Shoreline erosion is an issue of economic and environmental concern on the Texas coast. Texas State Highway 87, located in Jefferson County, Texas, has been repeatedly destroyed by storms and rebuilt in the past 50 years. Reconstruction of State Highway 87 cannot be successfully achieved without an exact assessment of shoreline erosion. This report describes a shoreline assessment to obtain a comprehensive data set that will be used to define the coastal erosion problem and assist in the reconstruction of the roadway. Eight field surveys were conducted that included offshore survey and beach survey (beach profiles). The offshore system utilizes a Real-Time Kinematic Differential Global Positioning System (RTK-DGPS) mounted on a personal watercraft and integrated with a survey quality echo sounder. The beach survey utilizes RTK-DGPS equipment carried by the surveyor in a backpack. The system is an accurate, mobile and efficient method to obtain beach profiles. The two surveys (beach and offshore surveys) are combined to provide a complete beach profile. Data gathered from beach profile surveys enabled the calculation of sediment erosion or accretion rate and direction.

This thesis utilises a range of methodologies to investigate the historical shoreline change and beach morphodynamics at Rapahoe Bay, West Coast, New Zealand. Rapahoe Bay is a small embayment located 15 km north of Greymouth, and contains a complex and dynamic environment under a dominant swell condition. The objectives of this thesis include the investigation the coastline history through aerial photographs and relevant literature, identify and quantify historical shoreline change and the processes that have induced change, examine the short term and seasonal changes in beach profile, identify and quantify wave and transport process and to test the applicability of the zeta shoreline curve on a composite beach. This combined approach investigates the dynamics and process drivers involved in coastline change. This thesis contributes to the research gap of understanding morphodynamic behaviour and controls of composite beach under a dominant swell. Composite beaches types are a variation from mixed sand and gravel beaches with distinct morphological differences. This thesis provides an insight in to the morphodynamic behaviour of composite beaches. The study area contains a small village based by the shoreline and the potential coastal hazard that threatens people, property and infrastructure. Therefore the results from this thesis have an important management implication towards mitigating coastal hazards. The historical coastline change was induced through a combination of wave processes and transport, composite beach morphodynamic behaviour, anthropogenic influence and planform shape. Results show that human infrastructure restricted the retreat of a small hapua landward of the gravel barrier. A combination of change in sediment supply, consistent sediment transport and a high wave energy environment resulted in rapid landward retreat through gravel rollover and coastal erosion. The gravel barrier morphodynamics include increase in crest elevation, steeper shore gradients as a response to high swells resulting in erosion or rollover. The wave environment includes a sediment transport hinge point due to a dominant wave refraction and changes in the shoreline orientation, which further induces coastal erosion. The valid applicability of the zeta planform shape concludes that the shoreline may further iii retreat due to geological controls, potential sediment transport and the transgressive nature of the composite beaches. The combination of methods and results provide both quantified historical change and also potential future scenarios of coastline reshaping. These methods and results are applicable not only to Rapahoe but along other West Coast composite beaches, and the validity of the combination of methods provides a greater understanding of the behaviour of morphodynamic composite beaches and provides quantified results of historical shoreline change and sediment transport at the field site.

ABSTRACT Most sandy beaches around the world have been under the threat of being eroded in the past six decades, resulting in shoreline retreat; thus, calling for various shoreline protection devices to be constructed to preserve the well-being of coastal habitants. To achieve this purpose, research on shoreline changes and development of numerical or mathematical models for predicting shoreline changes would help attain the goal of sustainable use of coastal land. This thesis reports preliminary engineering applications of GENESIS that have become a popular tool for modeling long-term shoreline changes. The aim of this study is to predict the potential shoreline change in the light of different layouts of shoreline protection devices. The topics addressed in this report include the discussion on the parameters in GENESIS; shoreline changes in the lee and/or on the back of single groin and single detached breakwater with normal or oblique wave incidence; comparison on the efficiency of beach accretion as a function of gap width between structures and the sequence of their construction, as well as assessment on the restraint from the two different boundary conditions used in GENESIS. The results of modeling using GENESIS are then verified using the result based on the empirical parabolic bay shape equation and a physical scale model, in order to test the feasibility of applying GENESIS for practical engineering uses. From the results of this study, it can be stated that GENESIS is valuable reference tool for engineering design, despite some shortcomings in setting up boundary conditions and the invariant nature of and values which do not respond to the process of changing shoreline curvature. However, the GENESIS system would have a positive contribution to the modeling of shoreline changes upon the construction of protective devices on a coast.

