Oyster reef ecosystems are essential for marine life and have been known for being self-sustaining and keeping pace with sea level rise. Reefs provide nutrient regulation and also mitigate erosion by reducing the impact of waves. This wave mitigation benefits surrounding habitats like salt marshes. Because of these beneficial properties there has been a rise in reef restoration, but little is known about how sand and other sediments settle around rebuilt oyster reefs. The U.S. Army Corps of Engineers (USACE) awarded Alberto Canestrelli, Ph.D., an assistant professor in the Department of Civil and Coastal Engineering, a $1 million grant to explore and quantify restored oyster reef ecosystems’ sediment retention and impact on shoreline erosion.
To conceptualize what is happening with these ecosystems, Dr. Canestrelli will use a combination of physical experiments and high-resolution 3D numerical simulations to estimate how different geometries of reefs and shore affect the volume of sediments trapped between the reef and the shore. These sets of experiments will be used to improve parameterizations for sediment transport models that estimate the rates of longshore progradation and deposition and identify whether the shoreline is expanding or retreating in proximity to a restored reef.
“It is unclear which is the optimal geometry of a restored reef to maximize sediment retention and shore progradation. This funding enables us to explore the full space of parameters affecting deposition behind oyster reefs, such as reef geometry, distance from the coast, size of gaps between reefs, as well as characteristics of wave and tidal forcings,” Dr. Canestrelli said. “Our dataset will offer detailed insight into how sediment concentration and velocity profiles around oyster reefs depend on different geometrical and hydrodynamic parameters. This will help quantify sediment trapping behind the reef and optimize the benefits of the restored reef to the ecosystem.”
The results of this research will provide insight and guidelines for the design of tailored reef restoration projects. “Understanding sediment transport around oyster reefs is challenging due to the complex flow patterns they create. This knowledge gap is significant because it hinders our ability to design effective reef-based shoreline protection strategies,” Dr. Canestrelli said. “For a reef to be effective, it needs to maximize sediment deposition between them and the shore. Employing an optimal reef geometry can lead to more effective and sustainable restoration strategies, which ensures that oyster reefs provide both shoreline progradation and ecosystem benefits.”
This project aligns with the USACE’s goals of enhancing coastal resilience and ecosystem restoration. Ultimately, Dr. Canestrelli’s goal is to offer optimized nature-based solutions that employ restored oyster reefs for shoreline protection.
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