Sand Dunes Protect Coastlines From Climate Change but May Get Vulnerable to Intense Storms, Study Suggests

After an intense storm struck a Canadian province, scientists realized what damage and recovery might mean for sand dunes.

Nature of Sand Dunes

Sand dunes refer to naturally occurring accumulations of sand in ridges or mounds landward of the beach. They are created when waves deposit sand on a beach, and winds shape it into mounds. During storms, rows of dunes serve as barriers that protect everything inland. As described by ecologist Hailey Paynter from Parks Canada, sand dunes are built to withstand storms. They only need time and space to regrow.

The speed of dune recovery depends on the amount of sand available to feed them, requiring relatively wide beaches and dry sand. Sand dunes on narrower beaches or those often submerged by the tide usually take longer to rebuild.

Crucial Barrier at Risk

On September 24, 2022, Hurricane Fiona landed on Prince Edward Island in Atlantic Canada. This storm, considered one of the strongest cyclones ever recorded in Canada, left Greenwich Beach closed to the general public for several weeks.

Coastal geomorphologist Jeff Ollerhead from Mount Allison University in New Brunswick had been monitoring the Greenwich Dunes for 20 years until 2015. After observing the upended boardwalk in Prince Edward Island National Park, he noted how the waves had damaged large amounts of sand from the seaward side and left the dune's normally sloping face almost vertical.

The damage observed by Ollerhead was not unexpected, knowing that the sand dunes have faced similar damage. One hundred years ago, Greenwich was utterly wiped out by storms and regenerated only over the following decades. What makes the situation alarming is that the sand dunes now have less time to recover. Scientists try to determine the effect of climate change as it fuels more frequent and powerful storms.

Greenwich Beach is a seven-kilometer stretch of dunes containing vegetation on top, which holds the sand in place. Even the high waves of Hurricane Fiona failed to damage its crest. While the waves eroded the dunes, the sand prevented the storm surge from flooding.

A year after the onslaught of Hurricane Fiona, the Greenwich Dunes have shown signs of recovery, with plants starting to pop up in the ridges closest to the ocean. The sand dunes will gradually grow in the coming year as blowing sand gathers around the vegetation.

Dune recovery is not an issue on Greenwich Beach because sand is abundant in this area. However, environmental challenges can be experienced in other areas. Winds naturally change the position of dunes, and major storms can slowly move dunes inland by pushing sand from the ocean-facing side over the top. When bigger and more frequent hurricanes strike an area, repeated erosion could transport so much sand that dunes may reform elsewhere.

Humans can take action to make sure that the sand is kept in place and that dunes protect important areas. In some places, people shore up vulnerable sand dunes by trucking in beach sand and reinforcing the mounds with materials that slow down sand movement.

According to Ollerhead, the natural recovery of sand dunes may be slow, but nature can do it better than humans. Therefore, humans can do their part by leaving dunes alone to be as resilient as possible before a storm hits.

In the case of Greenwich Dunes, there is plenty of space to shift and regrow with storms since the surrounding area is protected from development by the national park. While it is impossible to predict how long Greenwich Dunes will take to reach their former size, experts are confident that the forecast for dunes is generally good even during severe hurricanes as long as humans take good care of them.