This thesis utilises a range of methodologies to investigate the historical shoreline change and beach morphodynamics at Rapahoe Bay, West Coast, New Zealand. Rapahoe Bay is a small embayment located 15 km north of Greymouth, and contains a complex and dynamic environment under a dominant swell condition. The objectives of this thesis include the investigation the coastline history through aerial photographs and relevant literature, identify and quantify historical shoreline change and the processes that have induced change, examine the short term and seasonal changes in beach profile, identify and quantify wave and transport process and to test the applicability of the zeta shoreline curve on a composite beach. This combined approach investigates the dynamics and process drivers involved in coastline change. This thesis contributes to the research gap of understanding morphodynamic behaviour and controls of composite beach under a dominant swell. Composite beaches types are a variation from mixed sand and gravel beaches with distinct morphological differences. This thesis provides an insight in to the morphodynamic behaviour of composite beaches. The study area contains a small village based by the shoreline and the potential coastal hazard that threatens people, property and infrastructure. Therefore the results from this thesis have an important management implication towards mitigating coastal hazards. The historical coastline change was induced through a combination of wave processes and transport, composite beach morphodynamic behaviour, anthropogenic influence and planform shape. Results show that human infrastructure restricted the retreat of a small hapua landward of the gravel barrier. A combination of change in sediment supply, consistent sediment transport and a high wave energy environment resulted in rapid landward retreat through gravel rollover and coastal erosion. The gravel barrier morphodynamics include increase in crest elevation, steeper shore gradients as a response to high swells resulting in erosion or rollover. The wave environment includes a sediment transport hinge point due to a dominant wave refraction and changes in the shoreline orientation, which further induces coastal erosion. The valid applicability of the zeta planform shape concludes that the shoreline may further iii retreat due to geological controls, potential sediment transport and the transgressive nature of the composite beaches. The combination of methods and results provide both quantified historical change and also potential future scenarios of coastline reshaping. These methods and results are applicable not only to Rapahoe but along other West Coast composite beaches, and the validity of the combination of methods provides a greater understanding of the behaviour of morphodynamic composite beaches and provides quantified results of historical shoreline change and sediment transport at the field site.

The purpose of this study was to evaluate the local and regional processes causing the shoreline recession of an eroding beach/berm/wetland system on the eastern shore of Mobile Bay. The analysis was then used to evaluate different technologies which could meld to create a holistic shoreline protection design to fortify the entire spectrum of the shoreline. Wind waves are the major erosional force causing a bi-directional, but southerly dominated, longshore transport and an erosional cross-shore transport during large wave events. Erosion mitigation technologies which promote ecological integrity are presented and include: oyster shell breakwaters, SAV establishment, intertidal grass plantings, and tree and shrub plantings. By combining these technologies, a plan which mitigates erosion as well as greatly increases the health of the local ecosystem can be formed. By fortifying in this manner the shoreline and its communities can be more resilient and prepared for future climatological changes and conditions.

No description available.

A controlled laboratory experiment was undertaken to simulate varying swash zone characteristics and sensor-target geometry found in digital images collected by ARGUS coastal imaging systems. Using a hyperspectral sensor, reflectance data were integrated over the respective red, blue and green wavelengths corresponding to a standard ARGUS video imaging sensor. The dominant swash zone parameters affecting shoreline detection were found to be the presence or absence of surface foam, site-specific sediment characteristics (especially colour), and water depth. Winter versus summer solar elevation and the sensor zenith were also found to affect the cross-shore location of the detected waterline. With this new information, site- and time-specific corrections can be applied to coastal digital imagery, to improve the confidence of shoreline detection.

No description available.

