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Comparison of Two and Three-Dimensional Model Simulation of the Effect of a Tidal Barrier on the Gulf of Maine Tides
Abstract
Two-dimensional and three-dimensional tide models were used to simulate the M2 tide in the Gulf of Maine. Model estimates of changes to the tide caused by a tidal barrier in the upper Bay of Fundy were made and compared. Tidal amplitudes in the presence of a barrier increased 30-50 cm for both models. The three-dimensional model uniformly produced postbarrier elevations of 3.5 cm less than the two-dimensional model. Root-mean-square errors of M2 tidal amplitude and phase at 45 locations in the Gulf of Maine were 7.9 cm and 6° for the two-dimensional model and 5.7 cm and 7° for the three-dimensional model. -from Authors
... Because of the near-resonant state of the existing system, it has been shown that small changes in the geometry of the Bay associated with the construction of a tidal barrage could produce significant changes in tidal amplitudes as far away as Boston. Sucsy et al. [5] used two and three-dimensional models to simulate the M 2 tide in the Gulf of Maine and estimate the changes caused by a large tidal barrier located in the upper Bay of Fundy. Tidal amplitudes in the presence of a barrier increased by up to 50 cm for both models, corroborating Greenberg's earlier results. ...
... Previous studies [4,5] have suggested that large tidal barrages located in the upper BoF could have important impacts on the tides and tide-related processes in the BoF and GoM. However, recent studies from the UK [8,9] suggest a large tidal power lagoon located in the Severn Estuary would have lesser impact on the hydrodynamic processes in the Estuary. ...
... Many previous researchers considered only the M 2 tidal constituent when studying the hydrodynamic impacts due to tidal power projects in the Bay of Fundy [4,5]. The M 2 constituent is certainly dominant and contributes over 80% of the total tidal energy in the upper Bay [16]. ...
The Bay of Fundy is home to some of the world's largest tides and has long been identified as one of the world's premier locations for the installation of tidal power generating systems. This paper deals with the assessment of hydrodynamic impacts throughout the Bay of Fundy and Gulf of Maine due to power generation by tidal lagoons located in Minas Basin. The lagoon concept involves temporarily storing seawater behind an impoundment dike and generating power by gradually releasing the seawater through conventional low-head hydroelectric turbines. Tidal lagoons represent a relatively novel approach to tidal power generation, and are intended to achieve high efficiency while avoiding some of the environmental problems associated with tidal barrages. A detailed two-dimensional (depth-averaged) finite-element numerical model, based on the TELEMAC system, has been developed, calibrated against observed water levels and velocities, and applied to simulate tidal hydrodynamics throughout the Bay of Fundy and Gulf of Maine, both for existing conditions without a lagoon and for two scenarios with tidal lagoons operating in Minas Basin. A 12 km 2 offshore lagoon with 14 turbines generating ∼124 MW on average and a 24 km 2 coastal lagoon with 24 turbines generating ∼220 MW on average have been investigated. This paper provides a summary of the work that has been performed to date and presents results describing the local and far-field changes in water levels and tidal currents due to tidal lagoons operating in the upper Bay of Fundy.
... Greenberg [9] calculates both potential and kinetic energies on the order of 10 14 J. Until recently, the methods of harvesting this tidal energy were limited to capturing water in a dam at high tide and generating electricity by releasing the water at low tide. Previous studies [9,12] have investigated the possibility of building such a dam near the Minas Passage. Both studies used numerical simulations to conclude that the tides would increase significantly along the coast of Maine and Massachusetts, as a result of pushing the system closer to resonance. ...
... After conducting several numerical simulations, this bottom friction coefficient was determined to be 0.0026. In comparison, Dupont et al. [4] achieved their smallest error using a coefficient of 0.0025; whereas, Sucsy et al. [12] used 0.002. Greenberg [9], on the other hand, used two different values -0.0024 in the Gulf of Maine, and 0.0021 for the remainder of the region. ...
... Observations were not obtained for Cape Split; however, it is included in the table because the phase and amplitude at the entrance to the Minas Passage is important in the discussion of turbines in Section 4. For all 51 stations, the root mean square (rms) amplitude difference is 8 cm and the rms phase difference is 3.1 • . In general, our errors are slightly smaller than those of Greenberg [9] and comparable to Sucsy et al. [12] and Dupont et al. [4]. ...
... Because of the near-resonant state of the existing system, it has been shown that small changes in the geometry of the Bay associated with the construction of a tidal barrage could produce significant changes in tidal amplitudes as far away as Boston. Sucsy et al. [5] used two and three-dimensional models to simulate the M 2 tide in the Gulf of Maine and estimate the changes caused by a large tidal barrier located in the upper Bay of Fundy. Tidal amplitudes in the presence of a barrier increased by up to 50 cm for both models, corroborating Greenberg's earlier results. ...
... Previous studies [4,5] have suggested that large tidal barrages located in the upper BoF could have important impacts on the tides and tide-related processes in the BoF and GoM. However, recent studies from the UK [8,9] suggest a large tidal power lagoon located in the Severn Estuary would have lesser impact on the hydrodynamic processes in the Estuary. ...
... Many previous researchers considered only the M 2 tidal constituent when studying the hydrodynamic impacts due to tidal power projects in the Bay of Fundy [4,5]. The M 2 constituent is certainly dominant and contributes over 80% of the total tidal energy in the upper Bay [16]. ...
The Bay of Fundy located in eastern Canada is home to some of the world’s largest tides. Currently there is renewed interest in harnessing these very large tides for power generation in ways that avoid upsetting ecosystems, infrastructure and human activities that are presently well adapted to existing conditions. This paper investigates the hydrodynamic impacts due to tidal power lagoons, an approach to power generation that involves temporarily storing seawater behind a circular engineered dyke and generating power by gradually releasing the impounded seawater through conventional low-head hydroelectric turbines. This paper describes a study in which a two-dimensional, depth-averaged hydrodynamic model based on the TELEMAC modelling system was developed, calibrated, and applied to analyze, predict, and quantify the potential changes in tidal hydrodynamics (water levels, tide range, circulation patterns and tidal currents) throughout the Bay of Fundy and Gulf of Maine due to the presence of a single tidal lagoon and multiple lagoons operating at various locations in the upper Bay of Fundy. The sensitivity of the hydrodynamic impacts to changes in lagoon type, size, location, the number of lagoons, and their operating mode have also been investigated. The methods employed in this study and the main findings are presented and discussed herein. These results will help inform future decisions concerning development of the vast tidal energy resources in the Bay of Fundy.
