Barrier breach recovery in a lacustrine environment: Role of sediment supply and shoreline development

Abstract

Barrier breaching in response to high water levels and storm activity is common in the Laurentian Great Lakes of North America. Lacustrine breach recovery depends on the availability and transport of sediment from both alongshore and offshore sources and interannual variations in water levels. The recovery of two barrier breaches along the east coast of Point Pelee foreland, located on the north shore of Lake Erie, was monitored during a period of record high-water levels between 2016 and 2022. Despite both breaches developing during the same period, the southern breach (East Beach, EB) started to recover and close despite increasing water levels, while the northern breach (Hillman Marsh, HM) did not recover even as water levels fell below pre-breach levels. The opposing responses and hysteresis curves of the breaches are associated with differences in the availability of sediment from adjacent shorelines due to varying degrees of human impacts at each site. The increased sediment supply from more natural and diffusive shorelines adjacent to EB allowed for breach recovery, whereas a limited sediment supply from the highly fortified shoreline at HM prohibited breach recovery. If barrier recovery or reformation further landward is not possible, sensitive marsh habitat critical to migratory birds will be exposed to increasing wave energy, particularly as the extent and duration of lake ice decreases with climate change.