The Impact of a Shrinking Cryosphere on the Form of Arctic Alluvial Channels

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A shrinking cryosphere has important implications for the geomorphology of alluvial channels in arctic catchments because ice and permafrost alter the driving and resisting forces responsible for shaping local channel cross sections. For example, bedfast ice in shallow channels can suppress bedload transport during snowmelt events causing a reduction in the frequency of geomorphically effective flows, while cap ice in deeper channels can alter stream hydraulics. The impact of these local controls on catchment-scale geomorphic patterns, however, is less certain. A case study of one arctic river in northern Alaska, USA, reveals hydraulic geometry anomalies that can be reasonably explained by the influence of ice and permafrost on local channel form. However, there is a critical lack of data from rivers wholly contained in the continuous permafrost zone preventing comprehensive understanding of how arctic rivers might respond in a shrinking cryosphere.