Stream hydrology controls on melt and surface morphology of debris-covered glaciers

Author: Eric Peterson, Geophysicist, Alaska Department of Natural Resources, Division of Geological & Geophysical Surveys; Regine Hock, and Michael Loso.

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Abstract

In this study of debris-covered Kennicott Glacier, Alaska, we investigate the influence of supraglacial stream hydrology on ice cliffs (which are melt hot spots) using in situ and remote sensed observations, streamflow measurements, and a conceptual geomorphic model. We found that 33% of ice cliffs (accounting for 69% of the total ice cliff area) are actively influenced by streams. Supraglacial streams contribute to ice cliff formation and maintenance by horizontal meandering, vertical incision, and debris transport. These processes produce an undercut lip at the ice cliff base and transport clasts up to tens of centimeters in diameter, preventing reburial of ice cliffs by debris. Stream meander morphology reminiscent of sedimentary river channel meanders and oxbow lakes produces sinuous and crescent ice cliff shapes. Stream avulsions result in rapid ice cliff collapse and local channel abandonment. Ice cliffs abandoned by streams are observed to be reburied by supraglacial debris, indicating a strong role played by streams in ice cliff persistence. The development of landscape evolution models may assist in quantifying the total net effect of these processes on ice cliff prevalence and melt from debris-covered glaciers, enhancing our ability to predict runoff from glacierized catchments.

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