Coarse-grained beaches are particularly prevalent in the UK, composed of accumulations of either gravel, or mixed sand and gravel sediments. The aim of the work presented in this thesis is to improve capabilities for predicting coarse-grained beach 2D profile development. In particular, the effects of infiltration and sediment sorting are considered. In this study, the public domain numerical model, XBeach (v12) is developed further. This model was initially developed for studying sandy environments especially for the case of dune erosion. Here, the model is modified to enhance its capability to predict beach profile change on coarse-grained beaches. Improvements include: use of Lagrangian interpretation of velocity in place of Eulerian for driving sediment movement; introduction of a new morphological module based upon Soulsby’s sediment transport equation for waves and currents; incorporation of Packwood’s infiltration approach in the unsaturated area of the swash region; and implementation of a multiple sediment fraction algorithm for sediment sorting of mixed sediments. These changes are suggested and justified in order to significantly improve the application of this model to gravel and mixed beaches, especially with regard to swash velocity asymmetry which is responsible for development of the steep accretionary phase steep berm above waterline and sediment sorting. A comparison between model simulation and large scale experiments is presented with particular regard to the tendency for onshore transport and profile steepening during calm conditions; offshore transport and profile flattening during storm conditions; and sediment sorting in the swash zone. Data used for this and the model calibration comes from the Large Wave Channel (GWK) of the Coastal Research Centre (FZK) in Hannover, Germany. The results are found to agree well with the measured experimental data on gravel beach profile evolution. This is due to the inclusion of infiltration in the model which weakens the backwash volume and velocity in a more satisfying manner than through the use of asymmetric swash friction and transport coefficient. The model also simulates sediment sorting of a mixed sediment beach. However, the profile comparisons were not satisfactory due to limitations of the numerical model such as the constant permeability rate used throughout the simulation and the non-conservation of the sediment volume in the laboratory data by an order of 50%. From the simulation, it was found that the fine sediment moves offshore and the coarser sediment moves onshore. This is because of infiltration weakens the backwash velocity; the coarser sediment moving onshore barely moves back offshore while the fine sediment remains in motion. This pattern agrees with the pattern obtained from sediment samples analysis in the experiment and provides an explanation for the existence of composite beaches. The model is also shown to be capable of switching from accretionary to erosive conditions as the wave conditions become more storm-like. Again, the model simulations were in a good agreement with the observations from the GWK dataset. Numerical model simulations on the effects of the tidal cycle on coarse-grained beach profile evolution were also carried out. This preliminary investigation showed that the model was able to predict the anticipated profile change associated with a coarse-grained beach under such wave and tidal forcing. Tidally forced accretion and erosion were compared with those predicted under similar beach sediments and wave conditions for constant water level. The main differences are that the affected area is wider and the berm is located on the upper beach during flood for both gravel and mixed beaches. Therefore, the model developed in this study can be seen to be a robust tool with which to investigate cross-shore beach profile change on coarse-grained beaches and sediment sorting on mixed beaches. Further work is also indicated.

Les cultures sportives s’expriment à travers des formes sans cesse renouvelées, soumises à des lectures, relectures, tensions, préemptions, propres à l’existence-même d’un phénomène social.Au sein de ce foisonnement, les pratiques physiques et sportives sur sable méritent une attention particulière. Nous avons choisi de les observer et donner à voir comme des productions et produits humains de l’instant présent, dans un environnement social où l’humain agit et interagit. Après avoir procédé à leur recension et classement, nous avons sélectionné quatre d’entre elles ‒ le beach volley, le beach tennis, le beach rugby et le char à voile ‒ afin de les analyser sous l’angle de ce que font et disent les pratiquants, au sein d’un système complexe, interdépendant, qui met en jeu pratiques, pratiquants et espaces de pratique. À cet effet, les observations, les entretiens, ainsi que les questionnaires que nous avons menés ont permis de montrer que les pratiquants des activités sur sable présentent des caractéristiques communes et des représentations partagées. Cependant, nous constatons que ces activités, le plus souvent saisonnières, drainent, non pas de nouveaux pratiquants, mais bien un public de sportifs qui s’adonne majoritairement à la version beach de son sport de référence, sans les contraintes calendaires des compétitions fédérales (continuité, rupture).Si les espaces de pratique sont décrits comme des territoires d’activités humaines où se créent du lien social, des découvertes, des loisirs et de la dépense physique, il n’en demeure pas moins qu’ils s’avèrent plus domestiqués que sauvages et que la quête de l’autrement et de l’ailleurs reste continûment à l’ordre du jour. / Pas de résumé en anglais

