A multi-decadal survey program undertaken at the Collaroy-Narrabeen embayment in SE Australia identifies medium-term (~2-7 year) cycles of both erosion and accretion across the entire embayment ('beach oscillation') and at its two extremities ('beach rotation'). These cycles have been observed to respond to phase shifts in the El Ni??o/Southern Oscillation (ENSO). To investigate wave and climate controls of embayment variability in finer detail, this study combines historical surveys with 45 years of wave data from the ERA-40 reanalysis and four years of high-resolution beach measurements using RTK-GPS and image-derived survey techniques. ENSO and Southern Annular Mode (SAM) controls of wave variability in the Sydney region are first explored. In general, wave heights increase/decrease and wave directions become more easterly/southerly during La Ni??a/El Ni??o phases. A positive correlation is observed between the SAM and summer wave heights, and a negative correlation between the SAM and winter wave directions. Storm variability is observed to be modified by the ENSO, but not the SAM. In particular, La Ni??a phases are generally associated with longer duration, higher energy events from a more easterly direction when compared to those during El Ni??o phases. Wave controls of embayment variability are subsequently investigated. In the short-term (days - months), beach oscillation/rotation is observed to be the most dominant process, accounting for approx. 60%/20% of overall embayment variability. Beach oscillation is related to changes in wave height and storms, whereas beach rotation is related to changes in wave direction and/or wave period. An empirical model that estimates the beach response to individual storm events is developed. In the longer-term (months - years), beach rotation is observed to respond to both wave heights and directions. Larger waves are sheltered somewhat at the southern end, creating an apparent clockwise rotation under energetic wave conditions. Clockwise/anticlockwise rotations are also observed to follow southerly/easterly wave shifts at lags of up to 12 months. Comparisons between the ENSO and beach oscillation/rotation agree with previous observations that El Ni??o/La Ni??a phases are associated with an overall accretion/erosion and clockwise/anticlockwise rotation of the embayment. In general, the SAM shows little influence on embayment variability. While it is clear that beach oscillation is driven by cross-shore processes, to what extent beach rotation is a longshore and/or cross-shore phenomena requires further investigation.

A multi-decadal survey program undertaken at the Collaroy-Narrabeen embayment in SE Australia identifies medium-term (~2-7 year) cycles of both erosion and accretion across the entire embayment ('beach oscillation') and at its two extremities ('beach rotation'). These cycles have been observed to respond to phase shifts in the El Ni??o/Southern Oscillation (ENSO). To investigate wave and climate controls of embayment variability in finer detail, this study combines historical surveys with 45 years of wave data from the ERA-40 reanalysis and four years of high-resolution beach measurements using RTK-GPS and image-derived survey techniques. ENSO and Southern Annular Mode (SAM) controls of wave variability in the Sydney region are first explored. In general, wave heights increase/decrease and wave directions become more easterly/southerly during La Ni??a/El Ni??o phases. A positive correlation is observed between the SAM and summer wave heights, and a negative correlation between the SAM and winter wave directions. Storm variability is observed to be modified by the ENSO, but not the SAM. In particular, La Ni??a phases are generally associated with longer duration, higher energy events from a more easterly direction when compared to those during El Ni??o phases. Wave controls of embayment variability are subsequently investigated. In the short-term (days - months), beach oscillation/rotation is observed to be the most dominant process, accounting for approx. 60%/20% of overall embayment variability. Beach oscillation is related to changes in wave height and storms, whereas beach rotation is related to changes in wave direction and/or wave period. An empirical model that estimates the beach response to individual storm events is developed. In the longer-term (months - years), beach rotation is observed to respond to both wave heights and directions. Larger waves are sheltered somewhat at the southern end, creating an apparent clockwise rotation under energetic wave conditions. Clockwise/anticlockwise rotations are also observed to follow southerly/easterly wave shifts at lags of up to 12 months. Comparisons between the ENSO and beach oscillation/rotation agree with previous observations that El Ni??o/La Ni??a phases are associated with an overall accretion/erosion and clockwise/anticlockwise rotation of the embayment. In general, the SAM shows little influence on embayment variability. While it is clear that beach oscillation is driven by cross-shore processes, to what extent beach rotation is a longshore and/or cross-shore phenomena requires further investigation.

