Coastal Erosion in PEI

By Grace Robertson, NSEN Journalism Volunteer

Most of my life has been spent living along the coast of Atlantic Canada in the small town of Souris, Prince Edward Island (PEI); a region admired for its lush fields, ocean views, and especially the rust-red sandstone cliffs and fine sand beaches. I was raised here, it’s home. But year by year, piece by piece, I’ve watched it chip away, the endless torrent of wind and waves eroding our borders and pulling more and more of our island into the sea. Properties are becoming smaller, and houses are creeping ever closer to the ledge. An average of 0.28 meters of land is eroded from the island every year, putting over 1000 residences, 17 lighthouses, and nearly 45 km of roads at risk (Fenech et al., 2017).

As the climate continues to change, places like PEI are particularly at risk. Sandstone is a very fragile sedimentary rock that is highly susceptible to erosion under typical conditions, but what the world is currently experiencing is far from typical. Globally, there has been an increase of approximately 75% in the number of category 4 and 5 hurricanes, and eastern Canada is not immune (Thompson et al., 2009). In the higher latitudes of the northern hemisphere, including eastern Canada, the frequency of powerful storms has been increasing over the past 50-100 years and the number of hurricanes was above normal in 9 of the 11 years leading up to 2009 (Keim et al., 2004; Thompson et al., 2009).

In addition to this, the rate of sea level rise has been increasing dramatically compared to natural levels. Sea level stabilized between 3000 and 2000 years ago after rising a total of 120 m as we transitioned out of the last ice age, but in the late 19th century, the sea began to rise again. The first half of the 20th century had an estimated sea level rise of 1.7 mm/y but that has since increased to 3 mm/y (Bindoff et al., 2007). Areas like the Gulf of Saint Lawrence, in which PEI sits, are particularly vulnerable to this sea level rise because it will amplify the frequency of storm surges that attack our coasts and flood our lands washing away pieces of the island with them.

These impacts were recently observed after PEI was assaulted by Hurricane Fiona in late September of this year. Fiona did years worth of erosional damage in a single night and pulled away almost 10 meters of the dunes in some areas of Cavendish and Brackley Beach (Figure 1) (Logan, 2022; Yarr, 2022). 

Resulting shoreline erosion from Hurricane Fiona on Cavendish and Brackley Beach in PEI (Logan, 2022; Yarr, 2022). 

These impacts have also weakened our coastlines by removing important vegetation whose root systems we rely on to help hold the dunes together (Silliman et al., 2019). Although some of removed sediment will be able to reaccumulate over time, there was also a lot of material pulled too far out to sea to have a chance of being carried back in with the current (Figure 2). Also, as storms continue to get more frequent and violent going forward, it is unlikely our shores will have sufficient amounts of time to recover their sediments and vegetation between these weather events (Logan, 2022).

Photographs of PEI taken by satellite on August 21st (left) before hurricane Fiona, and September 25th (right) after the hurricane demonstrating the amount of sediment removed from the province (Canadian Space Agency, 2022).

It is obvious that something needs to be done to protect the shoreline of PEI. Some common types of protection used in erosion sensitive areas include hard armour structures such as breakwaters (rock and rubble mounds places in front of the shore), groynes (perpendicular lines of material such as rock, wood, steel, rubble, or sand bags), and revetments (a wall of stone or concrete placed along an embankment) (Anastasiou & Sylaios, 2016; Groynes, Breakwaters and Artificial Reefs, n.d.; “Revetment,” n.d.). Although these are effective at blocking wave energy from removing more of the coastline and/or allow for more accretion of sediments, they usually have adverse effects on adjacent areas of the coast by causing them to experience greater erosion, and significant erosion is typically observed around the edges of these structures (Anastasiou & Sylaios, 2016). In addition to this, many rural communities simply do not have the financial capacity to implement such protective structures, but this unfortunately also means they do not have the funds to relocate houses and other structures (Vasseur et al., 2017). 

A better and more natural method of protecting our coasts is to use living shorelines. In this method, native vegetation is planted along the shorelines to help hold sediments in place with their roots as well as capture materials being carried by the wind (Silliman et al., 2019). Unlike hard armour structures which are strongest on the first day they are implemented and become weaker over time, living shorelines are weakest initially and become stronger as their root systems develop and plants mature. This makes living shorelines a more effective long-term solution. We can make use of this technique in PEI by planting native species along the dunes and cliff regions to strengthen them against unfavourable weather conditions that are most certainly coming out way in the future.

