The introduction of in-stream turbines in Minas Channel could impose changes to the oceanographic conditions on the tidal flats, at the shoreline, and in river channels in Minas Basin that might result in sediment erosion/accretion as the system adjusts to a new equilibrium. The goal of this research project is the development of numerical hydrodynamic and sediment transport models for Minas Basin in the Bay of Fundy, the focus of which will be the sediment dynamics of the tidal inlets and flats. The models have been validated by field observations and used for prediction of the impacts of tidal power devices on the dynamics of coastal flows, sediment transport and seabed morphology. These models include the relevant physical processes for sediment dynamics, including tidal currents, river flows and wave-induced sediment mobilization and re-suspension. The models used for this study are the first step in addressing the problem of sedimentation in tidal rivers and on the tidal flats induced by tidal energy extraction.
The models are based on existing and well established in three-dimensional models for hydrodynamics (Delft3D and FVCOM), and use coupled nested grids or unstructured meshes to appropriately resolve the locations of interest within Minas Basin. Model grids have been developed using existing high-resolution multi-beam bathymetry (Parrott et al, 2008). Relevant forcing mechanisms are evaluated and included, for example tides, storm surges, winds and waves. The model results have been used to evaluate sediment erosion, suspension, transport and deposition. The domain encompasses all of Minas Basin, with the boundary placed in Minas Passage such that changes in boundary conditions may be used to represent various tidal energy extraction schemes. The impacts of single turbines, lines and arrays of turbines are simulated in the model flows as well. Regarding validation of the natural system, the models are used to predict sediment changes during the spring/neap tidal cycle and compared with data reported by Amos and Joice (1977) and concurrent observations by others, including measurements of sediment concentration profiles, erosion and deposition rates in sensitive estuaries of the Avon and Cornwallis Rivers and nearby tidal flats in the upper Bay of Fundy. The predicted differences between spring and neap conditions are used as a proxy for before and after tidal energy extraction. The modelling system was used to predict changes to tidal currents, water levels, sediment concentrations, sediment transport rates and areas of seabed erosion/accretion. This research identifies some of the impacts of tidal power generation on the coastal marine environment in Minas Basin, which benefits and complements other environmental research.