A multi-decadal survey program undertaken at the Collaroy-Narrabeen embayment in SE Australia identifies medium-term (~2-7 year) cycles of both erosion and accretion across the entire embayment ('beach oscillation') and at its two extremities ('beach rotation'). These cycles have been observed to respond to phase shifts in the El Ni??o/Southern Oscillation (ENSO). To investigate wave and climate controls of embayment variability in finer detail, this study combines historical surveys with 45 years of wave data from the ERA-40 reanalysis and four years of high-resolution beach measurements using RTK-GPS and image-derived survey techniques. ENSO and Southern Annular Mode (SAM) controls of wave variability in the Sydney region are first explored. In general, wave heights increase/decrease and wave directions become more easterly/southerly during La Ni??a/El Ni??o phases. A positive correlation is observed between the SAM and summer wave heights, and a negative correlation between the SAM and winter wave directions. Storm variability is observed to be modified by the ENSO, but not the SAM. In particular, La Ni??a phases are generally associated with longer duration, higher energy events from a more easterly direction when compared to those during El Ni??o phases. Wave controls of embayment variability are subsequently investigated. In the short-term (days - months), beach oscillation/rotation is observed to be the most dominant process, accounting for approx. 60%/20% of overall embayment variability. Beach oscillation is related to changes in wave height and storms, whereas beach rotation is related to changes in wave direction and/or wave period. An empirical model that estimates the beach response to individual storm events is developed. In the longer-term (months - years), beach rotation is observed to respond to both wave heights and directions. Larger waves are sheltered somewhat at the southern end, creating an apparent clockwise rotation under energetic wave conditions. Clockwise/anticlockwise rotations are also observed to follow southerly/easterly wave shifts at lags of up to 12 months. Comparisons between the ENSO and beach oscillation/rotation agree with previous observations that El Ni??o/La Ni??a phases are associated with an overall accretion/erosion and clockwise/anticlockwise rotation of the embayment. In general, the SAM shows little influence on embayment variability. While it is clear that beach oscillation is driven by cross-shore processes, to what extent beach rotation is a longshore and/or cross-shore phenomena requires further investigation.

Wave energy is a major driver for many coastal processes and influences wetland vegetation and shoreline stability. Coastal conservation and restoration projects often include wave climate estimations in the decision-making process for project design. The current method primarily used to estimate a project area's wave climate is the use of wind-wave models. These models use wind speed, wind direction, bathymetry, and fetch to estimate site-specific wave activity. However, these models neglect boat wake which is an important contributor to wave energy in fetch-limited environments. This study used site-specific wave measurements to compare wind-protected and open sites in Back Bay, Mississippi. Study results demonstrated that some protected sites experienced similar or even higher wave activity when compared to the open sites. These findings indicate that excluding boat activity from wave climate estimations could lead to an under-estimation of site-specific wave activity.

Kyoto University (京都大学) / 0048 / 新制・課程博士 / 博士(工学) / 甲第18931号 / 工博第3973号 / 新制||工||1612 / 31882 / 京都大学大学院工学研究科社会基盤工学専攻 / (主査)教授 間瀬 肇, 教授 平石 哲也, 准教授 森 信人 / 学位規則第4条第1項該当

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第18931号 / 工博第3973号 / 新制||工||1612(附属図書館) / 31882 / 京都大学大学院工学研究科社会基盤工学専攻 / (主査)教授 間瀬 肇, 教授 平石 哲也, 准教授 森 信人 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

Coastal restoration has become a necessary and ubiquitous practice to enhance and conserve the many ecosystem services lost by marsh degradation. Wave climate is one of the most critical factors to consider for restoration projects. However, knowledge of the ways that waves affect marsh plants and the ecosystem services they provide is limited. The purpose of my dissertation was to improve the effectiveness of coastal marsh restoration by addressing the limitations and gaps associated with plant and ecosystem responses to waves through empirical research with three primary goals: 1) develop and test a low-cost wave gauge, 2) use it to compare above- and below-ground plant growth responses along a wave climate gradient, and 3) evaluate the effects of waves on nutrient removal in constructed marshes. I used three field and laboratory experiments to accomplish these goals. The low-cost wave gauge was developed using an Arduino microcontroller and various accessories. After development, the gauge was evaluated against a commercial gauge in a series of laboratory and field tests. Comparisons revealed over 90% agreement between the gauges and confirmed the applicability of the low-cost gauge. A total of thirty gauges were then constructed and deployed at sites within Mobile Bay, Alabama and surrounding tributaries. In addition to wave energy, plant data was also collected at each site, including above- and below-ground biomass, shoot density, height, and diameter. These data suggested that waves affect plant growth responses in ways not explained by the current plant response paradigm. For example, while greater diameter shoots best attenuate waves, shoot diameter declined with greater wave exposure in this study. This response was common among the study species. Other plant responses were species-specific. Finally, a field experiment was constructed to examine the main and interactive effects of sediment type, initial planting density, platform slope, and platform position at sites exposed to and protected from waves. Results from this experiment suggested that waves may potentially mitigate the effective removal potential of constructed marshes. Taken together, this dissertation advances research on plant responses to waves and provides new tools for land managers working on coastal restoration and conservation projects.

