Accurate characterisation of fluid flow at tidal energy sites is critical for cost effective Tidal Energy Converter (TEC) design in terms of efficiency and survivability. The standard instrumentation in tidal site characterisation has been Diverging acoustic-Beam Doppler Profilers (DBDPs) which remotely measure the flow over a range of scales, resolving up to three velocity vectors. However, they are understood to have several drawbacks particularly in terms of characterising turbulent aspects of the flow. This characterisation is generally based upon a small number of key transient metrics, the accuracy of which directly impacts TEC designs. This work presents an optimisation and performance assessment of newly available Single Beam Doppler Profilers (SBDPs) mounted on a commercial-scale tidal turbine at mid-channel depth in a real operating environment. It was hypothesised that SBDPs would have advantages over DBDPs for site characterisation, in terms of reduced random error, reduced uncertainty in turbulence intensities and the ability to quantify the structure of the turbulent flow. The relationship between random error, sensor orientation and flow speed is quantified for both single and diverging beam sensor types. Random error was found to increase with increasing flow velocity as a power law, the slope of which varies for different sensor orientations. Quantification of noise offers a practical method to correct turbulence metrics. To enable the use of multiple acoustic sensors mounted in close proximity, interference was quantified and mitigation techniques examined. Cross-talk between sensors of the same type were generally shown to bias measurements towards zero. In the presence of alternate types of acoustic sensors, interference caused an increase in standard deviation of velocity results. Implementing a timing offset control mechanism was able to mitigate this effect. This work has achieved a greater understanding of the drivers (spatial separation, inclination angle, pulse power) and effects on measurements of interference along with ambient-noise for users of acoustic instruments. Lessons learned of value to the industry, as site characterisation work intensifies ahead of next generation commercial scale devices, are presented. Mid-channel depth mounted SBDPs were found to have advantages over seabed mounted DBDPs in resolving the key turbulent flow metrics. SBDPs were able to resolve integral length-scales of turbulence that show an anisotropic ratio of scales as predicted from theory and in work at similar sites, while the DBDPs results were similar for all directions. Turbulence intensity measurements were found to be similar after noise correction, with the SBDPs more able to accurately capture the turbulence dissipation rate. This evidence suggests that SBDP arrays present a significant improvement over bottom mounted DBDPs in discerning information about the nature of the turbulent flow, and thus future site characterisation work should consider the use of SBDPs alongside bottom mounted DBDPs for this purpose.

No description available.

Dwarf galaxies may form in the tidal tails of galaxy interactions. If these tidal dwarf galaxies (TDGs) detach from their parent galaxies, then an independent dwarf galaxy emerges. However, the lifespan of such objects is uncertain. Using IR, UV, and optical images, we conducted a search for detached TDGs from a set of 40 interacting galaxy pairs in the local Universe, and a control sample of 37 spiral galaxies. Both samples include 3.6 micron, 4.5 micron, 8 micron, and NUV images. In an earlier study (Smith et al. 2016), we used the IRAF daofind software (Stetson 1987) to search for star-forming regions within the main bodies of these galaxies and in their extended tidal tails. In the current study, we used the same procedure to search for such regions outside of the galaxies. We used two spatial scales to search for the TDGs, 1 kiloparsec and 2.5 kiloparsecs radius, and then used Spitzer infrared colors to identify and eliminate possible foreground stars and background quasars. The remaining objects may be detached tidal dwarfs that formed in the tails and then escaped. After comparing our observational results of the number of TDGs surrounding our interacting galaxies to the numbers around normal spirals, we find no significant difference in the number of candidate TDGs near interacting galaxy pairs compared to normal spiral galaxies. The most promising TDG candidates will be targeted by follow-up spectroscopic observations to determine their redshifts, metallicities, and their velocity structures. Younger TDGs are expected to have higher metallicities relative to their masses compared to primordial dwarf galaxies, relative to the standard mass-luminosity relationship for galaxies. Furthermore, TDGs should lack dark matter in contrast to primordial dwarf galaxies.

