Campus Units

Geological and Atmospheric Sciences

Document Type

Article

Publication Version

Published Version

Publication Date

11-2018

Journal or Book Title

Journal of Geophysical Research: Earth Surface

Volume

123

Issue

11

First Page

2863

Last Page

2877

DOI

10.1029/2018JF004680

Abstract

The subglacial processes of abrasion and quarrying are thought to be primarily responsible for bedrock erosion by glaciers. While theory points to sliding speed as the dominant control on abrasion, rates of quarrying are likely scaled by a more complex combination of sliding speed, effective pressure, bed roughness, and short‐term water‐pressure fluctuations. Here we pair a model for quarrying based on statistical characterization of bedrock strength with a model for subglacial hydrology that describes the temporal evolution of cavities under the influence of variations in sliding speed and effective pressure. Using a finite element model, we simulate the evolution of the hydrological system at the base of a glacier and compute rates of abrasion and quarrying. Cavity lengths and channel cross sections evolve through time, causing temporal shifts in ice‐bed contact area, which in turn govern the differential stress that influences erosion over the course of a year. Our results demonstrate how variations in meltwater production amplify rates of subglacial erosion relative to the case of steady meltwater generation. The level of amplification depends on how the variations control the ice‐bed contact area. Seasonal variations are most effective in boosting mean rates of basal sliding and hence subglacial abrasion, whereas shorter‐term variations (monthly‐weekly) most strongly influence rates of subglacial quarrying through temporal amplification of differential bedrock stress around cavities. This influence of transient hydrology on subglacial erosion processes may explain why glaciers in temperate climates with strong variations in temperature and precipitation erode faster than similar‐type glaciers in polar environments.

Comments

This article is published as Ugelvig, S. V., D. L. Egholm, R. S. Anderson, and N. R. Iverson. "Glacial Erosion Driven by Variations in Meltwater Drainage." Journal of Geophysical Research: Earth Surface 123, no. 11 (2018): 2863-2877. DOI: 10.1029/2018JF004680. Posted with permission.

Copyright Owner

American Geophysical Union

Language

en

File Format

application/pdf

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