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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
21

Proeven over den invloed van golven op een strand in verband met enkele waarnemingen aan de nederlandsche kust ...

Timmermans, Pieter Dirk. January 1900 (has links)
Proefschrift--Leyden. "Literatuurlijst": p. 155-156. / Pages 5-156 have also continuous paging, 235-386. Summary in English.
22

Nearshore currents over a barred beach

Faria, Antonio Fernando Garcez. January 1997 (has links)
Thesis (Ph. D.)--Naval Postgraduate School, 1997. / Includes bibliographical references: (p. 149-152).
23

Spatial patterns in beach morphology and sedimentology in the Apostle Islands, northern Wisconsin

Engstrom, Wayne N. January 1972 (has links)
Thesis (Ph. D.)--University of Wisconsin--Madison, 1972. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.
24

Hazardous Beach-System Development in Maine and Some Outcomes of the Sand Dune Rules

Knisel, Julia M. January 2003 (has links) (PDF)
No description available.
25

Field measurements and modeling of surfzone currents on inhomogeneous beaches

Brown, Jennifer. January 2009 (has links)
Thesis (M.C.E.)--University of Delaware, 2009. / Principal faculty advisors: Jamie H. MacMahan and James T. Kirby, Dept. of Civil & Environmental Engineering. Includes bibliographical references.
26

An experimental and numerical study of surface-subsurface interaction for bore-driven swash on coarse-grained beaches

Steenhauer, Kate January 2010 (has links)
Particle Image Velocimetry, Laser Induced Fluorescence, pressure transducers and wetting front digital image measurements were made for two steep immobile beaches with different roughness and permeability (1.5mm and 10mm sediment).  The experimental results proved valuable in revealing the interaction mechanisms between the swash and the subsurface flow, in particular, showing the significant role of entrapped air.  The comprehensive dataset was used for the development and validation of a numerical model of swash consisting of a surface and subsurface flow model. The surface flow model, capable of simulating the movement of a steep bore over a permeable coarse-grained beach, is based on the non-linear shallow water equations solved using the Godunov-type finite volume ADER scheme.  The subsurface flow model simulates the vertical movements of the wetting front and the horizontal movement of air and groundwater within a beach.  Vertical movement is simulated as downwards or upwards piston-like flow, with the drag term parameterised by the Forchheimer equation.  Air and groundwater flow are simulated using simple Darcian modules. The experimental and numerical results reveal the distinctly different behaviour of filtration and pressure within the beach for the two types of sediment.  The considerable build-up of air pressure, induced by entrapped air below the wetting front in the unsaturated region of the 1.5mm sediment, minimise the loss of surface water to the beach by reducing infiltration rates.  Moreover it causes the flow within the bed to reverse and induce exfiltration.  Conversely, the build-up of air pressure in the 10mm beach is considerably lower, resulting in higher infiltration rates and a greater exchange of water from surface flow to the subsurface.
27

Using acoustic backscatter to measure sediment flux in the surf zone

Roland, Preston J. 12 1900 (has links)
Transport of sediment in coastal regions directly impacts mine countermeasure operations and naval construction efforts. Wave induced shear stress in the surf zone is responsible for entraining sediment particles into suspension within the combined wave and current boundary layer, where momentum is imparted through highly nonlinear processes. Therefore, a detailed understanding of sediment flux processes in the surf zone is essential to accurately model net sediment transport. This study examines the use of acoustic backscatter inversion as a means of measuring sediment concentration profiles. Measurements of sediment concentration and velocity profiles were made by a high frequency Doppler velocity profiler deployed on Blackâ s Beach during the Nearshore Canyon Experiment, NCEX. Profiles of sediment flux were compared with hourly mean current measurements from a cross-shore/long-shore array of PUV sensors and two-dimensional planner images of the morphological evolution provided by a three camera Argus video suite. Observations from a seven day period containing the development and evolution of a weak rip channel demonstrated that acoustic backscatter inversion techniques, when calibrated with in situ sediment samples, provide high spatial and temporal resolution estimates of sediment concentration and fluxes into the thin wave boundary layer. These sediment transport measurements were correlated with observed mean currents and rip channel evolution, and show a strong morphological response to the sediment flux.
28

