Academic literature on the topic 'Shoreline change'

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.

Thesis (Ph. D.)--Ohio State University, 2003.<br>Title from first page of PDF file. Document formatted into pages; contains xiv, 142 p.; also includes graphics (some col.). Includes abstract and vita. Advisor: Ronxing Li, Dept.of Civil Engineering and Geodetic Science. Includes bibliographical references (p. 134-142).

This study focuses on the impact of potential changes in the wind-wave climate on shoreline change. The 'one-line' model for medium to long-term prediction of coastline evolution is employed. New analytical and numerical solutions of this important model are described. Specifically: 1) original semi-analytical solutions are derived that relax the unrealistic assumption of existing analytical work that a constant wave condition drives shoreline change and, 2) a more general form of the one-line model is solved with a novel application of the 'Method of Lines'. Model input consists of 30-year nearshore wave climate scenarios, corresponding to the 'present' (1961-1990) and the future (2071-2100). Winds from a high resolution, (12km x 12km), regional climate model, obtained offshore of the south-central coast of England at a dense temporal resolution of 3 hours, are used to develop the aforementioned wave climate scenarios, through hindcast and inshore wave transformation. A hypothetical shoreline segment is adopted as a 'benchmark' case for comparisons. Monthly and seasonal statistics of output shoreline positions are generated and assessedfo r relative changeso f 'significance' between 'present' and future. Different degrees of evidence that such changes do exist are found. This study is the first application of such high resolution climate model output to investigate climate change impact on shoreline response. Major findings include: 1) shoreline changes of 'significance' are strongly linked to 'significant' changes in future wave direction, 2) future changes appear smaller for entire seasons than for individual months, 3) shoreline position variability is often smaller in the future, 4) different climate model experiments produce diverging results; however, general trends are largely similar. The present study, at a fundamental level, offers analytical solutions of the 'oneline' model that are closer to reality and a numerical solution that is of increased effciency. At a practical level, it contributes to better understanding of the patterns of shoreline response to changing offshore wave climate through: 1) the use of fast and straightforward methods that can accommodate numerous climate scenarios without need for data reduction, and 2) the development of a methodology for using climate model output for coastal climate change impact assessment studies.

Thesis (M.S.)--East Carolina University, 2009.<br>Presented to the faculty of the Department of Geological Sciences. Advisor: D. Reide Corbett. Title from PDF t.p. (viewed May 3, 2010). Includes bibliographical references.

Dissertation (Ph.D. in Physical Oceanography)--Naval Postgraduate School, June 2010.<br>Dissertation supervisor: Thornton, Edward B. "June 2010." Description based on title screen as viewed on July 16, 2010. Author(s) subject terms: Rip channels, megacusps, alongshore sediment transport, morphodynamics, XBeach, surf-zone video, correlations, infragravity, VLF. Includes bibliographical references (p. 103-108). Also available in print.

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.<br>Master of Science

In this study, available coastal models are briefly discussed and under wind waves and a numerical shoreline change model for longshore sediment transport based on &ldquo<br>one-line&rdquo<br>theory is developed. In numerical model, wave diffraction phenomenon in one-dimensional modeling is extensively discussed and to represent the irregular wave diffraction in the sheltered zones of coastal structures a simpler approach based on the methodology introduced by Kamphuis (2000) is proposed. Furthermore, the numerical model results are compared with analytical solutions of accretion and erosion at a single groin. An application to a case study of a groin field constructed to the east side of Kizilirmak river mouth, at Bafra alluvial plain, is carried out by the numerical model. The results of comparisons show that the numerical model is in good agreement with the analytical solutions of shoreline changes at a groin. Similarly, numerical model results are compared with field data of Bafra and it is shown that they are in good agreement qualitatively. Therefore, the numerical model is accepted to be capable of representing of shoreline evolution qualitatively even for complex coastal regions.

Despite evidence of the geologic and morphologic complexity of inner shelves worldwide, there is a paucity of observations from the nearshore, inhibiting direct comparison of these factors to coastal change. Using geophysical instruments to characterize the geology of the nearshore, this research focuses on the relationships between nearshore stratigraphy, sediment heterogeneity, shoreface morphology and shoreline behavior. While generally not considered in engineering models of shoreline evolution, these factors influence nearshore processes. Overall, the findings presented highlight the importance of nearshore geology, both at the seafloor and underlying it, in contributing to modem sediment transport processes affecting beaches. Shallow, sub-seafloor geology limits the availability of nearshore sediment available for exchange with the shoreline and is correlated to shoreline change occurring over time scales related to coastal sediment resource management (decades). Shore-oblique sandbars are related to higher volumetric variability in the nearshore and on the beach, whereas traditional shore-parallel sandbars are not. Shorelines adjacent to shore-oblique bars respond to hurricanes and nor'easters differently than other regions of shoreline, helping to explain some spatial variability in patterns of shoreline erosion and accretion. Finally, the geologic framework underlying the seafloor is a source of mixed sediments to the modern coastal system. This contribution has implications for the formation and preservation of specific inner shelf morphologies associated with varied sediments. These results further our knowledge of the geologic variability inherent to sandy coastlines and challenge coastal scientists and engineers to represent this natural variability in predictive models of shoreline change to better predict coastal response to rising sea level and storms.

The efficacy of coastal development regulations in North Carolina is dependent on accurately calculated shoreline erosion rates. North Carolina?s current methodology for regulatory erosion rate calculation does not take advantage of emerging GIS, photogrammetric, and engineering technologies. Traditionally, historical shoreline positions from a database created in the 1970s have been coupled with a modern shoreline position to calculate erosion rates. The photos from which these historical shorelines come were subject to errors of tilt, variable scale, lens distortion, and relief displacement. Most of these errors could be removed using modern photogrammetric methods. In this study, an effort was made to acquire and rectify, using digital image processing, prints of the original historical photography for Bodie Island, North Carolina. The photography was rectified using the latest available desktop photogrammetry technology. Digitized shorelines were then compared to shorelines of similar date created without the benefit of this modern technology. Uncertainty associated with shoreline positions was documented throughout the process. It was found that the newly created shorelines were significantly different than their counterparts created with analog means. Many factors caused this difference, including: choice of basemaps, number of tie points between photos, quality of ground control points, method of photo correction, and shoreline delineation technique. Using both linear regression and the endpoint method, a number of erosion rates were calculated with the available shorelines. Despite the differences in position of shorelines of the same date, some of the calculated erosion rates were not significantly different. Specifically, the rate found using all available shorelines prior to this study was very similar to the rate found using all shorelines created in this study. As a result of this and other factors, it was concluded that a complete reproduction of North Carolina?s historical shoreline database may not be warranted. The new rectification procedure does have obvious value, and should be utilized in those locations where there is no existing historical data, or where existing data is thought to be of poor quality. This would especially be the case near inlets or other historically unpopulated areas.