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| Titel |
How do soil types affect stable isotope ratios of 2H and 18O under evaporation: A Fingerprint of the Niipele subbasin of the Cuvelai - Etosha basin, Namibia. |
| VerfasserIn |
Marcel Gaj, Matthias Beyer, Josefina Hamutoko, Shoopi Uugulu, Heike Wanke, Paul Koeniger, Christoph Kuells, Christoph Lohe, Thomas Himmelsbach |
| 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 |
250091588
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| Publikation (Nr.) |
 EGU/EGU2014-5890.pdf |
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| Zusammenfassung |
| Northern Namibia is a region with high population growth, limited water resources and a
transboundary aquifer system where groundwater recharge and groundwater flow processes
are not well understood. This study is an interdisciplinary approach within the frame of
SASSCAL (Southern African Science Service Centre for Climate Change and Adaptive Land
Management) to improve the understanding of links between hydrological, geochemical and
ecological processes to locate areas that contribute to recharge a shallow aquifer system in the
Cuvelai-Etosha basin.
Results of a field campaign are presented, conducted in November 2013 which is the first of a
series planned between the years 2013 and 2016. Soil samples were taken in the semi–arid
subbasin of the Cuvelai Etosha surface water basin before the rainy season. Potential
evaporation, temperature measurements and infiltration tests were performed at two sites with
different soil characteristics. Soil samples were taken under natural conditions to a maximum
depth of 4 meters. Additionally to environmental isotope signals (stable isotopes 2H, and 18O
and water of known isotopic composition (local groundwater) has been applied to the
same plots. Soil samples were taken to a depth of 1 m with an interval of 10 cm
after 24 and 48 hours for an investigation of evaporation impact on stable isotope
ratios.
The soil water is extracted cryogenically from the soil samples in the laboratory and
subsequently analyzed using a Picarro L2120-i cavity-ringdown (CRD) water vapor analyzer
after vaporization. Results of the direct measurement of different soil types indicate that
evaporation from a saturated soil can exceed potential evaporation from an open water
surface1. This implies, alternative methods are needed for the determination of evaporation
which will be discussed here.
1Brutsaert W.; Parlanget M.B. (1998): Hydrologic cycle explains the evaporation
paradox. In: Nature (396), p. 30. |
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