Basal conditions and glacier motion during the winter/spring transition, Worthington Glacier, Alaska, U.S.A

Joel T. Harper, Neil F. Humphrey, Mark C. Greenwood

Research output: Contribution to journalArticlepeer-review

Abstract

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 seasonal-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.

Original languageEnglish
Pages (from-to)42-50
Number of pages9
JournalJournal of Glaciology
Volume48
Issue number160
DOIs
StatePublished - 2002

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