The impact of low ice cover on shoreline recession: A case study from Western Point Pelee, Canada

The western shore of Point Pelee National Park (PPNP) in Ontario, Canada, exhibited high recession rates in the winter of 2005/2006. During the period 1959–2004, the western side of the park generally exhibited accretion, attributed to longer duration of ice coverage during winter and favorable topography and sedimentary conditions in comparison to the eastern side. Compared to the winter of 2003/2004, changes in Lake Erie water levels, winter wind regime and human-made structures and interferences were negligible during 2004–2006 within the Colchester-to-Southeast Shoal littoral cell in western Lake Erie, where PPNP is located. However, the winter of 2005/2006 exhibited overall low ice cover conditions unlike the typical freeze-up conditions in western Lake Erie. The 2006 high recession rates on the western shore of Point Pelee are attributed to the low ice cover conditions in the winter of 2005/2006. While less-than-average ice cover does not in its own cause erosion, in certain areas it increases the opportunity for sediment removal by waves by removing a significant source of protection during winter. The episode illustrates the potential impacts of ice-free and low ice cover winters on the western shore of Point Pelee and shores under similar conditions. Future climate change patterns are expected to result in shorter ice-durations and more frequent ice-free winters in the western basin of Lake Erie, exposing western PPNP to wave action during the winter season and resulting in increased erosion. The increased opportunity for shore erosion will negatively impact ecologically and economically viable spaces in PPNP.

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► Western shore of Point Pelee is typically an accreting shoreline.
► The shore exhibited high recession rates in winter 2006.
► Ice cover forms during winter, protecting Point Pelee shores from winter storms.
► Winter 2006 was mild with little ice cover, providing opportunity for erosion.
► The episode illustrates conditions under which winter ice cover protects shores.