... Because of the near-resonant state of the existing system, it has been shown that small changes in the geometry of the Bay associated with the construction of a tidal barrage could produce significant changes in tidal amplitudes as far away as Boston. Sucsy et al. [5] used two and three-dimensional models to simulate the M 2 tide in the Gulf of Maine and estimate the changes caused by a large tidal barrier located in the upper Bay of Fundy. Tidal amplitudes in the presence of a barrier increased by up to 50 cm for both models, corroborating Greenberg's earlier results. ...
... Previous studies [4,5] have suggested that large tidal barrages located in the upper BoF could have important impacts on the tides and tide-related processes in the BoF and GoM. However, recent studies from the UK [8,9] suggest a large tidal power lagoon located in the Severn Estuary would have lesser impact on the hydrodynamic processes in the Estuary. ...
... Many previous researchers considered only the M 2 tidal constituent when studying the hydrodynamic impacts due to tidal power projects in the Bay of Fundy [4,5]. The M 2 constituent is certainly dominant and contributes over 80% of the total tidal energy in the upper Bay [16]. ...
The Bay of Fundy located in eastern Canada is home to some of the
world’s largest tides. Currently there is renewed interest in harnessing
these very large tides for power generation in ways that avoid
upsetting ecosystems, infrastructure and human activities that
are presently well adapted to existing conditions. This paper investigates
the hydrodynamic impacts due to tidal power lagoons, an
approach to power generation that involves temporarily storing
seawater behind a circular engineered dyke and generating power
by gradually releasing the impounded seawater through conventional
low-head hydroelectric turbines. This paper describes a study
in which a two-dimensional, depth-averaged hydrodynamic model
based on the TELEMAC modelling system was developed, calibrated,
and applied to analyze, predict, and quantify the potential
changes in tidal hydrodynamics (water levels, tide range, circulation
patterns and tidal currents) throughout the Bay of Fundy and
Gulf of Maine due to the presence of a single tidal lagoon and multiple
lagoons operating at various locations in the upper Bay of Fundy.
The sensitivity of the hydrodynamic impacts to changes in
lagoon type, size, location, the number of lagoons, and their operating
mode have also been investigated. The methods employed in
this study and the main findings are presented and discussed
herein. These results will help inform future decisions concerning
development of the vast tidal energy resources in the Bay of Fundy.
... Although such constructions will obviously have a large impact on the local environment [4], previous research suggests that adding a barrier near the Minas Passage would also cause large changes throughout the entire Bay of Fundy-Gulf of Maine system as the system is pushed closer to resonance. As such, adding a barrier increases the amplitude of tides by 20 to 30 per cent along the coast of Maine and Massachusetts [2,5]. ...
... These values of c and λ can be compared with the values given by equation (5) and the formula for the bottom-friction drag given by [13] Table 1. The values for a b and a are taken to be the averaged undisturbed tidal amplitude in the Minas Basin and along the western entrance to the Minas Passage, respectively. ...
... The resulting tidal amplitude and phase were then compared with observations. On average, the accuracy was within 8 cm in amplitude and 3.1 • in phase, comparable with other studies [2,5,14]. Other aspects of the model tides, such as energy, dissipation rates, etc., were also compared with these studies to ensure that all aspects of the model were realistic. ...
Theories of in-stream turbines are adapted to analyse the potential electricity generation and impact of turbine arrays deployed in Minas Passage, Bay of Fundy. Linear momentum actuator disc theory (LMADT) is combined with a theory that calculates the flux through the passage to determine both the turbine power and the impact of rows of turbine fences. For realistically small blockage ratios, the theory predicts that extracting 2000-2500 MW of turbine power will result in a reduction in the flow of less than 5 per cent. The theory also suggests that there is little reason to tune the turbines if the blockage ratio remains small. A turbine array model is derived that extends LMADT by using the velocity field from a numerical simulation of the flow through Minas Passage and modelling the turbine wakes. The model calculates the resulting speed of the flow through and around a turbine array, allowing for the sequential positioning of turbines in regions of strongest flow. The model estimates that over 2000 MW of power is possible with only a 2.5 per cent reduction in the flow. If turbines are restricted to depths less than 50 m, the potential power generation is reduced substantially, down to 300 MW. For large turbine arrays, the blockage ratios remain small and the turbines can produce maximum power with a drag coefficient equal to the Betz-limit value.
... Greenberg [9] calculates both potential and kinetic energies on the order of 10 14 J. Until recently, the methods of harvesting this tidal energy were limited to capturing water in a dam at high tide and generating electricity by releasing the water at low tide. Previous studies [9, 12] have investigated the possibility of building such a dam near the Minas Passage. Both studies used numerical simulations to conclude that the tides would increase significantly along the coast of Maine and Massachusetts, as a result of pushing the system closer to resonance. ...
... After conducting several numerical simulations, this bottom friction coefficient was determined to be 0.0026. In comparison, Dupont et al. [4] achieved their smallest error using a coefficient of 0.0025; whereas, Sucsy et al. [12] used 0.002. Greenberg [9], on the other hand, used two different values – 0.0024 in the Gulf of Maine, and 0.0021 for the remainder of the region. ...
... The final results for nine observation stations are summarized inTable 1. Observations were not obtained for Cape Split; however, it is included in the table because the phase and amplitude at the entrance to the Minas Passage is important in the discussion of turbines in Section 4. For all 51 stations, the root mean square (rms) amplitude difference is 8 cm and the rms phase difference is 3.1 @BULLET . In general, our errors are slightly smaller than those of Greenberg [9] and comparable to Sucsy et al. [12] and Dupont et al. [4]. The calculated tidal amplitudes and phases are displayed for the Minas Passage and Minas Basin inFigure 3. It is evident in this figure that the amplitude of the simulated tide is greater than 6 m in some regions of the Minas Basin. ...
Large tidal currents exist in the Minas Passage, which connects the Minas Basin to the Bay of Fundy off the north-western coast of Nova Scotia. The strong currents through this deep, narrow channel make it a promising location for the generation of electrical power using in-stream turbines. Using a finite-volume numerical model, the high tidal amplitudes throughout the Bay of Fundy are simulated within a root mean square difference of 8 cm in amplitude and 3.1 • in phase. The bottom friction in the Minas Passage is then increased to simulate the presence of turbines and an estimate of the extractable power is made. The simulations suggest that up to 6.9 GW of power can be extracted; however, as a result, the system is pushed closer to resonance which causes an increase in tidal amplitude of over 15% along the coast of Maine and Massachusetts. The tides in the Minas Basin will also experience a decrease of 30% in amplitude if the maximum power is extracted. Such large changes can have harmful environmental impacts; however, the simulations also indicate that up to 2.5 GW of power can be extracted with less than a 6% change in the tides throughout the region. According to Nova Scotia Energy, 2.5 GW can power over 800,000 homes.