A controlled laboratory experiment was undertaken to simulate varying swash zone characteristics and sensor-target geometry found in digital images collected by ARGUS coastal imaging systems. Using a hyperspectral sensor, reflectance data were integrated over the respective red, blue and green wavelengths corresponding to a standard ARGUS video imaging sensor. The dominant swash zone parameters affecting shoreline detection were found to be the presence or absence of surface foam, site-specific sediment characteristics (especially colour), and water depth. Winter versus summer solar elevation and the sensor zenith were also found to affect the cross-shore location of the detected waterline. With this new information, site- and time-specific corrections can be applied to coastal digital imagery, to improve the confidence of shoreline detection.

Title page, table of contents and abstract only. The complete thesis in print form is available from the University of Adelaide Library. / This thesis presents an overview of a 20 year body of research focusing on aspects of the Quaternary coastal evolution of the southern Australian passive continental margin. This work is based on a representative selection of 20 papers chosen from over 90 peer-reviewed articles. One of the principal research foci centres on the application of amino acid racemization (AAR) reactions to the dating of Quaternary coastal sedimentary successions. Based on the degree of racemization of amino acids preserved within the biominerals of fossil molluscs and other marine invertebrates, geochronological frameworks have delineated rates of long-term coastal evolution, relative sea-level changes and neotectonism. The AAR method has been applied to a wide selection of fossil molluscs from sedimentary successions ranging from late Pliocene to latest Holocene age. Holocene coastal successions have been dated using the fast racemizing amino acid, aspartic acid to assign numeric ages to fossils that would otherwise have been problematic to date using the radiocarbon method. The research has provided a novel approach to derive geochronological frameworks to subdivide Quaternary time and is innovative in creating new opportunities to delineate the age of sedimentary successions that could not previously be dated. It has fostered several new avenues of investigative research such as evaluating the taphonomic integrity of sedimentary deposits (time-averaging and spatial fidelity), confidently undertaking stratigraphical correlation and relative age assessments over wide geographical areas, assigning ages to biostratigraphic ally significant fossils (e.g. Anadara trapezia, Marginopora vertebralis), "whole-rock" dating of aeolianites and quantifying rates of coastal evolution and neotectonism. The work has confirmed that southern Australia preserves one of the world's best preserved and most geographically extensive temperate carbonate shoreline successions of last interglacial age (128 to 118 ka). At this time relative sea level was at least 2m above present sea level as shown from peritidal facies on Eyre Peninsula, South Australia. The research has also revealed, based on studies of the last interglacial shoreline that Australia, although a highly stable continent, continues to experience subtle neotectonic movements. These findings have modified the general perception concerning the tectonic stability of the Australian continent, and have reinvigorated an interest in the neotectonic histories of passive continental margins. Differential shoreline elevations of last interglacial deposits relate directly to their pre-Quaternary geotectonic setting and highlight the contrasting stabilities of these geotectonic domains over longer temporal scales. An enhanced understanding of the nature of the stratigraphical record preserved within marginal marine settings, the preservation potential of coastal successions in the longer Quaternary geological record and the spatial and temporal distribution of biostratigraphically significant taxa for the Quaternary represent further outcomes of this body of research. With the exception of the Coorong Coastal Plain in southern South Australia, much of the marginal marine stratigraphical record is dominated by sedimentary successions deposited during the sea level highstands of Marine Isotope Stages 1, 5e and 7, with intertidal facies of late Pleistocene interstadial successions preserved within submarine contexts (e.g. the South Australian Gulfs region and the Lacepede Shelf). The taphonomic integrity of sedimentary deposits has also been investigated based on the degree of racemization within fossils. The research has shown that fossils of broadly similar preservation state may be significantly different in age as attested to by the AAR dating of glacial age lowstand deposits from the outer continental shelf of New South Wales, which has identified strata relating to the last three glacial maxima (Marine Isotope Stages 2, 6 and 8) and has helped to constrain estimates of palaeo sea level in a far-field site for these time intervals. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1384351 / Thesis (D.Sc.) -- University of Adelaide, School of Environmental Sciences, 2009