High-resolution Hydrodynamic Model Research Articles

Modelling sea level surges in the Firth of Clyde, a fjordic embayment in south-west Scotland

Storm surges are an abnormal enhancement of the water level in response to weather perturbations. They have the capacity to cause damaging flooding of coastal regions, especially when they coincide with astronomical high spring tides. Some areas of the UK have suffered particularly damaging surge events, and the Firth of Clyde is a region with high risk due to its location and morphology. Here, we use a three-dimensional high spatial resolution hydrodynamic model to simulate the local bathymetric and morphological enhancement of surge in the Clyde, and disaggregate the effects of far-field atmospheric pressure distribution and local scale wind forcing of surges. A climatological analysis, based on 30 years of data from Millport tide gauges, is also discussed. The results suggest that floods are not only caused by extreme surge events, but also by the coupling of spring high tides with moderate surges. Water level is also enhanced by a funnelling effect due to the bathymetry and the morphology of fjordic sealochs and the River Clyde Estuary. In a world of rising sea level, studying the propagation and the climatology of surges and high water events is fundamental. In addition, high-resolution hydrodynamic models are essential to forecast extreme events and to prevent the loss of lives, or to plan coastal defences solutions.

Hydrodynamic modelling of coastal seas: the role of tidal dynamics in the Messina Strait, Western Mediterranean Sea

Abstract. This work explores the importance of considering tidal dynamics when modelling the general circulation in the Messina Strait, a narrow passage connecting the Tyrrhenian and the Ionian subbasins in the Western Mediterranean Sea. The tides and the induced water circulation in this Strait are among the most intense oceanographic processes in the Mediterranean Sea. The quantification of these effects can be particularly relevant for operational oceanographic systems aimed to provide short-term predictions of the main hydrodynamics in the Western Mediterranean subbasins. A numerical approach based on the use of a high-resolution hydrodynamic model was followed to reproduce the tides propagation and the wind-induced and thermohaline water circulation within the Strait and in surrounding areas. A set of numerical simulations was carried out to quantify the role of the Strait dynamics on the larger-scale water circulation. The obtained results confirmed the importance of a correct representation of the hydrodynamics in the Messina Strait even when focusing on predicting the water circulation in the external sea traits. In fact, model results show that tidal dynamics deeply impact the reproduction of the instantaneous and residual circulation pattern, waters thermohaline properties and transport dynamics both inside the Messina Strait and in the surrounding coastal and open waters.

The urban marine environment of Singapore

The island Republic of Singapore lies on the nexus between the Pacific and Indian Oceans, in the equatorial tropics of the South China Sea. With her strategic geographic location and natural harbour, Singapore has grown into a major global transhipment hub, with an estimated 130,000 vessel arrivals per year navigating within 600 km2 of sea space. The coastal environment around Singapore has also changed dramatically over the last 50 years as a result of ambitious urban coastal development projects to accommodate aspirations of a population of 5.54 million people settled within a land area of 718.3 km2. This paper provides a review of the physical environment of the marine waters around Singapore. As characteristic of urban coastal cities, anthropogenic sources of contaminants have been reported in the coastal environment. Overall, patterns of environment contamination reflect the changing social and economic activity, and evolving awareness of environment impacts of different pollutants. Early studies consisted of spatially and temporally limited sampling efforts which were not always informative of causative factors. However, recent introduction of advanced chemical detection tools and high resolution hydrodynamic modelling has opened the door for new studies to revisit and understand the dynamic nature of our physical environment.

A high resolution hydrodynamic model system suitable for novel harmful algal bloom modelling in areas of complex coastline and topography

Fjordic coastlines provide sheltered locations for finfish and shellfish aquaculture, and are often subject to harmful algal blooms (HABs) some of which develop offshore and are then advected to impact nearshore aquaculture. Numerical models are a potentially important tool for providing early warning of such HAB events. However, the complex topography of fjordic shelf regions is a significant challenge to modelling. This is frequently compounded by complex bathymetry and local weather patterns. Existing structured grid models do not provide the resolution needed to represent these coastlines in their wider shelf context. In a number of locations advectively transported blooms of the ichthyotoxic dinoflagellate Karenia mikimotoi are of particular concern for the finfish industry. Here were present a novel hydrodynamic model of the coastal waters to the west of Scotland that is based on unstructured finite volume methodology, providing a sufficiently high resolution hydrodynamical structure to realistically simulate the transport of particles (such as K. mikimotoi cells) within nearshore waters where aquaculture sites are sited. Model–observation comparisons reveal close correspondence of tidal elevations for major semidiurnal and diurnal tidal constituents. The thermohaline structure of the model and its current fields are also in good agreement with a number of existing observational datasets. Simulations of the transport of Lagrangian drifting buoys, along with the incorporation of an individual-based biological model, based on a bloom of K. mikimotoi, demonstrate that unstructured grid models have considerable potential for HAB prediction in Scotland and in complex topographical regions elsewhere.

