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| Titel |
Monitoring water accumulation in a glacier using magnetic resonance imaging |
| VerfasserIn |
C. Vincent, J. M. Baltassat, J. F. Girard, E. Thibert, O. Gagliardini, Marc Descloitres, A. Gilbert, S. Garambois, A. Chevalier, H. Guyard |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1994-0416
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| Digitales Dokument |
URL |
| Erschienen |
In: The Cryosphere ; 8, no. 1 ; Nr. 8, no. 1 (2014-01-28), S.155-166 |
| Datensatznummer |
250116013
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| Publikation (Nr.) |
 copernicus.org/tc-8-155-2014.pdf |
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| Zusammenfassung |
| Tête Rousse is a small polythermal glacier located in the Mont Blanc area
(French Alps) at an altitude of 3100 to 3300 m. In 1892, an outburst flood
from this glacier released about 200 000 m3 of water mixed with ice,
causing much damage. A new accumulation of melt water in the glacier was not
excluded. The uncertainty related to such glacier conditions initiated an
extensive geophysical study for evaluating the hazard. Using
three-dimensional surface nuclear magnetic resonance imaging (3-D-SNMR), we
showed that the temperate part of the Tête Rousse glacier contains two
separate water-filled caverns (central and upper caverns). In 2009, the
central cavern contained about 55 000 m3 of water. Since 2010, the
cavern is drained every year. We monitored the changes caused by this pumping
in the water distribution within the glacier body. Twice a year, we carried
out magnetic resonance imaging of the entire glacier and estimated the volume
of water accumulated in the central cavern. Our results show changes in
cavern geometry and recharge rate: in two years, the central cavern lost
about 73% of its initial volume, but 65% was lost in one year after
the first pumping. We also observed that, after being drained, the cavern was
recharged at an average rate of 20 to 25 m3 d−1 during the winter
months and 120 to 180 m3 d−1 in summer. These observations
illustrate how ice, water and air may refill englacial volume being emptied
by artificial draining. Comparison of the 3-D-SNMR results with those
obtained by drilling and pumping showed a very good correspondence,
confirming the high reliability of 3-D-SNMR imaging. |
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