... Removal of hydraulic structures alters marine hydrodynamics, including tidal dynamics (McAlice and Jaeger 1983;Sucsy et al. 1993) and sediment discharge (Haralampides and Rodriguez 2006;Morand and Haralampides 2006). Augmented sediment discharge may increase fine-grained sediment deposition on beaches or tidal flats (Bednarek 2001). ...
... Studies like the one presented here will be necessary in other areas, as our findings may not be applicable to all marine systems, especially those not dominated by macrotides. River blockage removal has been observed to have both short-and long-term impacts on marine hydrodynamics in other systems (McAlice and Jaeger 1983;Sucsy et al. 1993). Therefore, detailed environmental assessments conducted before, during, and after barrier removal should investigate potential changes Fig. 3 Mean ± standard error (n = 5 rounds, June-September) of community dispersion for the intertidal mudflat invertebrates of the Bay of Fundy, Canada. ...
The spillway gates of the Petitcodiac Causeway, a hydraulic structure ~35 km upstream of the mouth of the Petitcodiac River in New Brunswick, Canada, were permanently opened in April 2010. The short-term effect opening the spillway gates had on downstream intertidal mudflats of the upper Bay of Fundy was investigated. Specifically, a multivariate before-after-control-impact design was used to determine if opening the spillway gates affected the invertebrate community (crustaceans, polychaetes, and molluscs), abiotic sediment conditions (sediment water content, mean particle size, penetrability, and depth of the apparent redox potential discontinuity), or resource availability (sediment chlorophyll a concentration and organic matter content) of five intertidal mudflats (two impacted sites, three reference sites) spanning Chignecto Bay, the northern arm of the upper Bay of Fundy, up to 5 months post-opening. No biologically or statistically meaningful differences were detected between impacted and reference sites for any of the measured variables. This suggests that opening the causeway did not have a quantifiable impact on these intertidal mudflats, at least within half a year of the opening. This is likely a result of the macrotidal nature of the Bay of Fundy that overwhelmed any immediate changes to hydrodynamics that occurred after the opening of the causeway gates.
... The strongest currents in the Bay of Fundy occur in the Minas Passage with flow speeds up to 5 ms −1 . This makes it an ideal location for tidal power extraction by harnessing either potential energy using tidal barrages (Cornett et al., 2013;Greenberg, 1979;Sucsy et al., 1993) or kinetic energy using in-stream turbines (Hasegawa et al., 2011;Mulligan et al., 2013). It is estimated that there is 1.15 × 10 14 J of mean potential energy in the Minas Basin in the upper Bay of Fundy (Greenberg, 1979) and this is equal to over 10 GW of power, about 15% of Canada's annual electrical power consumption (Karsten et al., 2008). ...
... McCombs et al. (2014) simulated turbine monopiles for a wind farm located in Lake Ontario and examined the impacts on waves and lake water circulation. Past numerical studies on tidal power extraction in the Bay of Fundy have assessed the hydrodynamic effects such as changes to water levels (Garrett, 1974;Greenberg and Amos, 1983) and currents (Shaw et al., 2010;Sucsy et al., 1993) and the associated environmental impacts (Cornett et al., 2013;DFO, 2009;Garrett, 1974;Gordon, 1994;OEER, 2008). These studies are based on the implications of tidal barrages (Greenberg and Amos, 1983) and lagoons (Cornett et al., 2013) for tidal power extraction in the Minas Basin. ...
The Bay of Fundy in eastern Canada has the world's largest tidal range of over 16 m with tidal currents up to 5 ms −1 making it an ideal place for tidal power extraction using tidal in-stream energy conversion devices in the Minas Passage. Field observations collected from ship-based and bottom-moored sensors over an 8-day period in 2013 are used to validate a 3D hydrodynamic and sediment transport model of the Minas Basin with measurements of water levels, current profiles, waves, suspended sediment fluxes and suspended sediment concentration (SSC) profiles. The sediment conditions are initialized using a bi-modal sediment distribution map and the model simulates both cohesive and non-cohesive sediments in the Minas Basin. Model results for fine-grained suspended sediment concentrations are compared horizontally, vertically, and temporally to observations and indicate strong data-model agreement for SSC from 5 to 287 mg L −1. The implications of constructing a large-scale turbine farm within the Minas Passage and the impacts on suspended sediment within the Minas Basin are investigated using the model. The farm is simulated by adding semi-permeable structures that use an energy loss term in the fluid momentum equations to parameterize turbine regions in the hydrodynamic model. The results emphasize the sensitivity of the system to changes in flow and suggest that a large-scale tidal energy farm that extracts maximum power could reduce SSC by 37% on average across the basin which would influence physical and biological processes particularly on the fine-grained intertidal areas around the macrotidal basin.
... The strongest currents in the Bay of Fundy occur in the Minas Passage with flow speeds up to 5 ms −1 . This makes it an ideal location for tidal power extraction by harnessing either potential energy using tidal barrages (Cornett et al., 2013;Greenberg, 1979;Sucsy et al., 1993) or kinetic energy using in-stream turbines (Hasegawa et al., 2011;Mulligan et al., 2013). It is estimated that there is 1.15 × 10 14 J of mean potential energy in the Minas Basin in the upper Bay of Fundy (Greenberg, 1979) and this is equal to over 10 GW of power, about 15% of Canada's annual electrical power consumption (Karsten et al., 2008). ...
... McCombs et al. (2014) simulated turbine monopiles for a wind farm located in Lake Ontario and examined the impacts on waves and lake water circulation. Past numerical studies on tidal power extraction in the Bay of Fundy have assessed the hydrodynamic effects such as changes to water levels (Garrett, 1974;Greenberg and Amos, 1983) and currents (Shaw et al., 2010;Sucsy et al., 1993) and the associated environmental impacts (Cornett et al., 2013;DFO, 2009;Garrett, 1974;Gordon, 1994;OEER, 2008). These studies are based on the implications of tidal barrages (Greenberg and Amos, 1983) and lagoons (Cornett et al., 2013) for tidal power extraction in the Minas Basin. ...
... When modifying the form drag in the upper bay, the resonance can be altered so that it becomes difficult to specify boundary conditions in a more limited area model. Moreover, previous studies have shown that introducing features such as barrages can modify the resonance and have significant effects on tides as far as Boston [17]. Hence, it seems appropriate to model the entire system. ...
... Overall, the flood/ebb behavior is consistent with other published results [16,17]. The tidal asymmetry would be expected to cause some problems with the placement of turbines when attempting to extract the maximum power with the minimum number of devices. ...