Rip channel migration in the nearshore

Minetree, Courtney M. 09 1900 (has links)
Video imaging data generated from the Naval Postgraduate School Imaging System (NAPSIS) during November 2004 to June 2006 was analyzed to determine the location of rip channels and track their morphology. During the study period, the rip fields constantly changed in shape, size, and location. Rip channels were found to have a mean migration southward at a rate of 0.16 meters per day with a standard deviation of 7.6 meters per day and maximum rates varying between approximately 30 meters per day north and 30 meters per day south. The migration exhibited a strong seasonal variation with southerly shifts in the fall and winter months, northerly shifts in the late winter and early spring months, and no significant shift in the late spring and summer months. Directional wave spectra measured every hour at the offshore NOAA buoy were refracted to the 10 meter depth contour at Marina and Sand City and compared with measured spectra at these locations. The significant wave heights at both locations exhibited a correlation of 0.94. Mean wave directions for Marina and Sand City were found to have correlations of 0.83 and 0.34, respectively. These refracted data were then used to calculate sediment transport rates at Stillwell Hall, Fort Ord. Rip channel migration and calculated sediment transport rates were correlated at 0.8, qualitatively confirming the hypothesis that the migration rate of rip channels is a function of modeled alongshore sediment transport. The sometimes rapid migration of these large scale morphological features is critical to the successful planning and execution of U.S. Navy and Marine Corps beach assaults and the operation of mine warfare. Because amphibious and special forces operate mainly in shallow areas, the modeling of rip current direction and magnitude contributes greatly to effective mission organization and accomplishment. In addition to causing mines to drift, rip currents transport sediment that can cause the underlying morphology to change, possibly covering bottom mines and creating a potential hazard for military forces operating in the area. Being able to predict where mines may be drifting and how much sediment has concealed them is a necessity in securing a littoral battlespace.
29

Sustainable Ecological and Recreational Management of Sandy Beach Systems

January 1994 (has links)
Sandy beaches are a primary focus of recreational and other pressures from growing coastal populations, and are major natural and economic assets for national and international tourism, but have not received adequate research attention prior to this study. Although the limited ecological research to date indicates that the nearshore volumes of sandy beach systems may be as biologically productive as estuaries and wetlands, the management of sandy beaches has not been based on ecological or sustainability principles. In this study, the principles and goals of ecologically sustainable development (ESD) are applied in investigations designed to develop improved ecological and recreational management of metropolitan sandy beach ecosystems, whereby ecological functions are maintained simultaneously with recreational and related uses. The conventional view that sandy beaches are resilient to recreational use, and are more likely to be seriously impacted by other forms of human activity, seems to have precluded serious research investigation of questions such as: what are the responses of both beach biota and human users to environmental variables influencing the system; what are the simultaneous levels, distributions and diversity of beach biota in relation to levels, distributions and categories of beach users; and what ecological impacts are likely from human beach use on biota at points of interaction, temporally and spatially? From the first section of the project, it has been shown that our present understanding of the functions, processes and responses to human disturbances of sandy beach ecosystems is extremely poor, compared with that of rock platforms. New methodologies have been developed in the current study for experimental investigations into aspects of sandy beach ecology and recreational use which have never previously been considered. Relationships between environmental variables and categories of beach use have been quantified, and show promise for use in predictive modelling to guide management. Current approaches to the management of sandy beaches and beach recreation, as aspects of environmental and coastal resource management, were then critically examined. The structures, functions and decision-making procedures of the major spheres of government, and their management agencies, were evaluated and found to provide inherent obstacles to effective ecological and recreational management of ecosystems. Coastal resource and beach management by public agencies were assessed for Durban and Sydney. Comparative analysis has provided information that can be used to develop guidelines for integrated ecologial and recreational management of sandy beach systems. In a synthesis of all of the above findings, a new procedural model has been constructed, for sustainable ecological and recreational management of sandy beach systems. This model is proposed as a framework for future integrated coastal resource research and management. Note: Three published papers have been produced from the research in this study, and have been presented at conferences, being Sinclair-Hannocks and Keane (1992) at the Sydney Sister City Environmental Summit; Sinclair-Hannocks (1993) at the World Leisure and Recreation Association Congress; and Tsang and Sinclair-Hannocks (1993) at the Local Government and Environment Conference.
30

A new conductivity sediment concentration profiler (CCP) for the measurement of nearbed sediment concentrations application in the swash zone on a laboratory beach /

Faries, Joseph W.C. January 2009 (has links)
Thesis (M.C.E.)--University of Delaware, 2009. / Principal faculty advisor: Jack A. Puleo, Dept. of Civil & Environmental Engineer. Includes bibliographical references.

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