Understanding species-specific physiological tolerances to environmental extremes is key in determining the factors that contribute to regulating species distribution. This understanding will aid in determining which species will manage to thrive in a changing global climate. According to the IPCC (2013) it is expected that, in the coming years, many different types of abiotic factors will change as a result of global climate change. The intertidal habitat is a model habitat for studying environmental extremes as it is located at the interface between the marine and terrestrial environments, making it one of the most stressful marine habitats. It is characterized by a 24 hr light: dark cycle and a 12.4 tidal ebb and flow that exposes animals inhabiting this habitat to a wide array of aerial-associated stressors such as changes in temperature, aerial exposure, low oxygen or hypoxic conditions and desiccation stress. Sessile organisms such as marine mussels of the genus Mytilus, are an ideal study species for studying physiological tolerance at the environmental extremes of the intertidal habitat. In particular, M. trossulus and M. galloprovincialis are an excellent study system for examining physiological tolerance at environmental extremes due to the recent change in biogeographic range of both species. M. galloprovincialis, a native of the Mediterranean, has been taking over the coast of California and has been displacing the heat sensitive native M. trossulus. The effects of salinity stress and heat stress on the physiologies of these species have been investigated by Braby and Somero (2006a and 2006b), Tomanek and Zuzow (2010) and Tomanek et al. (2012). The results of these studies indicate that the invasive M. galloprovincialis is more heat tolerant but is sensitive to hyposalinity while the reverse is true for the native M. trossulus.. The next logical environmental stress to study is low tide or aerial-emersion as both species can be found both tidally and subtidally. According to Grieshaber et al. (1994) and Müller et al. (2012) Mytilus edulis mussels have mechanisms for mitigating aerial-emersion hypoxia; however, very few studies have been performed using the study system of M. trossulus and M. galloprovincialis in regard to aerial-emersion hypoxia. This study aimed to observe the responses of both M. trossulus and M. galloprovincialis to aerial-emersion hypoxic stress or low tide. The study also looked to see if the recent habitat history (tidal or subtidal) can play a role in the response of the mussels to hypoxia. The results of the experiment indicate that the invasive M. galloprovincialis may be less sensitive to hypoxic stress when compared to the native M. trossulus. This difference in sensitivity may be due to the difference in mechanisms of energy metabolism proteins and proteostasis proteins used to mitigate the effects of hypoxic stress. Moreover, tidal acclimation appears to better prepare the mussels for subsequent aerial exposure in both species, possibly based upon the principles of stress-hardening outlined by Kültz (2005).

The Upper Mississippian Hinton, Princeton, and Bluestone formations of southern West Virginia constitute a wedge of strata that filled the Appalachian basin over a ~7 million year time interval. Seventeen transgressive-regressive sequences comprise the study interval in the basin depocenter. Five sequence types defined by the degree of incision and the thickness/ character of dominant facies include: 1) major incised valley-fill to coastal plain, 2) major incised valley-fill to deltaic, 3) minor incised valley-fill, 4) coastal plain, and 5) marine-dominated sequences. Transgressive and highstand deposits within several sequences contain tidal rhythmites. The prodeltaic Pride Shale member (Bluestone Formation) preserves a hierarchy of submillimeter-to meter-scale cycles that reflect a spectrum of tidal periodicities. The abbreviated character of these microlaminated rhythmites is suggestive of a distal, subtidal setting wherein neap tides were of insufficient strength to transport sand/ silt. Decimeter-scale bundling of semimonthly cycles is ascribed to seasonal fluvial discharge. Meter-scale, multi-year cycles may reflect the 18.6-year lunar nodal cycle. Sequence development likely reflects fourth-order (~400 k.y.), Gondwanan glacioeustatic cycles. The character and relative stratigraphic position of paleoclimatic indicators within the sequences suggests a link between eustasy and patterns of global-scale atmospheric circulation. Calcic vertisols and lacustrine carbonates in coastal plain successions are suggestive of seasonal, semiarid climatic conditions during highstand progradation. Leached paleosols and coals that underlie sequence boundaries and occur within estuarine fills are suggestive of humid conditions during late highstand through early transgression. This pattern may reflect fluctuations in monsoonal circulation whereby the latitudinal shift of seasonal moisture was restricted to the equatorial zone during glaciations. The fourth-order sequences stack into two (2-4 Ma) composite sequences that consist of: 1) a basal retrogradational interval comprised of a major paleovalley-fill sequence overlain by a thick aggradational sequence set made up of fluvial/ coastal plain sequences (TST); 2) a marine interval that demarcates maximum flooding; and 3)(where preserved) a progradational sequence set consisting of minor incised valley-fill sequences (HST). These composite sequences document accommodation change that may reflect global tectono-eustasy. / Ph. D.

