Rates of bluff retreat and shoreline change along the north shore of Lake Erie

Increasing shoreline development, changes in water levels, storm activity, and reduced lake ice has resulted in accelerated shoreline erosion around the Laurentian Great Lakes (LGL). Along the northern shore of Lake Erie, retreat of glacial bluffs threatens sensitive habitats, infrastructure, and personal property. This study quantifies the extent of modern shoreline change and bluff retreat along 186 km of beach and 109 km of bluffs in the north central basin of Lake Erie between 2006 and 2020. Shoreline change and bluff retreat were quantified using imagery from the Southwestern Ontario Orthophotography Project (SWOOP) and digital elevation model datasets for 2006, 2010, 2015, and 2020. Results suggest that the average rate of bluff toe and brink retreat were −1.75 m y -1 and −1.56 m y -1 , respectively, but with significant variation in retreat alongshore and in response to variations in water level. The corresponding alongshore average annual volumetric loss from the bluffs was 43.23 × 10 5 m 3 y -1 . Over the same period, a total of ∼ 2.6 × 10 6 m 3 y -1 of sediment was lost on the updrift side of the jetties, suggesting that jetties are at capacity and that sediment is bypassing them. Despite the liberation of large amounts of sediment from the bluffs and from behind the jetties, the shoreline continued to erode along the distal spits, suggesting that sediment is being transported offshore or beyond the distal ends of the spits. Further study is required to determine the current and future fate of the bluff sediment as part of a regional sediment budget.