Suspended Sediment Transport and Deposition Modeling in the Bay of Fundy, Nova Scotia — a Region of Potential Tidal Power Development

Abstract

Two recent independent studies of the Minas Basin have been combined to produce a numerical simulation of suspended sediments. One study devised a numerical, barotropic tidal model of the Bay of Fundy and Gulf of Maine, which produced a good simulation of the tides and currents in the Minas Basin. The second, an extensive program of sediment sampling and monitoring addressed the nature of suspended sediments, bottom sediments, their various sediment sources and the postglacial evolution of the system. The only significant source of suspended sediment was from the open boundary to the Minas Basin and was of relatively uniform concentration through the water column. Consequently, the barotropic tidal model was well suited to modeling this material. Sediment laws describing sediment settling, resuspension, and the critical stress for entrainment were obtained from the literature and evaluated. The settling velocity of the suspended sediment was obtained by experimentation using actual water/sediment samples. Because the various parameters and critical stresses show a considerable variation among experimenters, runs were planned to examine a range of parameters. A close fit to existing conditions was obtained with the model generating mudflats in those regions where indeed they exist. Using the various parameters and critical stresses reflecting maximum sedimentation, the model was run to include the effects of a tidal power barrage off Economy Point. It is concluded that suspended sediment would not inhibit the operation of such a barrage through siltation directly in front of or behind the barrier. Increased siltation can be expected in the intertidal areas behind the barrage. Sediment budget considerations further limit the degree of post barrier siltation, insofar as the resident volume of suspended material (30 × 106 m3) is not enough to significantly reduce the headpond area.Key words: suspended sediment, sediment transport, numerical model, tide