Terrestrial processes affecting unlithified coastal erosion disparities in central fjords of svalbard

Abstract

Terrestrial influences of coastal cliff morphology and hydrological impact on coastal erosion in unlithified cliff sediments in the inner fjords of Svalbard are assessed. Differential global positioning system measurements have been taken annually over the past two to four years at four field sites in central Svalbard. Measurements were combined with aerial imagery using ArcGIS and the Digital Shoreline Analysis System to calculate rates of erosion in varying geomorpho-logical cliff types. A total of 750 m of coast was divided into two main cliff types: ice-poor and ice-rich tundra cliffs and further divided based on their sediment depositional character and processes currently acting upon sediments. The results show that the most consistent erosion rates occur in the ice-poor cliffs (0.34 m/yr), whereas the most irregular and highest rates occur in ice-rich cliffs (0.47 m/yr). Throughout the study, no waves were observed to reach cliff toes, and therefore erosion rates are considered to reflect an effect of terrestrial processes, rather than wave action. Terrestrial hydrological processes are the driving factors for cliff erosion through winter precipitation for ice-poor cliffs and summer precipitation for ice-rich cliffs. Sediment removal from the base of the cliffs appears to be mainly conducted by sea ice and the ice foot during break up as waves did not reach the base of the studied cliffs during the observed period.