Mississippi waters reaching South Florida reefs under no flood conditions: synthesis of observing and modeling system findings

In August 2014, in situ measurements revealed an intense salinity drop impacting South Florida coral reefs, between Pulley Ridge (Southwest Florida Shelf) and the Florida Keys. The low salinity waters had a surface signal of 32 (down from 35.2) and extended over a 15–20-m deep lens. Satellite observations showed that this abrupt drop in salinity was due to a southeastward export of Mississippi River waters from the Northern Gulf of Mexico (GoM), revealing strong interaction between coastal and oceanic flows. Unlike previous events of marked long-distance Mississippi water export, this episode is not associated with Mississippi flooding conditions, which makes it a unique study case. We have developed a high-resolution (~2 km) comprehensive hydrodynamic numerical model of the GoM to study the conditions that controlled the 2014 Mississippi River water export episode. It is based on the Hybrid Coordinate Ocean Model (HYCOM) and assimilates remotely sensed altimetry and sea surface temperature observations, to ensure that the simulated upper-ocean is realistic. This regional model has a detailed representation of coastal physics (especially river plume dynamics) and employs high-frequency river discharge and atmospheric forcing. The combined use of the simulation and observations reveals a unique pathway that brought Mississippi waters first eastward along the Northern GoM continental shelf, under prevailing winds and the presence of an anticyclonic Loop Current eddy, then southward along the edge of the West Florida Shelf, before reaching the deep GoM. Unlike usually observed, the offshore advection of Mississippi River waters thus took place far from the Delta area, which is another specificity of the 2014 episode. Finally, in the Florida Straits, Mississippi waters were advected from the deep ocean to the continental shelf under the influence of both deep sea (particularly a cyclonic Loop Current frontal eddy) and shelf flows (wind-induced Ekman transport). The simulation, in tandem with data, thus helped analyze processes that are likely to affect the connectivity between reefs in the southern Florida region (Florida Keys, Dry Tortugas, Pulley Ridge) and remote areas (Mississippi Delta), as well as the local connectivity between neighboring reefs.

The wind-measuring system in the Gulf of Oristano: a support for coastal-scale oceanographic applications

ABSTRACTThis paper describes a wind-measuring system (WMS) in the coastal area of the Gulf of Oristano, Sardinia, Italy. In this area, an oceanographic forecasting system based on a high-resolution finite-element hydrodynamic and wave model is operative. The system is forced by the wind fields provided by medium resolution (about 0.1×0.1 deg) atmospheric models. The high spatial resolution of the oceanographic prediction system (between 50 m and 1 km) is not accompanied by a similar resolution for atmospheric forcing. Therefore, the implementation of a WMS, aimed at accurately measuring the three-dimensional wind components, provides an essential tool to evaluate both the performance of the atmospheric models used to force the oceanographic models and the sensitivity of the oceanographic models to wind forcing of different qualities and spatial resolutions, the experimental fields included. This paper describes the WMS, the data collected and the geophysical quantities obtained from the time series of the three components of the wind sampled at high frequency. It also shows the results of comparisons between the experimental wind data and those from the atmospheric model at present used to force the oceanographic forecasting system. The information obtained from the WMS is unique, spanning from the spatial and temporal variability of the wind over the area of investigation to the evaluation of the basic quantities characterising the atmospheric boundary layer.

