Basal conditions and glacier motion during the winter/spring transition, Worthington Glacier, Alaska, U.S.A.
Observations of the motion and basal conditions of Worthington Glacier, Alaska, U.S.A., during late-winter and spring melt seasons revealed no evidence of a relationship between water pressure and sliding velocity. Measurements included borehole water levels (used as a proxy for basal water pressure...
| Published in: | Journal of Glaciology |
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| Main Authors: | , , |
| Format: | Text |
| Language: | unknown |
| Published: |
ScholarWorks at University of Montana
2002
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| Subjects: | |
| Online Access: | https://scholarworks.umt.edu/geosci_pubs/28 https://doi.org/10.3189/172756502781831629 https://scholarworks.umt.edu/context/geosci_pubs/article/1030/viewcontent/Basal_conditions_and_glacier_motion_during.pdf |
| Summary: | Observations of the motion and basal conditions of Worthington Glacier, Alaska, U.S.A., during late-winter and spring melt seasons revealed no evidence of a relationship between water pressure and sliding velocity. Measurements included borehole water levels (used as a proxy for basal water pressure), surface velocity, englacial deformation, sliding velocity, and time-lapse videography of subglacial water flow and bed characteristics. The boreholes were spaced 10-15 m apart; six were instrumented in 1997, and five in 1998. In late winter, the water-pressure field showed spatially synchronous fluctuations with a diurnal cycle. The glacier's motion was relatively slow and non-cyclic. In spring, the motion was characterized by rapid, diurnally varying sliding. The basal water pressure displayed no diurnal signal, but showed high-magnitude fluctuations and often strong gradients between holes. This transition in character of the basal water-pressure field may represent a seasonal evolution of the drainage system from linked cavities to a network of isolated patches and conduits. These changes occurred as the glacier was undergoing a season-velocity peak. The apparent lack of correlation between sliding velocity and water pressure suggests that local-scale water pressure does not directly control sliding during late winter or early in the melt season. |
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