Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Earth and Planetary Sciences, 1978. / Microfiche copy available in Archives and Science. / Bibliography: leaves 104-111. / by Nathan Hawley. / Ph.D.

Thesis (Sc. D.)--Joint Program in Oceanography (Massachusetts Institute of Technology, Dept. of Earth and Planetary Sciences and the Dept. of Meteorology; and the Woods Hole Oceanographic Institution), 1979. / Vita. Also issued in leaves. / Includes bibliographical references (p. [191]-197). / Concern with the impact of human activities on the coastal region of the world's oceans has elicited interest in the so-called "coastal boundary layer"-that band of water adjacent to the coast where ocean currents adjust to the presence of a boundary. Within this zone, roughly 10 km wide, several physical processes appear to be important. One of these, the tides, is of particular interest because their deterministic nature allows unusually thorough analysis from short time series, and because they tend to obscure the other processes. The Coastal Boundary Layer Transect (COBOLT) experiment was conducted within 12 km of the south shore of Long Island, New York to elucidate the characteristics of the coastal boundary layer in the Middle Atlantic Bight. Analysis of data from this experiment shows that 35% of the kinetic energy of currents averaged over the 30 m depth are due to the semidiurnal and diurnal tides. The tidal ellipses, show considerable vertical structure. Near-surface tidal ellipses rotate in the clockwise direction for semidiurnal and diurnal tides, while near-bottom ellipses rotate in the counterclockwise direction for the semidiurnal tide. The angle between the major axis of the ellipse and the local coastline decreases downward for semidiurnal and increases downward for diurnal tides. The major axis of the tidal ellipse formed from the depth averaged semidiurnal currents is not parallel to the local shoreline but is oriented at an angle of -15 degrees. This orientation "tilt" is a consequence of the onshore flux of energy which is computed to be about 800 watts/m. A constant eddy viscosity model with a slippery bottom boundary condition reproduces the main features observed in the vertical structure of both semidiurnal and diurnal tidal ellipses. Another model employing long, rotational, gravity waves (Sverdrup waves) and an absorbing coastline explains the ellipse orientations and onshore energy flux as a consequence of energy dissipation in shallow water. Finally, an analytical model with realistic topography suggests that tidal dissipation may occur very close (2-3 km) to the shore. Internal tidal oscillations primarily occur at diurnal frequencies in the COBOLT data. Analysis suggests that this energy may be Doppler-shifted to higher frequencies by the mean currents of the coastal region. These motions are trapped to the shore and are almost exclusively first baroclinic mode internal waves. / by Paul W. May. / Sc.D.

Yes / Field measurements and numerical simulations demonstrate the existence of an upper saline plume in tidally dominated beaches. The effect of tides on the saltwater-freshwater mixing occurring at both the upper saline plume and lower salt wedge is well understood. However, it is poorly understood whether the tidal driven force acts equally on the mixing behaviours of above two regions and what factors control the mixing fluctuation features. In this study, variable-density, saturated-unsaturated, transient groundwater flow and solute transport numerical models are proposed and performed for saltwater-freshwater mixing subject to tidal forcing on a sloping beach. A range of tidal amplitude, fresh groundwater flux, hydraulic conductivity, beach slope and dispersivity anisotropy are simulated. Based on time sequential salinity data, the gross mixing features are quantified by computing the spatial moments in three different aspects, namely, the centre point, length and width, and the volume (or area in a two-dimensional case). Simulated salinity distribution varies significantly at saltwater-freshwater interfaces. Mixing characteristics of the upper saline plume greatly differ from those in the salt wedge for both the transient and quasi-steady state. The mixing of the upper saline plume largely inherits the fluctuation characteristics of the sea tide in both the transverse and longitudinal directions when the quasi-steady state is reached. On the other hand, the mixing in the salt wedge is relatively steady and shows little fluctuation. The normalized mixing width and length, mixing volume and the fluctuation amplitude of the mass centre in the upper saline plume are, in general, one-magnitude-order larger than those in the salt wedge region. In the longitudinal direction, tidal amplitude, fresh groundwater flux, hydraulic conductivity and beach slope are significant control factors of fluctuation amplitude. In the transverse direction, tidal amplitude and beach slope are the main control parameters. Very small dispersivity anisotropy (e.g., α_L⁄α_T <5) could greatly suppress mixing fluctuation in the longitudinal direction. This work underlines the close connection between the sea tides and the upper saline plume in the aspect of mixing, thereby enhancing understanding of the interplay between tidal oscillations and mixing mechanisms in tidally dominated sloping beach systems. / Shenzhen Key Laboratory for Coastal Ocean Dynamics and Environment (No. ZDSY20130402163735964), National High Technology Research & Development Program of China (No. 2012AA09A409).

