-D model, e.g. airborne electromagnetics
(SkyTEM) for spatial mapping the resistivity of the entire island, seismic
reflections for detailed cross-sections in the groundwater catchment area,
and geophysical borehole logging for calibration of these measurements. An
iterative and integrated evaluation of the results from the different
geophysical methods contributes to reliable data as input for the 3-D model
covering the whole island and not just the well fields.
The complex subsurface structure of the island is revealed. The local
waterworks use a freshwater body embedded in saline groundwater. Several
glaciations reordered the youngest Tertiary and Quaternary sediments by
glaciotectonic thrust faulting, as well as incision and refill of glacial
valleys. Both subsurface structures have a strong impact on the distribution
of freshwater-bearing aquifers. A digital geological 3-D model
reproduces the hydrogeological structure of the island as a base for a
groundwater model. In the course of the data interpretation, we deliver a
basis for rock identification.
We demonstrate that geophysical investigation provide petrophysical
parameters and improve the understanding of the subsurface and the
groundwater system. The main benefit of our work is that the successful
combination of electromagnetic, seismic and borehole data reveals the
complex geology of a glacially-affected island. A sound understanding of the
subsurface structure and the compilation of a 3-D model is imperative and the
basis for a groundwater flow model to predict climate change effects on
future water resources. |
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