Seasonal Arctic Coastal Bluff Dynamics in Adventfjorden, Svalbard

The geomorphic development of mixed‐type coasts, which consist of bedrock cliffs overlain by unconsolidated sediment, is poorly known in the Arctic but important for addressing long‐term coastal responses and potential socio‐economic implications of climate change. At Vestpynten, Svalbard, ground temperatures, erosion rates and thermo‐denudation processes along a 100 m coastal transect were recorded between May 2012 and August 2014 using thermistor strings, time‐lapse photography and visual observation. The results indicate that mixed‐type coasts oscillate between periods of active bluff recession (lasting from weeks to months) and stability (lasting from months to years). Thermo‐denudation and nivation processes are the main erosional agents during periods of active recession. The highest rates of coastal bluff crest recession (50 and 20 cm in 2012 and 2013, respectively) were observed mainly in June. Erosion was closely related to the melting of a snow bank that accumulates on the lee side of the coastal bluff in winter. Waves acted only to remove material accumulated in scree slopes at the base of the coastal bluff, and were most effective in summer and autumn. Factors controlling the erosion of mixed‐type coasts in Svalbard include the relative position/elevation of bedrock and the occurrence of snow banks in winter. Copyright © 2016 John Wiley & Sons, Ltd.