Yes / A two-dimensional model based on OpenTidalFarm is applied to simulate tidal stream flow around turbines. The model is governed by shallow water equations and is able to optimize the layout of the deployed turbine array in terms of maximizing the energy outputs. Three turbine array layouts including two structured layouts (regular and staggered) and one unstructured layout (optimized) are simulated to investigate the effect of turbine layouts on energy extraction. The present study shows that more energy could be extracted when lateral spacing decreases and longitudinal spacing increases within the same domain, namely the effective turbine layout is to deploy more turbines in the first row to extract energy from undisturbed tidal stream, while larger longitudinal spacing will make it possible for tidal stream to recover more before reaching the next turbines row. Taking the tidal stream turbines array around Zhoushan Islands as a case study, results show that the optimized layout can extract 106.8% energy of that extracted by the regular and staggered layout for a full tide in the same marine area. Additionally, the turbine array has a great influence on tidal stream velocities immediately behind the array and has little effect on far-field wake flow. / National Natural Science Foundation Council of China (51879098), and the Marine Renewable Energy Research Project of State Oceanic Administration (GHME2015GC01).

Yes / In nearshore regions, bidirectional tidal flow is the main hydrodynamic factor, which induces local scour around submarine pipelines. So far, most studies on scour around submarine pipelines only consider the action of unidirectional, steady currents and little attention has been paid to the situation of bidirectional tidal currents. To deeply understand scour characteristics and produce a more accurate prediction method in bidirectional tidal currents for engineering application, a series of laboratory scale experiments were conducted in a bidirectional current flume. The experiments were carried out at a length scale of 1:20 and the tidal currents were scaled with field measurements from Cezhen pipeline in Hangzhou Bay, China. The experimental results showed that under bidirectional tidal currents, the scour depth increased significantly during the first half of the tidal cycle and it only increased slightly when the flow of the tidal velocity was near maximum flood or ebb in the following tidal cycle. Compared with scour under a unidirectional steady current, the scour profile under a bidirectional tidal current was more symmetrical, and the scour depth in a bidirectional tidal current was on average 80% of that under a unidirectional, steady current based on maximum peak velocity. Based on previous research and the present experimental data, a more accurate fitted equation to predict the tidally induced live-bed scour depth around submarine pipelines was proposed and has been verified using field data from the Cezhen pipeline.

The objective of this thesis is to determine the effectiveness of Federal, state and local government interactions in administration of tidal wetland protection measures in Virginia. Federal protection for wetlands is authorized by the Clean Water Act [33 U.S.C.A. 1251 et seq. (1986), as amended (Supp. 1987)] and the Rivers and Harbors Act [33 U.S.C.A. 401 et seq. (1986), as amended (Supp. 1987)]. State and local authority is provided by the Virginia Wetlands Act [Va.Code Ann., sec. 62.1-13.1 et seq. (1987)]. Because of overlapping jurisdictions of the statutes, Federal, state, and local governments must interact while implementing wetland protection programs. Effective interactions between the various levels of government are important for the preservation and protection of tidal wetlands. If the three levels of government are able to efficiently administer a program that provides adequate protection of wetlands, similar programs may be applied in other areas such as non-point source pollution control. A history of the development of the wetlands protection program is presented along with a description of applicable statutes, regulations, and permitting requirements. Included is an analysis of the implementation of the wetland statutes by case studies of program operations, a comparison of decisions on applications made by the three different government agencies, and identification of impacts and future trends of the wetland protection programs. / Master of Science

京都大学 / 新制・論文博士 / 博士(工学) / 乙第13491号 / 論工博第4200号 / 新制||工||1785(附属図書館) / (主査)教授 角 哲也, 准教授 Kantoush Sameh, 准教授 竹門 康弘 / 学位規則第4条第2項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