Several approaches can be used for estimating tidal power potential. From a theoretical point of view,
others have shown that the problem can be reduced to a single or multiple boundary problem with
simple geometry where each case has a well defined maximum power potential. From a practical point of
view, the potential can be approximated from the ambient flow. Questions naturally arise whether the
theoretical approach can be applied to a typical field-scale problem, and whether the practical approach
has any validity. In order to provide more insight into these questions, form drag representing tidal
turbines has been introduced into a numerical flow model. This is an unstructured grid model with an
implicit treatment of wetting and drying that has been shown to be robust, accurate, and efficient for
highly irregular coastal ocean environments and is well suited for this problem. The field site that has
been examined is Minas Passage in the Bay of Fundy which provides an interesting practical perspective
for this problem. In the end, only a fraction of the theoretical maximum power potential can be realized
in practice because of physical constraints on the maximum form drag for tidal turbines.
... A tidal barrage, which is essentially a dam across a river estuary, was constructed in Annapolis Royal near the BoF in 1980, with an installed capacity of about 20 MW. Previous studies have shown that the energy extraction with a barrage in the Upper BoF could significantly increase tidal elevations throughout the Gulf of Maine (GoM) (Greenberg 1979;Sucsy et al. 1993). Furthermore, tidal barrages can have negative environmental impacts on marine life and water quality, similar to those of hydroelectric dams, by decreasing tidal currents and prolonging high tides inside the catch basin ( Sutherland et al. 2007). ...
... To assess the model's performance, the nested-grid model is first used to simulate tidal surface elevations and 3D tidal currents in the BoF-GoM without power extraction in the BoF (i.e., the control run). agree well with previous numerical model results (Greenberg 1979;Sucsy et al. 1993;Karsten et al. 2008). Figure 5b presents the polar plot of observed and simulated amplitudes and phases of M 2 surface elevations at ten tide stations along the coastline in the BoF-GoM region (stations 1 to 10 in Fig. 5a), in which the angular coordinate represents phases and the radial coordinate represents amplitude of M 2 tidal elevation. ...
The Bay of Fundy in eastern Canada has the highest tides in the world. Harnessing the tidal energy in the region has long been considered. In this study, the effects of tidal in-stream energy extraction in the Minas Passage on the three-dimensional (3D) tidal circulation in the Bay of Fundy (BoF) and the Gulf of Maine (GoM) are examined using a nested-grid coastal ocean circulation model based on the Princeton Ocean Model (POM). The nested-grid model consists of a coarse-resolution (~4.5 km) parent sub-model for the GoM and a high-resolution (~1.5 km) child sub-model for the BoF. The tidal in-stream energy extraction in the model is parameterized in terms of nonlinear Rayleigh friction in the momentum equation. A suite of numerical experiments are conducted to determine the ranges of extractable tidal in-stream energy and resulting effects on the 3D tidal circulation over the Bay of Fundy and the Gulf of Maine (BoF-GoM) in terms of the Rayleigh friction coefficients. The 3D model results suggest that the maximum energy extraction in the Minas Passage increases tidal elevations and tidal currents throughout the GoM and reduces tidal elevations and circulation in the upper BoF, especially in the Minas Basin. The far-field effect of tidal energy extraction in the Passage on the 3D tidal circulation in the BoF-GoM is examined in two cases of harnessing tidal in-stream energy from (a) the entire water column and (b) the lower water column within 20 m above the bottom in the Passage. The 3D model results demonstrate that tidal in-stream energy extraction from the lower water column has less impact on the tidal elevations and circulation in the BoF-GoM than the energy extraction from the whole water column in the Minas Passage.
... Numerical studies of hydrodynamic processes in the Gulf of Maine during extratropical storm events fall into three categories: (1) wave models (Sucsy et al., 1993;Panchang et al., 2008), (2) tidesurge models (Bernier and Thompson, 2007), and (3) coupled circulation and wave models Chen et al., 2013). Only recently, fully-coupled circulation and wave models have been used to assess the contribution of wave-current interaction to coastal flooding Chen et al., 2013). ...
Elevated water level and large waves cause extensive damage and economic loss to coastal communities. An integrated atmosphere-ocean-coast modeling system that links physical processes with scales ranging from the open ocean to the surf zone has been developed for the Gulf of Maine. The modeling system includes a hydrodynamic model, a wave overtopping model and a sediment transport model. It is then applied to investigate and gain a comprehensive understanding of the following coastal processes: (1) the interaction between tide-surge, waves and bathymetry, (2) coastal flooding due to wave overtopping, and (3) sand transport. Both coastal flooding and sand transport rely on the accurate prediction of water level, waves, and currents at the coast. This work has demonstrated that the interactions between tide-surge, waves and bathymetry have a significant impact on coastal waves, circulation and water level; and the interactions exhibit strong temporal and spatial variability along the coast. The inclusion and appropriate representation of the interaction processes in numerical modeling is important for coastlines with complex configurations. The integrated modeling system has been applied to predict coastal flooding due to wave overtopping at the seawall in Scituate, Massachusetts. The capacity of the seawalls to protect coastal communities against flooding as sea level rises is investigated. It has been shown that seawalls will have to be elevated much more than the projected sea level rise to cope with future storms due to the presence of larger waves approaching the coast as depth increases. Sand transport and its response to different storm characteristics are closely linked to waves and currents. Local bathymetry and winds are the two most important factors determining waves, currents and sand transport. The role of wind-driven and wave-induced current for sand transport varies depending on water depth and coastline geometry. The wind-driven current dominates in shallow water, while the wave-induced current is more significant at headlands and around coastal structures and islands. Differences in net sand transport mainly result from different flow patterns due to the counterbalance between wind-driven and wave-induced currents.
... At the start of the ebb tide, the eddies that were created during the flood are advected out Minas Passage. The passage of these eddies is repeatable over the tidal cycles and can be seen in the current meter data as well as the model results.Overall, the flood/ebb behavior is consistent with other published results ( Greenberg, 1979;Sucsy et al., 2006 ). ...
... Numerical studies of hydrodynamic processes in the Gulf of Maine during extratropical storm events fall into three categories: (1) wave models (Sucsy et al., 1993;Panchang et al., 2008), (2) tide-surge models (Bernier and Thompson, 2007), and (3) coupled circulation and wave models Chen et al., 2013). Only recently, fully-coupled circulation and wave models have been used to assess the contribution of wave-current interaction to coastal flooding Chen et al., 2013). ...