En esta tesis se propone y desarrolla una completa metodología de calibración de bases de datos de reanálisis de oleaje, en la que se que define el tratamiento de los datos disponibles más adecuado para la información que es necesario caracterizar, particularizado a cada caso concreto de diseño de una obra marítima.En una primera clasificación general se divide en calibraciones puntuales y espaciales. Las metodologías de calibración puntual se utilizan cuando existe información instrumental para calibrar los datos de reanálisis en una posición con un clima marítimo similar, en profundidades indefinidas, al de la localización de la obra en estudio. En cambio, se ha definido una metodología de calibración espacial para calibrar los datos de reanálisis en una zona, a partir de la información instrumental de otras zonas con diferentes climas marítimos al de la localización de la obra en estudio.Todas las metodologías de calibración han sido aplicadas al ámbito costero español, calibrando la base de datos de reanálisis SIMAR-44 (Organismo Público Puertos del Estado) con información instrumental (boyas y satélites). / This thesis proposes and develops a complete calibration methodology of wave hindcast databases, in which it is defined how to right process the available data for the information that it is necessary to characterize, as a function of the individual case of coastal structure design.In a first general classification, the methodology is composed by point-to-point and spatial calibration. The point-to-point calibration methodologies are used when there is instrumental data to calibrate hindcast data in a position where the wave climate is similar to the study location. Instead, we have defined a spatial calibration to calibrate the hincast data in an area, with instrumental data from other position that have different wave climate to the location under study.All calibration methodologies have been applied to the Spanish coastal area, it is calibrated the SIMAR-44 hindcast database (Spanish National Ports and Harbours Authority, OPPE) with instrumental data (buoys and satellites).

Winds and wind wave climate are two important phenomena for Black Sea basin. Wind wave climate has an important role on design of coastal structures and naval transportation. Despite this fact the wind wave climate is not well known for the Turkish coasts because of limited studies on this subject. The purpose of the present study was to further understand wind and wind wave climate along the Black Sea coastline of T&uuml / rkiye. For this purpose wind and wind wave data for every 65 months is obtained from ECMWF for and analyzed for 12 locations situated along Black Sea coast of Turkey. For every location the wind [Berk&uuml / n,2007] and wind wave roses, significant wind wave height vs. Mean wave period relations, extreme probability distribution and log-linear cumulative probability distribution are presented. Also a comparison with previous studies is given for better understanding the wind and wave climate better.

A program for selecting the optimal wave conditions for morphodynamically accelerated simulations of coastal evolution (‘OPTIWAVE’) has been constructed using a novel Genetic Algorithm approach. The optimization routine iteratively reduces the complexity of an incident wave climate by removing the events that contribute least to a target sediment transport pattern, and then ‘evolving’ a new set of weights for the remaining wave conditions such that the target sediment transport pattern (and magnitude) is optimally maintained. The efficacy of OPTIWAVE to satisfactorily reduce the incident wave climate is tested against three coastal modeling paradigms of increasing complexity: (a) A simple 1-D beach profile model (no tides); (b) A 2-D micro-tidal beach; (c) A tidal inlet, where the interaction between waves, tides, and wave-current interaction, adds significant complexity. The simple test case for a beach profile shows that OPTIWAVE is successfully capable of maintaining a target profile-integrated long-shore sediment transport rate. The calculated skill and RMSE of the reduced wave climate is a good indicator of its ability to reproduce the target sediment transport pattern. The optimal number of wave conditions is identified by an ‘inflection point’ at a critical number of wave conditions, where less complex a wave climate results in substantially reduced skill (increased error). The assumption that the ability of OPTIWAVE to reproduce a target sediment transport field is a valid proxy for the potential skill of a morphologically accelerated simulation is assessed for the case of a 2D micro-tidal beach. The skill of the accelerated models, which use a state-of-the-art ‘event-parallel’ method of simulating bed evolution from multiple wave conditions in parallel, is tested against a ‘brute force’ reference simulation that considers the full wave forcing. A strong positive correlation is found between the skill of the reduced wave climate to reproduce a target sediment transport pattern, and the resultant skill of the accelerated morphodynamic model against the ‘brute force’ reference simulation. Finally, the ability to combine reduced wave and tide climates for simulations that must consider both wave and tidal forcing, is assessed against a ‘brute force’ reference simulation of the seasonal evolution Ancao inlet, Algarve, Portugal. The reference simulation is validated against a comprehensive field dataset collected in 1999, and is shown to qualitatively reproduce key features of inlet behavior over a seasonal period. The combination of reduced wave and tidal climates in accelerated ‘event-parallel’ models did not successfully reproduce the reference seasonal morphological evolution of Ancao inlet. Assessing the model Brier Skill Score showed that the model was more successful in reproducing the reference morphology in areas dominated by tidal forcing, but did not have any predictive power in regions where morphological evolution is due to some combination of both wave and tidal processes.