Background: Adolescents in need of care that cannot be provided by Child and Adolescent Psychiatry, or by other aid provided by the Social service can be placed and cared for at the youth facilities of the Swedish National Board of Institutional Care (SiS). Adolescents being cared for at the youth facilities of SiS have complex needs of care, including both psychiatric conditions and psychosocial issues. At every institution at least one nurse with responsibility of the adolescents' care is employed. There is a lack of research on how these nurses experience the care which they provide at the youth facilities. Purpose: The aim of the study was to describe the experiences of the nurses caring for adolescents in the SiS. Method: A qualitative interview study was conducted. Eight nurses employed by the SiS were interviewed. The data was then analyzed according to Lundberg and Graneheim's model for qualitative content analysis. Results: The results are presented in three main themes and nine subthemes: Challenges and opportunities with working within SiS. Lack of collaboration and information, resources and competence and the work environment within SiS. The role of the nurse. Experience of working under different laws and assuming different work roles, leading and training other staff. Meeting the care needs of adolescents. To be able to see the entire adolescent, create an alliance and educate the youth about their own health. Conclusion: The nurses experienced an inexplicit health care assignment within SiS. They experienced a lack of health care competence among the staff working at the wards. A better collaboration with other health care departments, such as Child and Adolescent Psychiatry and primary care centers, was considered desirable. The adolescents are considered to present with great suffering and complexcare needs, and their psychiatric needs are considered the most difficult to meet. The nurses need to create an alliance with the adolescents, and to see the individual beyond criminal history, diagnosis and social issues. This essay contributes to the visibility of the nurses' perspective and of how they can contribute to the development of health care within the institutions, but more studies and more extensive research on the subject are sorely needed.

Tidal marsh and its bird community across the northern Gulf of Mexico are subject to numerous disturbances such as oil spills, hurricanes, habitat loss from land use change, and high relative sea level rise rates looming in the future. Baseline population data and landscape associations are greatly needed to assess the current distribution and the future impact of perturbations on marsh birds across the Mississippi Gulf Coast. Using a standardized sampling design and point count survey protocol, we determined the abundance and population size of Clapper Rails, Common/Purple Gallinules, Least Bitterns, Marsh Wrens, Seaside Sparrows, Red-winged Blackbirds, and Common Yellowthroats across the Mississippi Gulf Coast. With abundance models for each species in 2021 and 2022, we further investigated the impact of important fine and broad scale landscape variables that affected species-specific abundance across variable marsh complexes. Finally, we generated species distribution maps based on our spatially-explicit baseline population estimates.

Sedimentary characteristics of grainy non-skeletal tidal flats along windward platform margins have not been described in modern environments and may be misidentified or misclassified in the rock record. This study describes the sedimentology of such an environment to aid in accurate identification and characterization in the ancient. At Shroud Cay, a grain-dominated tidal flat is sheltered from the high energy of the shelf by a ring of cemented Pleistocene and partly indurated Holocene eolianite islands separated by several narrow tidal passes. Depositional texture, environment of deposition and geobody mapping, extensive sediment sampling, and vibracoring have shown that, though the cemented island provide a barrier from the high energy of the shelf, a high degree of tidal energy still occurs behind this barrier as indicated by the overwhelmingly grainy nature of all of the tidal flat sub-environments. Intertidal flats comprise the majority of the tidal flat surface. These flats are characterized by patchy Scytonema mats overlying bioturbated peloid-ooid grainstones to packstones with cemented lithoclasts. Three main tidal channels dissect the tidal flat and allow diurnal flow, one of those tidal channels does not exit the tidal flat but dead-ends behind a cemented Holocene beach dune ridge along the eastern side of Shroud Cay. Peloid-ooid-skeletal grainstone tidal bars and peloid-ooid packstones fill much of the channels. Most of the channels are bordered by low-relief grain-rich packstone levees often capped by red mangroves and algal mats. The interior-most supratidal parts of the flat, often in the lee of the windward Holocene ridge, are covered by a thick (5-~25cm) Scytonema microbial mat underlain by grain-rich ooid-peloid packstones. Ancient grain-dominated carbonate tidal flats and eolianite deposits like Shroud Cay?s are the reservoir rocks in some of today?s largest hydrocarbon fields. We develop a model for the evolution of the grain-dominated tidal flat, document and compare differences between the grain-rich tidal flat and surrounding environments of deposition, and develop a set of criteria for recognition. These criteria can be used to more accurately characterize reservoirs such as the Jurassic Smackover fields, to avoid mis-classification of similar settings, and more effectively produce those reservoirs.