The southern coast of the Gulf of Maine in the United States is prone to flooding caused by nor’easters. A state-of-the-art fully-coupled model, the Simulating WAves Nearshore (SWAN) model with unstructured grids and the ADvanced CIRCulation (ADCIRC) model, was used to study the hydrodynamic response in the Gulf of Maine during the Patriot’s Day storm of 2007, a notable example of nor’easters in this area. The model predictions agree well with the observed tide-surges and waves during this storm event. Waves and circulation in the Gulf of Maine were analyzed. The Georges Bank plays an important role in dissipating wave energy through the bottom friction when waves propagate over the bank from offshore to the inner gulf due to its shallow bathymetry. Wave energy dissipation results in decreasing significant wave height (SWH) in the cross-bank direction and wave radiation stress gradient, which in turn induces changes in currents. While the tidal currents are dominant over the Georges Bank and in the Bay of Fundy, the residual currents generated by the meteorological forcing and waves are significant over the Georges Bank and in the coastal area and can reach 0.3 m/s and 0.2 m/s, respectively. In the vicinity of the coast, the longshore current generated by the surface wind stress and wave radiation stress acting parallel to the coastline is inversely proportional to the water depth and will eventually be limited by the bottom friction. The storm surge level reaches 0.8 m along the western periphery of the Gulf of Maine while the wave set-up due to radiation stress variation reaches 0.2 m. Therefore, it is significant to coastal flooding.
... The resonant period of this system is slightly longer than the period of the dominant M2 tidal constituent and this area is well known for the large tide range in the upper bay. The node point for the oscillation is near the shelf break east of Georges Bank; however, this is complicated by other resonances parallel to the shelf that extend down to Boston can modify the resonance and have significant effects on tides as far as Boston [10]. The particular areas of interest were Minas Basin where the largest tide range occurs, and Minas Passage that connects Minas Basin with the upper Bay of Fundy (figure 11). ...
Abstract—This paper proposes an approach for combining
device-scale and basin-scale simulation methods to provide re-
alistic in-situ performance analysis of turbine arrays and with
the eventual goal of determining basin-scale effects from large
turbine arrays. The present state-of-the-art basin-scale simulation
methods represent turbines as sub-grid-scale objects, typically
using semi-empirical/semi-analytical turbine models. Device-scale
CFD simulation methods can resolve flows around turbines and
can predict turbine performance outside the idealized assump-
tions of analytical methods. Thus, combining the capabilities of
these two types of simulations is desirable for accurate in-situ
performance analysis with the correct influence of turbines on
the basin flow. The approach is to parameterize turbine thrust
and power using a reference velocity available to both types
of model. This is a volume average over a region in space
that can be resolved by the basin-scale model. The approach
is accurate provided both methods predict a consistent reference
velocity. This paper presents preliminary studies testing such
consistency for simplified channel scenarios, finding that as long
as the averaging volume has length scales twice the turbine
diameter, relative error in power is typically under ≈5%. When
applied to a complex real-world flow, the relative error was
larger. It is thought that at present, the method is suitable
for approximate power prediction and further improvement is
required for accurate turbine performance studies.
... When modifying the form drag in the upper bay, the resonance can be altered so that it becomes difficult to specify boundary conditions in a limited area model. Moreover, previous studies have shown that introducing features such as barrages that can modify the resonance and have significant effects on tides as far as Boston (Sucsy et al., 2006). Hence, the entire bay down to Cape Cod and extending offshore has been included in the model. ...
Accounting for the effects of subgrid features in a numerical model is a longstanding problem in surface water hydrodynamics. This problem arises in several ways: in many cases, objects in the flow are too small in scale to consider resolving, and in other cases, there can be tremendous savings in computer resources by limiting the resolution. At least two approaches can be used for estimating these effects. In a general method using double-averaging techniques, volume averages are calculated and include terms that arise from the stresses exerted by the subgrid objects. In another method primarily used to account for subgrid topographic variations, the subgrid data is incorporated directly into the model. The first method leads to the inclusion of form drag and is illustrated by studies of flow through vegetation on a river floodplain and tidal power potential of turbines placed in Minas Passage in the Bay of Fundy. The second method is illustrated by a study of tsunami runup on the west coast of Vancouver Island.
... The resulting capture is VC ¼ 99%, and the accuracy of the model is thus reasonably high considering the very large range of the tides in the area. It is also similar to other simulations of the tides in the area [Sucsy et al., 1993;Dupont et al., 2004;Karsten et al., 2008], and we argue that the model shows considerable skill in reproducing the structure of the tidal regime in the Gulf of Maine. ...
[1] The response of the Bay of Fundy and Gulf of Maine to large-scale tidal power plants and future sea-level rise is investigated using an established numerical tidal model. Free stream tidal turbines were simulated within the Bay of Fundy by implementing an additional bed friction term, Kt. The present-day maximum tidal power output was determined to be 7.1 GW, and required Kt = 0.03. Extraction at this level would lead to large changes in the tidal amplitudes across the Gulf of Maine. With future SLR implemented, the energy available for extraction increases with 0.5–1 GW per m SLR. SLR simulations without tidal power extraction revealed that the response of the semidiurnal tides to SLR is highly dependent on how changes in sea level are implemented in the model. When extensive flood defenses are assumed at the present-day coast line, the response to SLR is far larger than when land is allowed to (permanently) flood. For example, within the Bay of Fundy itself, the M2 amplitude increases with nearly 0.12 m per m SLR without flooding, but it changes with only 0.03 m per m SLR with flooding. We suggest that this is due to the flooding of land cells changing the resonant properties of the basin.
... Tidal amplitude and phase data were Ž . obtained from the larger Gulf of Maine model data set Sucsy et al., 1993 ( ) Some trial simulations with various friction specifications led to model failure at about 11 h into the simulation; investigation revealed that excessively high velocities were being produced in the vicinity of Tinker Island. However, each failed simulation provided a guide to an improved specification of the frictional coefficients, leading to Ž satisfactory results in about six trials. ...
An efficient mathematical modeling package called Aquaculture Waste Transport Simulator (AWATS) provides first-order estimates of the physical dispersion of finfish aquaculture wastes for regulatory purposes. The modeling strategy entails the utilization of a vertically averaged, two-dimensional flow model to produce flow-field information. This information is input to a particle-tracking waste transport model to simulate the resulting transport of wastes. Since earlier studies have shown that the transport modeling results are sensitive to the threshold shear stress at which settled fish-pen wastes are resuspended, fieldwork was conducted to improve the parameterization of erodibility in the transport model. Application of AWATS to aquaculture sites in coastal Maine (selected by the Maine Department of Environmental Protection) shows that it is a convenient tool in the regulatory process.
... Several researchers have studied and modelled tidal flows in the BoF over the years, but previous studies [ [5]] have not focused on modelling the tidal currents in detail nor on quantifying the associated renewable kinetic energy resources throughout the region. Several studies [ [13], [17]] have considered the changes in tidal hydrodynamics that would result from the construction of tidal barrages at various locations in the Bay. Because of the near-resonant state of the existing system, it has been shown that small changes in the geometry of the Bay, associated with the construction of a tidal barrage, could produce significant increases in tidal amplitudes as far away as Boston. ...