<p> Chesterfield Inlet drains an area of 290,000 km^2, between Great Slave Lake and northern Hudson Bay, of predominantly continuous permafrost terrain. The 220-kilometre-long inlet may be used as an important navigation link to Baker Lake and potential pipeline sites. The inlet forms a complex network and is characterized by strong tidal forcing.</p> <p> A one-dimensional numerical model, using a weighted, implicit, finite difference scheme, was modified for application to the network. Sparse matrix techniques were incorporated into the model to speed Gaussian Elimination in the solution of the equations.</p> <p> Tidal constituents, derived from admittance calculations, were used to predict water levels at eight tide gauge locations. Tidal predictions at Sandpiper Island were used as the downstream boundary condition for the numerical model, while tidal predictions at the other gauge locations were used in the model calibration.</p> <p> The observed and model-computed water levels are in good agreement over the lower half of the inlet. Appreciable differences between the observed and computed values were encountered in the upper reaches. Although some of these discrepancies are attributable to errors in the upstream boundary condition and schematization of the model, there is evidence to suggest that time and range errors may exist in some of the recorded tidal data.</p> <p> The variation in the phase and amplitude of the tide throughout the inlet is determined through an examination of the tidal constituents and the model results. Power spectra of the observed and model-predicted water levels reveal that nonlinear interactions of the major tidal constituents take place in the upper portion of the inlet.</p> / Thesis / Master of Engineering (MEngr)

<p> Foraminiferal and thecamoebian biofacies were documented in the modem Korphos marsh located on the western coast of the Saronikos Gulf, Greece in order to define the general ecological features (such as salinity and proximity to marine influence) of the environments they occupied. These constraints were later used to identify fossil biofacies in subsurface marsh sediments at Korphos. </p> <p> Positive marine tendencies identified in fossil biofacies distributions were used for the first time to radiocarbon date relative changes in sea-level implied by a series of discrete, submerged tidal notches and beach rock adjacent to the marsh along the coast. Magnitude of subsidence events based on notch and beach rock data were measured to 2.9m, 0.5m, 1.3m, 0.39m, 0.47m, and 0.34m. The relatively unaltered v-shape of each notch profile suggested that sea-level rise was rapid and episodic. </p> <p> A comparison between the tidal notches and beach rock and an isostatically corrected model of sea-level for this area isolated the tectonic contribution to sea-level change and revealed that at least four of the six sea-level indicators plotted well-below predicted sea-level during subsidence. Therefore, the gradual sea-level rise of the late Holocene was interrupted by at least four sub-meter to meter-scale, step-wise increases in relative sea-level during coseismic subsidence of the Korphos marsh. The results of this study show how the combination of geomorphological and salt-marsh records have the potential to remove errors stemming from a lack of datable material for notches and autocompaction of marsh sediments when reconstructing local sea-level change. </p> / Thesis / Master of Science (MSc)

