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| Titel |
Hydrogeological settings of a volcanic island (San Cristóbal, Galapagos) from joint interpretation of airborne electromagnetics and geomorphological observations |
| VerfasserIn |
A. Pryet, N. d'Ozouville, S. Violette, B. Deffontaines, E. Auken |
| 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. 12 ; Nr. 16, no. 12 (2012-12-04), S.4571-4579 |
| Datensatznummer |
250013605
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| Publikation (Nr.) |
 copernicus.org/hess-16-4571-2012.pdf |
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| Zusammenfassung |
| Many volcanic islands face freshwater stress and the situation may worsen
with climate change and sea level rise. In this context, an optimum
management of freshwater resources becomes crucial, but is often impeded by
the lack of data. With the aim of investigating the hydrogeological settings
of southern San Cristóbal Island (Galapagos), we conducted a
helicopter-borne, transient electromagnetic survey with the SkyTEM
system. It provided unprecedented insights into the 3-D resistivity structure
of this extinct basaltic shield. Combined with remote sensing and fieldwork,
it allowed the definition of the first hydrogeological conceptual model of
the island. Springs are fed by a series of perched aquifers overlying a
regional basal aquifer subject to seawater intrusion. Dykes, evidenced by
alignments of eruptive cones at the surface, correspond to sharp sub-vertical
contrasts in resistivity in the subsurface, and impound groundwater in a
summit channel. Combined with geomorphological observations, airborne electromagnetics are shown to
be a useful for hydrogeological exploratory studies in complex, poorly
known environments. They allow optimal development of land-based geophysical
surveys and drilling campaigns. |
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