The Bay of Fundy, located between the Canadian Provinces of Nova Scotia and New Brunswick, is home to the world's largest tides and has long been identified as one of the world's premier resources of tidal energy. This paper describes the development of a high-resolution three-dimensional hydrodynamic model of tidal flows in the Bay of Fundy, and its application to help quantify and assess the kinetic energy resource throughout the Bay. Information on the scale and character of the tidal currents and the associated kinetic energy resource is presented herein for three of the most energetic parts of the Bay: near Long Island, Passamaquoddy Bay and Minas Passage (where a $70 million pre-commercial deployment of in-stream turbines is presently underway).
... Many previous researchers considered only the M 2 tidal constituent when studying the hydrodynamic impacts due to tidal power projects in the Bay of Fundy (Greenberg 1979;Sucsy et al. 1992;Greenberg et al. 1997). The M 2 constituent is certainly dominant and contributes over 80% of the total tidal energy in the upper Bay (Zhang et al. 2003). ...
The Bay of Fundy (BoF) in eastern Canada has long been recognised as one of the world's premier locations for the development of tidal power generating systems, since it has some of the world's largest tidal ranges. Several proposals have been made in recent years to find economical ways to harness the power of these extremely high tides, including constructing one or more tidal power lagoons in the upper part of the Bay. The tidal power lagoon concept involves temporarily storing seawater behind an impoundment dike and generating power by gradually releasing the impounded seawater through conventional low-head hydroelectric turbines. A tidal power lagoon will inherently modify the tides and tidal currents in the vicinity of the lagoon, and possibly induce effects that may be felt throughout the entire BoF and Gulf of Maine. The nature of these hydrodynamic impacts will likely depend on the size of the tidal lagoon, its location, and its method of operation. It is important to have reliable estimates of these potential impacts, since any changes in tidal hydrodynamics caused by a tidal lagoon may upset ecosystems that are well adapted to existing conditions. The scale and character of the potential hydrodynamic impacts due to tidal power lagoons operating in the BoF have not been previously investigated. This paper presents the results of study in which a 2D (depth-averaged) hydrodynamic model based on the TELEMAC modelling system was developed and applied to analyze, predict, and quantify the potential changes in tidal hydrodynamics (water levels, tidal range, circulation patterns and tidal currents) throughout the Bay of Fundy and Gulf of Maine due to the presence of a single tidal lagoon and multiple lagoons operating at various locations in the upper BoF. The sensitivity to changes in lagoon type, size, location, the number of lagoons, and their operating mode was also investigated and established. The final purpose of this novel study is to assist with decisions concerning the development of the vast tidal energy resources available in the Bay of Fundy, Canada.
... A number of studies reported that the tidal energy there can be exploited by using either the potential energy of the tidal range in the Minas Basin or the kinetic energy of the tidal current in Minas Passage. The environmental impacts based on the former approach have been investigated by many studies, including Garrett (1974), Garrett and Greenberg (1977), Greenberg (1977 Greenberg ( , 1979 Greenberg ( , 1983), Greenberg and Amos (1983), Sucsy et al. (1993) and Shaw et al. (2010), in which changes in physical characteristics of the tide, such as elevation and currents, in Gulf of Maine were examined by specifying reduced or no water flow into the Minas Basin. However, few studies discuss the impacts based on the presence of in-stream turbines in Minas Passage, except for Karsten et al. (2008), who found that a significant decrease of the tidal energy may lead to dramatic decrease of tidal level in the Minas Passage and Minas Basin, and thus affects a number of physical and biological processes. ...
The Minas Basin, the eastern end of the Bay of Fundy, is well known for its high tide ranges and strong tidal currents, which can be exploited to extract electricity power. The properties of the tidally-induced sediment transport in the Minas Basin, where significant changes in tidal processes may occur due to a recently proposed tidal power project, have been studied with a three-dimensional hydrodynamic model, an empirical bed load sediment transport model and surface sediment concentrations derived from the remotely-sensed images. The hydrodynamic model was evaluated against independent observational data, which include tidal elevation, tidal current (in the full water column and bottom layer), residual current profile and tidal asymmetry indicators. The evaluation shows that the model is in good agreement with the observations.
... The M 2 tide is the modeled tidal component in these experiments and is by far the most dominant constituent of the tidal regime in the Gulf of Maine and the Bay of Fundy (Garrett, 1972;Moody et al., 1984). The model reproduces present-day M 2 tides within 0.06 m in amplitude and 7°in phase (Sucsy et al., 1993). Results from paleotidal analyses (Table 3) are applied here to extract tidal amplification from the Holocene rise of mean high water along the Maine coast by subtracting half the tidal range that was obtained from the modeling experiments. ...
A suite of salt-marsh peat samples from four sites along the coast of Maine (Wells, Phippsburg, Gouldsboro, and Machiasport) has been analyzed using high-precision techniques to determine local relative sea-level trends and to evaluate proposed along-coast warping. A spatially variable set of relative sea-level records in Maine would have important implications for geophysical models that predict the response of the lithosphere during deglaciation and postglacial isostatic relaxation. These models are often at odds with observed relative sea-level indicators near the margins of former glaciation, including those from Maine. Assemblages of agglutinated benthic foraminifera occur in vertical zones on the surface of modern salt marshes in Maine and can be used to accurately locate former mean high water levels in cores. Additional tools in this study include accelerator mass spectrometer 14C dating of individual plant fragments and precise leveling of elevations. The amplification of M2 tidal range in the Gulf of Maine and the Bay of Fundy during the Holocene is modeled and applied to the mean high water data yielding best-estimate envelopes of mean tide level change for each location. Average long-term (thousands of years) mean tide level rise did not exceed ≈2 mm/yr at any time during the late Holocene at Wells, Phippsburg, and Machiasport. Between 4.5 and 3 ka (calibrated [cal]), the apparent rate of rise at Gouldsboro was higher than at any other site studied. This along-coast variation in the rate of mean tide level rise may reflect time of deglaciation, neotectonics, or differential isostatic adjustments. Between 8 and 5 ka (cal), only south-central Maine (Phippsburg) has a good record of relative sea-level change. At this locality, the rate of mean tide level rise was 5.0-8.8 mm/yr for the period 7.8-5.3 ka (cal), which may have resulted from collapse of a glacial forebulge. A slight acceleration of mean tide level rise has occurred during the past millennium in Gouldsboro and Machiasport. If 12 m downwarping in easternmost Maine occurred, as suggested in other publications, it must have happened prior to 5.7 ka (cal).