Real-time species distribution models for conservation and management of natural resources in marine environments

Species distribution models in marine environments typically use static variables, partly due to the limited availability of fine-resolution dynamic predictor variables and sufficiently detailed species abundance data. Our aim was to describe and quantify the dynamic coupling between the distribution of marine species (seabirds) and the natural variability of their habitat in real time through the combination of a high-resolution hydrodynamic model, aerial digital surveys and real-time species distribution modelling. We used a 2-step (delta) generalized additive model at 500 m spatial resolution for assessment and prediction of the changing patterns of wintering red-throated divers (RTDs) Gavia stellata in the outer Thames estuary, United Kingdom. Our dynamic species distribution models successfully resolved the major oscillations in the distribution of RTDs and confirmed their tight association with frontal zones where the probability of prey encounter was higher. The relative model standard errors (%) were generally below 30% in the high-density areas. Area under the curve (AUC) values indicated that the models were capable of distinguishing presence from absence about 75% of the time. The predictive power of the achieved distribution models made it possible to accurately identify areas where RTDs were con- centrated. Comparisons between visual aerial and digital stills aerial surveys documented that, in spite of similar patterns, the aerial digital surveys generally recorded significantly higher densities of RTDs than the visual aerial surveys. This study demonstrates how marine distribution models with assimilation of habitat variables from a well-calibrated fine-resolution hydrodynamic model coupled with the use of digital aerial surveys can facilitate the capture of detailed associations between seabirds and their dynamic habitats.

Improving Modeling of Tides on the Continental Shelf off the West Coast of India

ABSTRACT Testut, L. and Unnikrishnan, A.S., 2016. Improving modeling of tides on the continental shelf off the west coast of India. Global tidal solutions are sometimes inaccurate in coastal regions. This is particularly true in some regions of the northern Indian Ocean, which are characterized by wide continental shelves and large tidal ranges. We show that these global solutions are inaccurate on the shelf region off Mumbai, off the west coast of India. In this region, the shelf is very wide, and it opens into the Gulf of Khambhat, where large tides are observed. Moreover, in regions of large semidiurnal tides in the Bay of Bengal, such as the head Bay, Gulf of Martaban, etc., global tidal solutions are not accurate. In the present work, we focus on the shelf region off the west coast of India. We used a new approach in developing a high-resolution hydrodynamic tidal model for the inner shelf region (8°N to 22°N). The open boundary of the model is aligned to the altimetry tracks, which allowed us to pre...

Effects of Morphological Change on Fluvial Flood Patterns Evaluated by a Hydro-geomorphological Model

High aggradation and degradation in a river induced by last flood event will respectively raise and decrease the risk of an upcoming flood event. However, this point is likely to be ignored or is not fully considered in some 2D fluvial flood models. To address this problem, this work develops a 2D high-resolution hydrodynamic model coupled with the sediment transport and the river bed evolution models. The modelling system is within the framework of a Godunov-type finite volume scheme. GPU technique is applied to accelerate the computation by more than 10 times, comparing to the CPU counterpart. After being validated against an experimental benchmark test, the model is applied to simulate the effects of the morphological change on flood patterns for the Bayangaole Reach of Yellow River, China. The results indicate that the effect of perturbed bed could be of significance for the fluvial flood over movable bed. It is therefore suggested to take into account when evaluating the flood risk in this case.

A biophysical model for simulating early life stages of sardine in the Iberian Atlantic stock

The Iberian sardine (Sardina pilchardus) is a traditional fishery in western Iberia that is economically important in Portugal and in Galicia (NW Spain). The International Council for the Exploration of the Seas (ICES) advice for the sardine in regions VIII and IXa in 2013 indicated that the biomass has decreased since 2006 and recruitment has been below the long term average since 2005. Recruitment is very variable, so it is important to understand the underlying processes driving this variation in order to manage the fishery effectively. In this study, a biophysical model was used to simulate the early life (egg and larval) stages of sardine. A high resolution hydrodynamic model for North and Northwest Iberia was used to force a Lagrangian Individually-Based Model (IBM) that simulated advection and dispersion (both horizontal and vertical) and included some biological behaviour. A Lower Trophic Level (LTL) model coupled to the hydrodynamic model was also used to get some insight on recruitment for years 2006–2007. Additionally, since in this area there are two different spawning grounds that could be associated with two eventually different populations, we have tried to show how the model can be used for giving insight on stock connectivity and therefore can contribute to stock delineation.

