Information about seabed stability and sediment dynamics is part of the fundamental geoscience knowledge required for the extraction of tidal energy in the Bay of Fundy and for the integrated management of the Bay. Waves, tidal currents, and wind-driven and circulation currents were obtained from oceanographic models to assess the wave and current processes for the broader Bay of Fundy. The wave and current outputs were coupled with observed grain size in a sediment transport model to predict, for the first time, the seabed shear stresses, sediment mobility, and sediment transport patterns for the entire Bay. The root mean square tidal current, highest in the upper Bay (>1.4 m·s−1), is reduced to moderate in the central Bay (0.5–0.8 m·s−1) and decreases further in the outer Bay (0.2–0.5 m·s−1). The maximum tidal current occurs in the Minas Passage and is >5 m·s−1. The mean significant wave height, in contrast, is the greatest in the outer Bay (∼1.3 m) and gradually decreases to the northeast in the central and upper Bay (<0.5 m). Seabed shear in the Bay of Fundy is mostly due to tides, and wave effects are only important in coastal areas. The strongest mean shear velocity of 10 cm·s−1 occurs in the Minas Passage area. Strong shear velocity of 4–5 cm·s−1 also occurs in Minas Basin, in the central Bay, and in the narrows around Grand Manan Island. Sediment mobilization in the Bay of Fundy is predominantly by tidal current. Mobilization frequency is >30% of the time over most of the Bay and reaches 100% of the time in some areas. The maximum total-load sediment transport rate under spring tide can reach ∼5 kg·m−1·s−1 and is to the northeast during flood and to the southwest during ebb. Net sediment transport flux, however, is dominantly to the northeast and reaches 2 kg·m−1·s−1. Eddies of net transport are found to occur around headlands and at the narrows of Grand Manan Island, largely due to the occurrence of eddies of residual tidal flows. The regional distribution of substrate types and bedform fields and patterns of seabed erosion and deposition are well correlated with tidal current strength and sediment transport patterns.
Modelling Seabed Shear Stress, Sediment Mobility, and Sediment Transport in the Bay of Fundy
Title: Modelling Seabed Shear Stress, Sediment Mobility, and Sediment Transport in the Bay of Fundy
September 01, 2015
Journal: Canadian Journal of Earth Sciences
Publisher: NRC Research Press
Li, M.; Hannah, C.; Perrie, W.; Tang, C.; Prescott, R.; Greenberg, D. (2015). Modelling Seabed Shear Stress, Sediment Mobility, and Sediment Transport in the Bay of Fundy. Canadian Journal of Earth Sciences, 52(9), 757-775.