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

Abstract

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.

Shoreline change rates and land to sea sediment and soil organic carbon transfer in eastern Parry Peninsula from 1965 to 2020 (Amundsen Gulf, Canada)

“…Our comparative analysis has shown that the shoreline changes and volume transfer estimates can be very different depending on the shoreline proxy used -backshore vs. foreshore. Eamer et al, (2021) draw similar conclusions in a comparative analysis of changes between waterline and vegetation marks, finding poor correlation between the proxies and differences in coastline evolution.…”

Morphologic, Atmospheric, and Oceanic Drivers Cause Multi‐Temporal Saltwater Intrusion on a Remote, Sand Island

“…In general, our findings highlight the control of island topography on Sable Island's freshwater lens and indicate erosion is a primary driver of fresh groundwater decline. Prevailing ocean currents and coastal storms have resulted in a gradual shift in the island toward the northeast and significant erosion of the south dune (Eamer et al., 2022). With continuous erosion, the freshwater lens is constantly in disequilibrium with the island morphology, and changes in the freshwater lens observed in geophysical surveys lag morphologic change, consistent with numerical modeling results (Schneider & Kruse, 2006).…”

The impact of coastal erosion on the archaeology of the Cyrenaican coast of Eastern Libya

“…2032 and 2042 in this case). Analogous studies have been completed elsewhere for coastal management purposes [81][82][83][84][85][86] and for cultural heritage vulnerability assessment [87]. For this study, the forecasting tool was applied only to the LRR derived from VHR shorelines for the last decade.…”