Multi-decadal coastal evolution of a North Atlantic shelf-edge vegetated sand island – Sable Island, Canada

• Main Authors: Eamer, Jordan B.R., Didier, David, Kehler, Dan, Manning, Ian, Colville, David, Manson, Gavin K., Jagot, Alexandre, Kostylev, Vladimir
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: University of Toronto 2021
• Subjects: Barrier Island; Canada; North Beach; North Atlantic
• Online Access: http://hdl.handle.net/1807/108067; http://www.nrcresearchpress.com/doi/abs/10.1139/cjes-2020-0194

Impacts from a changing climate, in particular sea-level rise, will be most acutely felt on small oceanic islands. A common configuration of mid-latitude islands is the sandy barrier island. Sable Island, Nova Scotia, Canada is a vegetated sand island near the shelf edge, 160 km from the nearest point of land, that is morphologically similar to a barrier island. This study uses 60 years of airphoto records to analyse changes in coastline position through digitized shore and vegetation (foredune proxy) lines. Rates of coastal movement are analysed to model the future (2039) coastal configuration. The analyses suggest that the majority of the coastline on Sable Island is in retreat, with net retreat on the south side of the island only partially offset by modest net advance on the north side. The different morphologies of the beach-dune systems of South and North Beach, driven by incident wind and waves, yield these different coastline responses. Projected loss of 10 ha by 2039 of the climax heath vegetative community to shoreline retreat suggests a trend toward island instability due to coastline migration. Island-wide dataset trends show support for two different but complementary hypotheses about whole-island evolution: either the island is mobile via bank migration driving southern coastline changes and experiencing sediment transport toward the east, or the island is generally immobile and losing subaerial sediments (and thus shrinking) likely due to ongoing (and accelerating) sea-level rise. The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author.