With the longest coastline in the world, Canada is at high risk for flooding, storm surge and erosion as climate change progresses. To protect coastal areas and communities, the NRC's Ocean, Coastal and River Engineering Research Centre is exploring nature-based solutions beyond traditional seawalls and breakwaters to enhance coastal resilience.

In 2019, CB Wetlands & Environmental Specialists (CBWES), a Canadian company in Atlantic Canada with expertise in coastal wetland restoration, was commissioned by Fisheries and Oceans Canada's Small Craft Harbors program to design and monitor a conservation offsetting project for piping plover habitat on the Chiasson Office spit, near Shippagan, New Brunswick. The piping plover is a small shorebird that nests and feeds along coastal sand and gravel beaches. This project arose from the Shippagan Gully dredging and breakwater construction project, which modified significant portions of the spit to address navigation hazards. CBWES proposed restoring the lost habitat using nature-based techniques and piloted Canada's first sand engine involving the reuse of the dredged material.

The NRC, in partnership with Saint Mary's University, is currently using numerical modelling tools to determine the effectiveness of this approach. The goal is to validate, demonstrate and enhance predictive tools for assessing the performance of the sand engine that will allow it to better withstand storms and reduce erosion rates in a Canadian coastal setting.

Ocean waves and currents transport sand, shifting it from one location to another. One approach for protecting the eroding sandy beaches is to resupply them with new sand. But this method often needs maintenance year after year because the ocean continuously transports the sand away. Rather than relying on conventional methods that work against ocean waves and currents, researchers can study and create computer models of sand movement in coastal areas to predict where sand needs to be placed for the ocean to naturally move it onto the beach rather than away from it. The mechanism of depositing a large volume of sand in strategic locations along the coast to be distributed gradually and naturally on nearby beaches is called a sand engine.

Behnaz Ghodoosipour, a research associate at the NRC's Ocean, Coastal and River Engineering Research Centre, has designed a detailed numerical model to predict sediment transport around the Chiasson spit. The dredged sand from shipping channels (which is typically dumped offshore) has already been used in the past to create a sand engine to help to nourish the eroding beach. The purpose of this modelling task was to predict future behaviour of sediment transport in the area, making it possible to study both the positive and negative impacts of the sand engine on beach erosion and piping plover habitat. To enhance the accuracy of this model, Jubin Thomas, a postdoctoral researcher at Saint Mary's University, provided essential field measurements of waves and currents, which were integral to validating the model.

The sand engine was put in place in 2021. The observations so far have been positive: sand is continuing to accumulate on the beach, widening it. There have also been reports of piping plovers returning to the beach where their habitat has been re-established. The numerical model results will be used to improve the sand engine by predicting future changes and determining the optimal locations for dumping dredged material, thereby improving overall outcomes.

Photo credit: Courtesy of CBWES

The NRC is well equipped to undertake such research with its expertise and resources. "With deep knowledge in the realm of coastal engineering science, our experts ensure that our computational resources are fully leveraged to tackle complex numerical modeling tasks for solving complex coastal challenges," Ghodoosipour says. "In addition, our high-performance server allows us to efficiently process complex simulations and significantly reduce runtime." This advanced infrastructure makes it possible for researchers to complete runs of sophisticated models in a fraction of the time it would take on less capable systems, ensuring timely and accurate results. And, as she says, "Our access to specialized computing resources enhances our ability to handle large-scale analyses and deliver high-quality outcomes."

Ghodoosipour considers nature-based sustainable solutions for coastal protection to be essential in the long term, especially given that Canadian coasts are often exposed to extreme events such as storms, hurricanes and heavy rainfall, all of which increase coastal erosion and flooding. "Nature-based solutions, and in this case the sand engine, a method that involves beneficial reuse of dredged material in ways previously thought ineffective, offer a sustainable approach to both safeguarding our coastlines against erosion and preserving our ecosystem."

From: National Research Council Canada