... When it is about 50 km south of Mount Desert Island, the 90 cophase line turns eastward again to end near Centreville, Nova Scotia. In general, the modeled coamplitude and cophase charts agree well with previous model studies (e.g., Greenberg 1979; Sucsy et al. 1993) and the tidal atlas of Moody et al. (1984) except in the upper Bay of Fundy where the model seems to underestimate the amplitude and over Nantucket Shoals where the modeled cophase lines tend to be too close to each other.Table 1 compares the modeled amplitude and phase with the atlas values of Moody et al. (1984) at 50 stations. Excluding the stations in the Bay of Fundy (* inTable 1) and stations VOLUME 30 J O U R N A L O F P H Y S I C A L O C E A N O G R A P H YFIG. 15. ...
The Princeton Ocean Model is used to study the circulation in the Gulf of Maine and its seasonal transition in response to wind, surface heat flux, river discharge, and the M2 tide. The model has an orthogonal-curvature linear grid in the horizontal with variable spacing from 3 km nearshore to 7 km offshore and 19 levels in the vertical. It is initialized and forced at the open boundary with model results from the East Coast Forecast System. The first experiment is forced by monthly climatological wind and heat flux from the Comprehensive Ocean Atmosphere Data Set; discharges from the Saint John, Penobscot, Kennebec, and Merrimack Rivers are added in the second experiment; the semidiurnal lunar tide (M2) is included as part of the open boundary forcing in the third experiment. It is found that the surface heat flux plays an important role in regulating the annual cycle of the circulation in the Gulf of Maine. The spinup of the cyclonic circulation between April and June is likely caused by the differential heating between the interior gulf and the exterior shelf/slope region. From June to December, the cyclonic circulation continues to strengthen, but gradually shrinks in size. When winter cooling erodes the stratification, the cyclonic circulation penetrates deeper into the water column. The circulation quickly spins down from December to February as most of the energy is consumed by bottom friction. While inclusion of river discharge changes details of the circulation pattern, the annual evolution of the circulation is largely unaffected. On the other hand, inclusion of the tide results in not only the anticyclonic circulation on Georges Bank but also modifications to the seasonal circulation.
... The bottom drag coefficient C d ¼ 6.4 Â 10 À3 following Greenberg (1979)[16] and Suscy et al. (1993) [17] ...
Power levels available from the kinetic energy of tidal flows can be significant in coastal or estuarine regions with relatively modest tidal ranges. For example, the central Maine coast, where the mean semi-diurnal tidal range is about 3 m, includes several river estuaries with narrow interconnecting passages where tidal currents exceed 2 m s−1. A numerical circulation model applied to this region shows that the vigorous tidal flows lead to available power peaks exceeding 3 kW per square meter of turbine aperture in several sites during a spring tide. At one promising location, the peak power density is 6.5 kW/m2 near the surface and the energy capacity in a 500 m2 section under mean tidal conditions is about 2700 MWh per year, sufficient to meet the average consumption needs of about 150 homes connected to an electrical grid capable of accepting the tidal power pulses and blending them with traditional sources.
... In a previous study, a 3-d model to simulate the circulation in the Gulf of Maine had been developed at the University of Maine (Sucsy et al. 1993). However, the computational resources required for 3-d simulations with fine resolution in a large region like Cobscook Bay (with an area of about 200 km2) would be extremely high and not warranted for the task at hand. ...
Net-pen aquaculture results in the introduction of excess fish food and fecal matter in coastal waters. These wastes may modify
the benthic environment. Mathematical models are developed in this study to simulate tidal and wind-driven currents, waves,
and the resulting dispersion of fish food and fecal matter in coastal Maine, a region where limited modelling studies have
been performed. Cobscook Bay and Toothacher Bay in Maine are studied in detail through the use of mathematical models and
field data. We find that a systematic, site-specific, step-by-step modeling strategy involving the use of numerical models
to simulate the overall hydrodynamic environment in combination with a waste-particle transport model can be an extremely
powerful method of determining a priori whether aquaculture operations will cause high rates of net-pen waste accumulation
at a particular site.
In this study, we employed a 3-D and two-way nested Regional Ocean Modeling System (ROMS) to address several important outstanding issues regarding tidal energy development in the Gulf of Maine. We investigated the impact of projected sea-level rise (SLR) on the energy resources of the region, and examined how tidal dynamics will be influenced by energy extraction and/or SLR. Further, we assessed whether the effect of SLR on the generation of tides in the ocean (hence at the boundary of the region) is significant in these assessments. We find that the impact of SLR exceeds the impact due to energy extraction in the Gulf of Maine - even when considering very large energy extraction, of order 3.0 GW, in the Minas Passage. Although results showed that energy extraction does not significantly increase the amplitude of the tides in the far-field, a drastic change in the Bay of Fundy (e.g. full blockage) can lead to considerably higher amplitudes of tides (around 35 cm, or 12%) in the western Gulf of Maine. As a result of 1 m SLR, the theoretical tidal energy resources in some areas, including the Bay of Fundy can increase noticeably while any significant change in extracted energy highly depends on the turbine technology.
The Gulf of Maine is frequently struck by Nor’easter storms during winter season. The strong wind produced by storm generates large waves and high surge, which may result in coastal inundation in low-lying areas along the coast when the storm peak coincides with high tide. In this paper, the state-of-the-art fully-coupled circulation and spectral wave model ADCIRC-UnSWAN was applied to investigate waves and circulation in the Gulf of Maine. The waves and surge level was well reproduced at wave buoy and tide gauge. While waves at offshore of Saco Bay reaches over 7.0 m at storm peak, it decreases rapidly when propagating into the bay, mainly caused by bottom friction and wave breaking. A clockwise circulation is identified at the offshore of Saco River. With the presence of waves, the clockwise circulation is greatly enhanced and moved further offshore. The surface elevation is also increased by 0.2m along the coast due to wave set-up.