Probabilistic approach of water residence time and connectivity using Markov chains with application to tidal embayments

Markov chain analysis was recently proposed to assess the time scales and preferential pathways into biological or physical networks by computing residence time, first passage time, rates of transfer between nodes and number of passages in a node. We propose to adapt an algorithm already published for simple systems to physical systems described with a high resolution hydrodynamic model. The method is applied to bays and estuaries on the Eastern Coast of Canada for their interest in shellfish aquaculture. Current velocities have been computed by using a 2 dimensional grid of elements and circulation patterns were summarized by averaging Eulerian flows between adjacent elements. Flows and volumes allow computing probabilities of transition between elements and to assess the average time needed by virtual particles to move from one element to another, the rate of transfer between two elements, and the average residence time of each system. We also combined transfer rates and times to assess the main pathways of virtual particles released in farmed areas and the potential influence of farmed areas on other areas. We suggest that Markov chain is complementary to other sets of ecological indicators proposed to analyse the interactions between farmed areas — e.g., depletion index, carrying capacity assessment. Markov chain has several advantages with respect to the estimation of connectivity between pair of sites. It makes possible to estimate transfer rates and times at once in a very quick and efficient way, without the need to perform long term simulations of particle or tracer concentration.

A real‐time pluvial flood forecasting system for Castries, St. Lucia

AbstractIn the last decade, real‐time flood forecasting has become a more feasible approach to reducing the impacts of flooding in urban areas. Two key tools in this context are high resolution hydrodynamic modelling in combination with accurate hydrological forcing. In some cases, when it is not possible to produce such accurate flood forecasts based on high resolution models and data, it may nevertheless be possible to use the resources currently available, accepting that there is a greater degree of uncertainty involved. This paper demonstrates the feasibility of a remotely controlled, real‐time, pluvial flood forecasting system for Castries, St. Lucia that utilises the limited data available locally. The results from the study suggest that although Global Forecast System (GFS) rainfall data may be considered coarse for urban applications, there is still a significant amount of skill and usability after it is postprocessed and used in combination with observed rainfall data. Evidence from the study also suggests that the use of images from different sources is invaluable for 2D overland model calibration and validation in urban areas. Conclusions from the study are potentially transferable to other sites in similar data‐scare and resource‐limited locations.

Understanding the Geophysical Sources of Uncertainty for Satellite Interferometric (SRTM)-Based Discharge Estimation in River Deltas: The Case for Bangladesh

Like most river deltas, Bangladesh represents a geographically small region with numerous crisscrossing rivers. The total number of rivers in Bangladesh exceeds 300, of which 57 rivers are transboundary. Given the widespread unavailability of flow data across the entire river basins of Ganges, Brahmaputra, and Meghna, combined with a declining measurement network and political challenges of sharing the data, satellite remote sensing of discharge has recently become a viable alternative. This study was motivated by the need to understand the geophysical sources of uncertainty of satellite interferometric-based discharge estimation in Bangladesh. A consequential goal of this study was to contextualize the understanding as a function of river’s geophysical characteristics (river width, reach averaging length, and bed/water slope) and also to explore a pragmatic approach to uncertainty reduction using water level climatology. Discharge was estimated according to the slope-area (Manning’s) method using elevation data from Shuttle Radar Topography Mission (SRTM). A high-resolution hydrodynamic (HD) model was accurately calibrated to simulate water level and flow dynamics along the river reaches of the river network and serve as reference for comparison with satellite-based estimates. It was found that satellite interferometric (SRTM)-based discharge estimates yielded estimation error variance an order smaller than the natural flow variability only if the river width was at least three times larger the width of the native resolution of satellite elevation data. Rivers narrower than this width (for SRTM, this cutoff is 270 m) yielded a coefficient of variation larger than 1 due to contamination of land elevation data in hydraulic parameter calculations. It was also found that water level climatology can be useful in significantly reducing the estimation uncertainty for these narrow rivers. While reach averaging length appeared insensitive to accuracy for wide rivers (width ${\bf \gt\! 1\nbsp\hbox{km}}$ ), a few rivers seemed to have an optimal reach averaging length at which the highest accuracy is obtained. Finally, it was found that if reach-averaged hydraulic parameters (area, slope, and radius) are used for the calculation of reach-averaged discharge, the needed linear (bias) correction factors, although unique and arbitrary for each river reach, can improve accuracy of flow simulations.

