Nearshore strategic shallow water placement—in addition to direct placement—has been proposed as a method to reuse dredged sediment in support of mitigating the effects of sea level rise in the San Francisco Bay Area. The success of nearshore strategic shallow water placement relies on hydrodynamic forces moving sediment from the placement site to mudflats and marshes over time. Sediment transport and pathway models can be used to evaluate and prioritize potential placement sites, placement methods, transport rates (informing amount and frequency of sediment placement), sediment fate, and longevity. Models can also be used to predict the evolution of sites after initial placement and as sea level and sediment supply conditions evolve. This model-based information is needed to design wetland restoration and maintenance operations, inform the permitting approval process, and evaluate the costs and benefits of using strategic placement techniques to restore and maintain Bayland habitats in San Francisco Bay. This work focuses on the estuarine process modeling as well as in-situ observation efforts that are being undertaken to assess sediment fate, sediment transport rates and sediment transport dynamics associated with nearshore strategic placement.

This experimental modelling study aims to provide knowledge about the hydraulic performance of environmentally-friendly armour units tested on permeable low-crested and conventional rubble mound breakwaters under diverse wave conditions. Collaboration between the University of Ottawa, the National Research Council of Canada (NRC), and ECOncrete Tech. Ltd. facilitated the development and implementation of the physical modelling program. This initiative is crucial for encouraging the use of ecologically enhanced armour units in the design of new coastal structures (such as Baker et al., 2018) and for ecologically retrofitting existing coastal structures. The physical tests, conducted from June 2023 to August 2023 at NRC's Ocean, Coastal, and River Engineering Research Center in Ottawa, Canada, involved assessing ECOncrete's Coastalock armor units in various configurations at a 1/15 scale. Two-dimensional models of low-crested and conventional RMBWs were subjected to severe wave conditions with significant wave heights ranging from 1.2m to 5.7m (prototype scale), and wave steepness ranging between s=0.025 and s=0.07 to evaluate the hydraulic performance and failure mechanisms of the tested armour units. Furthermore, the hydraulic behaviour of low-crested and conventional RMBW models was analyzed by comparing the experimental results of wave reflection, wave transmission, and overtopping with formulas from the literature.

Located in North-Eastern Canada near Shippagan, New Brunswick, the Shippagan project is leveraging salt marsh creation and sand engine techniques to increase resiliency for the Chaisson Office spit and surrounding communities. The barrier spit has been altered and degraded by more than a century of human activity and is being increasingly impacted by climate change and sea-level rise. The project, which utilizes a holistic approach to improve marine navigation into the gully and install nature-based solutions (NbS) for coastal protection and habitat creation, is the first sand engine in Atlantic Canada and the most northern created marsh with sill to date. Extensive modeling was undertaken by NRC prior to the commencement of baseline data collection and NbS design in 2017. Several monitoring and research initiatives are associated with project, including a fifteen-year monitoring program (regulatory requirement), five-year post-graduate scientific research program, and a 3-year research project which will augment and build on the NRC-led Nature-Based Infrastructure for Coastal Resilience project. Construction began on the sand engine in 2020, with the marsh and marsh sill built in winter 2023 and planted in spring 2023. The final stages of the implementation will include dune and wetland restoration, returning nearly the entire spit to a more natural state. The first two years of monitoring have showed a shift in conditions to those more closely matching a nearby control site, as well as successful nesting and fledging of Piping Plover (Federally Endangered Species) on the site. The project is the result of a collaborative effort that includes federal and provincial government departments, private industry, academia, and environmental NGOs.

Globally, the practice of re-introducing, where feasible, tidal flow to former agricultural dykelands and the restoration of tidal wetland habitat, has been identified as a viable adaptation method to current and future hazards associated with climate change. While previous efforts to restore coastal wetlands in Atlantic Canada focused primarily on the restoration of resilient and self-sufficient habitats, the increasingly tangible impacts of climate change combined with changing economic landscapes, regulations, and land use practices have shifted and broadened the objectives of these projects. With limited resources available, guidance is required to determine where and how dykes should be re-aligned to optimize ecosystem services, maximize adaptation benefits, minimize economic costs, and maintain fertile agricultural land and social, cultural, and historic activities. The Making Room for Wetlands project is building resilience to climate change impacts of dykelands in the Bay of Fundy, Canada by demonstrating the successful of implementation of managed dyke realignment and the restoration of salt marsh habitat. Demonstration sites were selected in collaboration with the Provincial body responsible for dyke maintenance, after a comprehensive dyke vulnerability assessment and builds upon over two decades of collaboration and experience in tidal wetland restoration. The managed realignment process is a complex process, with multiple stages that rely upon each other and may be revisited several times. Focus will be on the influence of sediment supply, tidal range, restoration design and seasonal timing of re-introduction of tidal flow on the rate of vegetation recolonization and implications for long term resilience.

The Qiantang River is a typical strong tides estuary, the average tidal range at Ganpu Station of estuary headbay is 5.66m, the maximum tidal range is 9.01m. The tidal wave propagates to the up-river section from Ganpu, shallow water deformation effect intensifies, gradually forming the world-famous tidal bore, galloping more than 100 kilometers up. The tidal bore is a special phenomenon of water movement, high flow velocitystrong turbulence, and complex flow characteristics, the huge energy causes damage to the sea wall. When the tidal bore arrives, the water flow rapidly changes from the ebb to the flood, and flow velocity quickly reaches the extreme value. The rapid change of water flow characteristics brings strong turbulence effect, the tide head swirling and break, dissipate huge turbulent energy, sharply scour riverbed, causing great damage to the foundation of buildings such as seawall, this is one of the main factors causing damage to seawall at the Qiantang River Estuary (Fig 1).Spur dike is an important engineering to protect the seawall foundation from tidal bore scour,, there are more than 320 spur dikes in estuary now, but with the evolution of the river regime, still many sections of the seawall foundation scour issue is grim, necessary to build more spur dikes for protection. The hydraulic characteristics of the tidal bore are different from ordinary water flow, so parameters of the spur dikes are special. The tidal bore occurs at the low water level, at this time the river water depth shallow and beach dry, the tidal bore head directly acts on the beach with strong turbulence, the beach sediment was heavily lifted, the sand content of the tidal bore head water could reach 45kg/m3. After the bore head, the water level rises sharply 2-3m, the high velocity flow (fast water) could reach 6-10m/s, which has massive sediment scour and transport capability. So the beach in front of seawall be serious scoured, endangering the safety of seawall foundation. After spur dike is constructed, the tidal bore and flow moved away from the seawall foundation, hydrodynamic forces in front of the seawall be weakened, forming backflow, sediment deposition, and the beach surface elevate, the foundation of the seawall be protected. The matching of spur dikes parameters with hydrodynamic forces determine the protection effect, the severity of the scouring pits around dike-head by bypass flow and at uprearch dike-body by overing dike bore is closely related to the parameters of the spur dikes. So the spur dikes parameters such as high, length, inclination angle and intal space need to be determined by physical model according to the specific bore dynamic conditions.

A study has prequalified Contrecoeur sediments as pozzolans. A new study aims to design concrete for the Port of Montreal incorporating 10-20% sediment for a low-carbon footprint project. The research extends to the manufacture of 3D printable mortar with dredged sediments, exploring sustainability. This innovative project contributes to the knowledge of dredged sediments, promoting sustainable construction practices and highlighting their value.