Mariculture of the soft-shell clam Mya arenaria L. involves seeding juvenile shellfish on intertidal mudflats for grow-out. Laboratory studies have shown that constant current velocity affects shellfish growth. Few studies have determined the effect of tidal currents on shellfish growth in situ. Spot estimates of tidal currents can be generated with portable current meters and by measuring the erosion of Plaster of Paris hemispheres called clod cards placed in the current. Current velocities for Geographical Information System (GIS) coverages for entire estuaries can be estimated using numerical flow models. Although these different types of measurement have different relative advantages of cost, ease of describing large areas, and accuracy, each can be potentially used in evaluating sites for shellfish grow-out. Current velocities averaged over the flood tide were estimated by a numerical flow model and by clod cards for 16 locations at the same elevation in a bay in Eastern Maine and were compared with the annual shell increment of clams collected at the same locations. Statistical models included main effects and interactions between initial shell size, year of sample, and high-low current category estimated by clod cards or a numerical model. Models explained 57-58% of the variability in growth increment with initial shell size and year affecting growth more than current. Faster tidal currents resulted in 22-24% greater shell growth. Sites categorized as low flow had means for tidal currents (±SD) of 4.35 ± 0.37 cm/s and 2.99 ± 0.43 cm/s using the numerical model and clod cards, respectively. Least squares means (±SE) for the annual increment in shell length increment was 9.56 ± 0.247 mm for the low flow sites identified using the numerical model and 9.51 ± 0.274 mm for the low flow sites identified using clod cards. Sites categorized as high flow had current means (±SD) of 5.86 ± .62 cm/s using clod cards and 5.84 ± 0.46 cm/s using the numerical model and least squares means (±SE) for growth increment of 11.90 ± 0.32 and 11.70 ± 0.33 mm, respectively. The stimulatory effect of tidal currents on clam growth could be used in mariculture siting. Placing clod cards at specific intertidal locations at the same elevation could be used to estimate relative current velocities. Current velocities estimated using numerical models and displayed as GIS grids of entire regions will not have the same resolution as spot estimates from current meters or clod cards. However, grids can be used for siting if the grid cells are comparable in size to area to be seeded.
The transformation of natural tidal sea-level and currents is studied resulting from large-scale tidal power plant (TPP) dams in bays of the Sea of Okhotsk (SO). Some effects due to this transformation are estimated based on predictive modelling and a number of expected changes in amplitudes and phases, and spectral composition of tidal oscillations are described. Changes of morphometric properties of basins change the character of tidal motions even on significant distance from a dam. That is why, it is impossible to estimate this impact as usual boundary-value problems. The problem is solved based on “impedance” conditions on the open boundary of the model area, allowing to take into account the radiation of the additional perturbations induced by both waves reflected from the dam and nonlinear effects inside the area. In general, the transformation effects are proportional to the dam size and depend essentially on the dam location, the creation of which can change dissipative and resonance properties of the bays. The changes in tidal energetics of SO due to the dam construction are also considered to show noticeable reconstruction of horizontal energy fluxes and changes in the energy dissipation. Possible environmental consequences are related mainly to the transformation of tidal currents.
The nonlinear frictional behavior of two-dimensional (2-D) and three-dimensional (3-D) models are compared in this study of tides in the Bight of Abaco. The shallow depths and the existence of an extensive set of tidal elevation data (five astronomical and two overtide constituents at 25 stations) from Filloux and Snyder (1979) offer an excellent opportunity to compare the effects of different frictional formulations. In addition, previous modeling efforts in the bight have consistently overpredicted the M6 and generally overdamped the O1, K1, and S2 tides. The results indicate that although the 2-D and 3-D models may be calibrated to produce nearly identical responses for the dominant M2 tide, there are systematic differences in the responses of the primary overtides. These differences are explained using analytical expansions of the friction terms and are shown to be due to differences in the terms that are nonlinear in velocity and in water level. The investigation concludes that the overgeneration of M6 and the overdamping of secondary astronomical tides will occur in 3-D models as well as 2-D models. Although several causes for these problems were considered, improvement in these constituents could be achieved only by modifying the standard quadratic friction or flow-dependent eddy viscosity relations to reduce the nonlinear frictional effect relative to the linear frictional effect. The required modifications suggest the presence of a constant background velocity, residual turbulence field, or possibly the need for a more advanced frictional closure.
The tidal power available for electricity generation from in-stream turbines placed in the Minas Passage of the Bay of Fundy is examined. A previously derived theory is adapted to model the effect of turbine drag on the flow through the Minas Passage and the tidal amplitude in the Minas Basin. The theoretical maximum power production over a tidal cycle is determined by the product of the amplitude of the forcing tide in the Bay of Fundy and the undisturbed volumetric flowrate through the Minas Passage. Although the extraction of the maximum power will reduce the flowrate through the Minas Passage and the tides in the Minas Basin by over 30 per cent, a significant portion of the maximum power can be extracted with little change in tidal amplitude as the initial power generation causes only an increase in the phase lag of the basin tides. Two-dimensional, finite-element, numerical simulations of the Bay of Fundy–Gulf of Maine system agree remarkably well with the theory. The simulations suggest that a maximum of 7 GW of power can be extracted by turbines. They also show that any power extraction in the Minas Passage pushes the Bay of Fundy–Gulf of Maine system closer to resonance with the forcing tides, resulting in increased tidal amplitudes throughout the Gulf of Maine. Although extracting the maximum power produces significant changes, 2.5 GW of power can be extracted with a maximum 5 per cent change in the tidal amplitude at any location. Finally, the simulations suggest that a single turbine fence across the Minas Passage can extract the same power as turbines throughout the passage but that partial turbine fences are less efficient.
The glacially carved central coast of Maine is incised by river systems with interconnecting channels, offshore-trending submarine ridges, and narrow passages between nearshore islands and headlands. The tidal range exceeds 3 m, leading to complex and vigorous circulation patterns with strong flows in narrow channels, near river mouths, and between islands. The spongiform coastal morphology allows enhanced exchange between offshore waters, estuaries and internecine bays, resulting in rapid dispersal of nutrients, larvae and contaminants throughout the region. A fine-grid numerical circulation model has been used to examine the influences of the tides, river flows and winds on the dispersion of lobster larvae and pollutants in the nearshore and riverine environment. This paper describes the model application, presents a few salient features of the circulation patterns, and examines some implications for the coastal environment. For example, under realistic tides and variable southwest summer winds, about 80% of neutral near-surface particles introduced near the offshore islands (a proxy for stage IV lobster larvae from offshore sources) remain within a few km of the islands over a two-week period. On the other hand, a persistent, periodic sea breeze can remove more than two-thirds of the particles from the domain over the same period. Tidal mixing disperses pollutants entering the upper Kennebec River to the offshore and through internecine passages in about one week.
Increase in the M2 (principal lunar semi-diurnal) component of the tidal range is an important contributor to the postglacial rise of the high-tide level in the Gulf of Maine and the Bay of Fundy in addition to relative sea-level rise. The increase occurred as the shape of this semi-enclosed embayment changed with sea-level rise and its natural period approached resonance with the M2 tide. A three-dimensional tide model (3DENS) predicts the following M2 tidal ranges averaged for the Gulf of Maine/Bay of Fundy as a percentage of the present range: 54–59% at 7000 yrs B.P., 73% at 5000 yrs B.P., 78% at 4000 yrs B.P., 85% at 3000 yrs B.P., 94% at 2000 yrs B.P., and 98% at 1000 yrs B.P. With a predicted sea-level rise of 0.15–0.90 m by the year 2100, M2 tidal range may increase 0.3–1.9%.
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