Although we have these protection options available for the inevitable climatic events we are going to face, it is also extremely important that we make changes to limit our impacts on the island’s coastal erosion both directly and indirectly going forward. Studies have shown that human disturbances such as driving on beaches and walking on unauthorized areas like dunes significantly reduces vegetation cover in coastal habitats (Delgado-Fernandez et al., 2019), suggesting that these area will be weakened against erosional forces. It is therefore critical that human disturbances be controlled in the future to allow for more abundant vegetation and to give living shorelines a better chance of success if they become more widely implemented going forward. Furthermore, we must make changes to limit the rate of climate change the world is experiencing. Even if we strengthen our coasts, storms are strengthening too, and the sea level continues to creep higher. Greenhouse gas emissions need to be reduced in order to lessen the rate of global warming that has resulted in the observed alterations in climate. Now is the time to take action- PEI depends on it.

References

Anastasiou, S., & Sylaios, G. (2016). Assessment of Shoreline Changes and Evaluation of Coastal Protection Methods to Mitigate Erosion. Coastal Engineering Journal, 58(2), 1650006-1-1650006–1650024. https://doi.org/10.1142/S0578563416500066

Bindoff, N., Willebrand, J., Artale, V., Cazenave, A., Gregory, J., Gulev, S., Hanawa, K., Le Quéré, C., Levitus, S., Nojiri, Y., Shum, C. K., Talley, L., & Alakkat, U. (2007). Observations: Oceanic Climate Change and Sea Level. The Physical Science Basis. Working Group I Contribution to the Intergovernmental Panel on Climate Change Fourth Assessment Report.

Delgado-Fernandez, I., O’Keeffe, N., & Davidson-Arnott, R. G. D. (2019). Natural and human controls on dune vegetation cover and disturbance. Science of The Total Environment, 672, 643–656. https://doi.org/10.1016/j.scitotenv.2019.03.494

Fenech, A., Chen, A., Clark, A., & Hedley, N. (2017). Building an Adaptation Tool for Visualizing the Coastal Impacts of Climate Change on Prince Edward Island, Canada. In W. Leal Filho & J. M. Keenan (Eds.), Climate Change Adaptation in North America: Fostering Resilience and the Regional Capacity to Adapt (pp. 225–238). Springer International Publishing. https://doi.org/10.1007/978-3-319-53742-9_14

Groynes, breakwaters and artificial reefs. (n.d.). Climate-Adapt. https://climate-adapt.eea.europa.eu/en/metadata/adaptation-options/groynes-breakwaters-and-artificial-reefs

Keim, B. D., Muller, R. A., & Stone, G. W. (2004). Spatial and temporal variability of coastal storms in the North Atlantic Basin. Marine Geology, 210(1), 7–15. https://doi.org/10.1016/j.margeo.2003.12.006

Logan, C. (2022, September 29). Hurricane Fiona washed away P.E.I. coastline in hours. Canada’s National Observer. https://www.nationalobserver.com/2022/09/29/news/hurricane-fiona-washed-away-pei-coastline-hours

Revetment. (n.d.). In The Merriam-Webster.com Dictionary. https://www.merriam-webster.com/dictionary/revetment

Silliman, B. R., He, Q., Angelini, C., Smith, C. S., Kirwan, M. L., Daleo, P., Renzi, J. J., Butler, J., Osborne, T. Z., Nifong, J. C., & van de Koppel, J. (2019). Field Experiments and Meta-analysis Reveal Wetland Vegetation as a Crucial Element in the Coastal Protection Paradigm. Current Biology, 29(11), 1800-1806.e3. https://doi.org/10.1016/j.cub.2019.05.017

Thompson, K. R., Bernier, N. B., & Chan, P. (2009). Extreme sea levels, coastal flooding and climate change with a focus on Atlantic Canada. Natural Hazards, 51(1), 139–150. https://doi.org/10.1007/s11069-009-9380-5

Yarr, K. (2022, September 27). P.E.I. National Park dunes suffer “extremely dramatic” erosion from Fiona. CBC News. https://www.cbc.ca/news/canada/prince-edward-island/pei-fiona-national-park-dune-damage-1.6597053