Current-Oriented Swimming by Jellyfish and Its Role in Bloom Maintenance

Cross-flows (winds or currents) affect animal movements [1-3]. Animals can temporarily be carried off course or permanently carried away from their preferred habitat by drift depending on their own traveling speed in relation to that of the flow [1]. Animals able to only weakly fly or swim will be the most impacted (e.g., [4]). To circumvent this problem, animals must be able to detect the effects of flow on their movements and respond to it [1, 2]. Here, we show that a weakly swimming organism, the jellyfish Rhizostoma octopus, can orientate its movements with respect to currents and that this behavior is key to the maintenance of blooms and essential to reduce the probability of stranding. We combined in situ observations with first-time deployment of accelerometers on free-ranging jellyfish and simulated the behavior observed in wild jellyfish within a high-resolution hydrodynamic model. Our results show that jellyfish can actively swim countercurrent in response to current drift, leading to significant life-history benefits, i.e., increased chance of survival and facilitated bloom formation. Current-oriented swimming may be achieved by jellyfish either directly detecting current shear across their body surface [5] or indirectly assessing drift direction using other cues (e.g., magnetic, infrasound). Our coupled behavioral-hydrodynamic model provides new evidence that current-oriented swimming contributes to jellyfish being able to form aggregations of hundreds to millions of individuals for up to several months, which may have substantial ecosystem and socioeconomic consequences [6, 7]. It also contributes to improve predictions of jellyfish blooms' magnitude and movements in coastal waters.

Connectivity patterns of coastal fishes following different dispersal scenarios across a transboundary marine protected area (Bonifacio strait, NW Mediterranean)

The Strait of Bonifacio constitutes one of the rare transboundary Marine Protected Areas (MPA) of the Mediterranean Sea (between Sardinia, Italy and Corsica, France). Based on the hypothesis that no-take zones will produce more fish larvae, compared to adjacent fished areas, we modeled the outcome of larvae released by coastal fishes inside the no-take zones of the MPA in order to: (1) characterize the dispersal patterns across the Strait of Bonifacio; (2) identify the main potential settlement areas; (3) quantify the connectivity and the larval supply from the MPAs to the surrounding areas. A high resolution hydrodynamic model (MARS 3D, Corse 400 m) combined to an individual based model (Ichthyop software) was used to model the larval dispersal of fish following various scenarios (Pelagic Larval Duration PLD and release depth) over the main spawning period (i.e. between April and September). Dispersal model outputs were then compared with those obtained from an ichthyoplankton sampling cruise performed in August 2012. There was a significant influence of PLD to the connectivity between coastal areas. The synchronization between spawning and hydrodynamic conditions appeared to be determinant in the larval transport success. Biotic and abiotic parameters affecting the dispersal dynamic of fish larvae within the Strait of Bonifacio were identified and synthesis maps were established as a tool for conservation planning.

Advective loss of overwintering Calanus finmarchicus from the Faroe–Shetland Channel

The flow of deep water from the Norwegian Sea to the North Atlantic via the Faroe–Shetland Channel is one of the critical bottlenecks in the meridional overturn circulation. It is also a flow that potentially carries with it a large number of the overwintering copepod, Calanus finmarchicus, a regionally important secondary producer. Using a high resolution hydrodynamic model, MIKE 3 FM, we simulate the overflow of deep water and estimate the associated loss rate of C. finmarchicus as a function of the water depth strata within which they reside. We estimate a net advective loss from the Norwegian Sea population of 80±10kt carbon bound in lipids of C. finmarchicus biomass per year, a number that constitutes about 50% of the total overwintering population. Estimates of water mass characteristics and particle tracking suggest that the fate of individuals transported in the overflowing water is to be entrained into warmer waters of the North Atlantic Basin, a habitat that appears to be unsuitable for successful overwintering.

Thermal Impact from a Thermoelectric Power Plant on a Tropical Coastal Lagoon

Tropical coastal areas are sensitive ecosystems to climate change, mainly due to sea level rise and increasing water temperatures. Furthermore, they may be subject to numerous stresses, including heat releases from energy production. The Urias coastal lagoon (SE Gulf of California), a subtropical tidal estuary, receives cooling water releases from a thermoelectric power plant, urban and industrial wastes, and shrimp farm discharges. In order to evaluate the plant thermal impact, we measured synchronous temperature time series close to and far from the plant. Furthermore, in order to discriminate the thermal pollution impact from natural variability, we used a high-resolution hydrodynamic model forced by, amongst others, cooling water release as a continuous flow (7.78 m3 s−1) at 6 °C overheating temperature. Model results and field data indicated that the main thermal impact was temporally restricted to the warmest months, spatially restricted to the surface layers (above 0.6 m) and distributed along the shoreline within ∼100 m of the release point. The methodology and results of this study can be extrapolated to tropical coastal lagoons that receive heat discharges.