Tidal energy is a clean, sustainable, reliable, predictable source of energy. Recent developments in underwater turbines have made harvesting tidal energy feasible. Determining the power potential available in a given water body can be accomplished by using numerical hydraulic models to predict the flow velocity at a location of interest. The East River in Manhattan has been used here in an effort to develop a modeling methodology for assessing the power potential of a site. Two two-dimensional CFD models, FESWMS and TUFLOW, as well as one one-dimensional model, HEC-RAS, are used to analyze flows in the East River. Comparisons are made between the models and TUFLOW proves to best represent flows in the East River. HEC-RAS provides accurate results; however, the one-dimensional results lack the necessary detail of a two-dimensional model. FESWMS cannot produce results that mimic actual flow conditions in the East River. Using the TUFLOW model, power and energy estimates are made. These estimates show that a two-dimensional model, such as TUFLOW, can be a great tool for engineers and planners developing tidal energy projects. Using the results of this work, a methodology is developed to assess power potential at other sites using publicly available data. / Master of Science

The Virginia Department of Environmental Quality (VADEQ) under the direction of the United States Environmental Protection Agency (USEPA) has listed the lower Appomattox River as impaired because it violates current water quality standards for fecal coliforms. To advance the analytical process by which various scenarios for improving water quality within the estuary are examined, an array of computer-based hydrodynamic and water quality models were investigated. The Dynamic Estuary Model (DYNHYD5), developed by USEPA, was used to simulate hydrodynamics within the lower Appomattox River. The Water Quality Analysis Simulation Program (WASP6.1), also developed by USEPA, was employed to perform water quality simulations of fecal coliforms. Also, a detailed literature review examined DYNHYD5 and WASP6.1 model theory, computer-based model solution techniques, and background hydrodynamic theory. DYNHYD5 sensitivity analysis showed that the model was most responsive to tidal heights (seaward boundary conditions) both upstream and downstream within the model network. Specific model parameters were varied during calibration until modeled water surface elevations converged on observed water surface elevations. A goodness-of-fit value of 0.749 was determined with linear regression analysis for model calibration. DYNHYD5 input parameter validation was performed with additional observations and a goodness-of-fit value of 0.829 was calculated. Through sensitivity analysis, WASP6.1 proved to be most responsive to coliform loading rates in the downstream direction and boundary concentrations in the upstream direction. With these results, WASP6.1 input parameters were calibrated against observed fecal coliform concentrations. A goodness-of-fit value of 0.573 was determined with linear regression analysis for model calibration. WASP6.1 input parameter validation was performed with additional observations and a goodness-of-fit value of 0.0002 was calculated. Model results suggest that hydrodynamic model calibration and validation can be improved with additional tidal height observations at the downstream seaward boundary. Similarly, water quality model calibration and validation can possibly be improved with the aid of detailed, time-variable coliform concentrations at the downstream seaward boundary. Therefore, it is recommended that a water quality sampling station and tidal stage recorder be installed at the confluence of the Appomattox and James Rivers to provide for further testing of estuary hydrodynamic and water quality models. / Master of Science

In Alabama, the term "coastal shoreline" applies to the Gulf shoreline and the shorelines of estuaries, bays, and sounds connected to the Gulf of Mexico and subject to its tides. However, Alabama shoreline studies have yet to include Little Lagoon, which has been connected to the Gulf of Mexico for most of the last 200 years, according to historical charts. This study used historical nautical charts, aerial photographs, and LIDAR derived shorelines from 1917 to 2004 to analyze shoreline change on Little Lagoon and its adjacent Gulf shoreline. The high water line was used as the common reference feature, and all shorelines were georeferenced, projected, and digitized in a Geographic In-formation System. Between 1917 and 2001, the Gulf shoreline eroded an average of 40 m over 12.7 km, with some transects eroding almost 120 m while others accreted almost 60 m. The greatest changes to the Gulf shoreline were found near natural inlets, downdrift of jetties, and coincident with nourishment projects. Between 1955 and 1997, Little Lagoon shrank 0.5%, or 51.4 km², from 10,285.9 km² to 10,234.5 km². The greatest changes to Little Lagoon were found on its southern shoreline and near inlets, human development, and hurricane overwash fans. A correlation analysis conducted on the Gulf shoreline and Little Lagoon' s southern shoreline indicated that although weak overall correlation values exist when the entire 12.7 km study area is compared, strong correlation values are obtained in some areas when compared over one kilometer sections. The strongest correlations were found in the same locations as the greatest changes. / Master of Science