Spatial patterns of warming off Western Australia during the 2011 Ningaloo Niño: Quantifying impacts of remote and local forcing

In austral summer 2011, an unprecedented Ningaloo Niño event occurred off the west coast of Australia, with sea surface temperature anomalies reaching 5°C and significant impacts on marine ecosystems. In this study, a high resolution (~2km) hydrodynamic model (Regional Ocean Modeling System) is used to simulate the variations in the near-surface temperature in the region from 2009 through mid-2011. Model results indicate that the peak temperatures in the broad mid-west coast of Australia during the event are predominantly due to poleward advection of warmer, tropical water (≈2/3 contribution). In addition, positive air–sea heat flux into the ocean also contributes (≈1/3 contribution) to the rise in temperature. The anomalous advection of warm water is caused by changes in the poleward flowing Leeuwin Current due to both local and remote wind forcing. In early 2011, the Leeuwin Current intensified owing to remote forcing by the equatorial easterly wind anomalies in the Pacific Ocean associated with the 2010–2011 La Niña. In addition, the southerly winds off the west coast of Australia weakened, allowing the Leeuwin Current to further intensify in speed at the peak of the event. Concurrently, the inshore, equatorward Capes Current was suppressed and reversed direction. The poleward flow over the shelf contributed to near-shore warming in contrast to cooling by upwelling and equatorward advection from the Capes Current in previous years.

Understanding macroalgal dispersal in a complex hydrodynamic environment: a combined population genetic and physical modelling approach.

Gene flow in macroalgal populations can be strongly influenced by spore or gamete dispersal. This, in turn, is influenced by a convolution of the effects of current flow and specific plant reproductive strategies. Although several studies have demonstrated genetic variability in macroalgal populations over a wide range of spatial scales, the associated current data have generally been poorly resolved spatially and temporally. In this study, we used a combination of population genetic analyses and high-resolution hydrodynamic modelling to investigate potential connectivity between populations of the kelp Laminaria digitata in the Strangford Narrows, a narrow channel characterized by strong currents linking the large semi-enclosed sea lough, Strangford Lough, to the Irish Sea. Levels of genetic structuring based on six microsatellite markers were very low, indicating high levels of gene flow and a pattern of isolation-by-distance, where populations are more likely to exchange migrants with geographically proximal populations, but with occasional long-distance dispersal. This was confirmed by the particle tracking model, which showed that, while the majority of spores settle near the release site, there is potential for dispersal over several kilometres. This combined population genetic and modelling approach suggests that the complex hydrodynamic environment at the entrance to Strangford Lough can facilitate dispersal on a scale exceeding that proposed for L. digitata in particular, and the majority of macroalgae in general. The study demonstrates the potential of integrated physical-biological approaches for the prediction of ecological changes resulting from factors such as anthropogenically induced coastal zone changes.

Coupling of Sea Level Rise, Tidal Amplification, and Inundation

Abstract With the global sea level rising, it is imperative to quantify how the dynamics of tidal estuaries and embayments will respond to increased depth and newly inundated perimeter regions. With increased depth comes a decrease in frictional effects in the basin interior and altered tidal amplification. Inundation due to higher sea level also causes an increase in planform area, tidal prism, and frictional effects in the newly inundated areas. To investigate the coupling between ocean forcing, tidal dynamics, and inundation, the authors employ a high-resolution hydrodynamic model of San Francisco Bay, California, comprising two basins with distinct tidal characteristics. Multiple shoreline scenarios are simulated, ranging from a leveed scenario, in which tidal flows are limited to present-day shorelines, to a simulation in which all topography is allowed to flood. Simulating increased mean sea level, while preserving original shorelines, produces additional tidal amplification. However, flooding of adjacent low-lying areas introduces frictional, intertidal regions that serve as energy sinks for the incident tidal wave. Net tidal amplification in most areas is predicted to be lower in the sea level rise scenarios. Tidal dynamics show a shift to a more progressive wave, dissipative environment with perimeter sloughs becoming major energy sinks. The standing wave southern reach of the bay couples more strongly back to the central portion of the bay, in contrast to the progressive wave northern reach of the bay. Generation of the M4 overtide is also found to vary between scenarios and is a nonnegligible contributor to net changes in high water elevation.