On the basis of coastal disaster mitigation and protection, a beach must have sufficient width for preventing the destruction to public facilities, as well as protecting the safety of life and private property during storm events. The requirement of such a horizontal extent from the initial shoreline to the probable erosion landward to safeguard against the onslaught of a storm is referred to as ¡¥storm beach buffer width¡¦. Upon neglecting the effects of global warming and sealevel rise on a beach and berm with profile in equilibrium, numerical calculations are conducted first to validate the range of the most important parameters (K »P £` ) in the SBEACH model using the results of profile changes available from the CERC¡¦s large wave tank (LWT) tests in 1960s. These results are then applied to assess the profile changes for a beach with a vertical seawall and the other without sufficient berm, subject to the normal incidence of storm waves over a specific duration. Finally, a total of 48 cases with sufficient beach width are then investigated, from which a multiple linear regression model is proposed to determine the extent of berm retreat, as well as the location and height of a submerged offshore bar, for the benefit of coastal profession on preliminary design of storm buffer. Our modeling results using SBEACH reveal that: (1) A seawall without or with insufficient fronting beach could result in serious scour at its toe and even the total loss of the entire beach berm; (2) A beach with sufficient berm, natural or artificially nourished, is capable of protecting the back beach, despite the temporary erosion in the early hours of a storm action; (3) Under the same conditions of wave height and period, a wide buffer is necessary for a beach with small mean sand grain, and the berm height should be designed at 1.6 times of the designed storm surge level, in order to effectively absorb storm wave energy and maintain the provision of a storm buffer; and (4) The multiple linear regression model proposed in this study can be used to evaluate the scour depth and retreat of the berm, as well as the width of a storm beach buffer, upon the input of wave conditions and mean beach sand grain etc.

Rip currents are the most dangerous hazard at surf beaches. Rip currents in South Florida have previously not been studied. Beach profiles for three Florida beaches (Miami Beach, Lido Beach, Sarasota, and Pensacola Beach) and one Georgia beach (South Cumberland Island) were chosen for surveying because of their variable sand bar heights. Rip current hazard at each beach was assessed by lifeguard rip rescue and drowning statistics. A relationship was found between sand bar height, beach slope and rip current hazard. Rip current measurements in South Florida, which involved utilizing GPS drifters, laser rangefinder and drone-imaged fluorescent tracer dye, showed that the speed ranged from 0.1-0.5 m/s, which is fairly slow compared to such measurements undertaken in California and Australia. The effect of rip currents on swimmers was analyzed based on the drag force acting on swimmers and the power they generate to overcome the currents when swimming against them. The drag force and power increase quadratically and cubically, respectively, with the increase of rip current and swimming speeds. Hence, even rip currents of low velocity can be dangerous and swimming against the current should be avoided if possible. Strong rips in California have been shown to exhibit a circulatory pattern, which could bring a floater back to the safety of a shallow sand bar. Field measurements of rip currents in South Florida clearly defined the flow characteristics of a nearly straight-line current, sometimes deflected to the east-southeast. Therefore, the traditional approach of swimming left or right, parallel to the shore is the best escape strategy, but not against the longshore current if present. A logistic regression analysis was conducted to predict the occurrence of rip currents based on beach conditions. The logistic model showed that wave height, wave period and wind speed were statistically significant factors in rip generation. Rips were found to be most commonly generated by relatively small, non-threatening waves (e.g., 0.6 to 0.9m in height). These physical factors, along with social and safety considerations, pose a significant problem for coastal management.

Este estudo tem como objetivo a previsão de impactos gerados por tempestades sobre os sistemas praial e de dunas frontais nas costas Leste (praias expostas) e Norte (praias abrigadas) da Ilha de Santa Catarina. A área de estudo abrange as praias entre a Barra da Lagoa e a Praia da Daniela. As respostas da costa frente aos eventos de tempestades foram classificadas em quatro diferentes regimes: Espraiamento (Swash), Colisão (Collision), Sobrelavagem (Overwash) e Inundação (Inundation). A delimitação entre cada regime é baseada na mais alta e mais baixa elevação vertical do nível d’água em relação às características morfológicas da duna frontal (base e crista). Para a Costa Leste, onde as praias são expostas à incidência de ondas, a máxima elevação do nível do mar foi definida pela soma do wave runup, maré astronômica e maré meteorológica, calculada para quatro distintos períodos de retornos (5, 10, 25 e 50 anos). A mais baixa elevação do mar foi definida como sendo a elevação na qual a praia é, na maior parte do tempo, continuamente submersa. Enquanto que para a Costa Norte, onde as praias são abrigadas da incidência das ondas, a máxima elevação do nível do mar durante eventos de tempestades foi calculada levando-se em consideração a soma das marés astronômica e meteorológicas para cada período de retorno analisado; enquanto que a mínima elevação foi representada pelo nível mais alto da maré astronômica. Em ambas as costas, foram adicionados os valores de elevação do nível do mar baseados nas previsões de pior caso do relatório do Painel Intergovernamental de Mudanças Climáticas. De acordo com este estudo a elevação do nível médio do mar vem ocorrendo em uma taxa de 4 mm/ano com uma aceleração anual de 0,019 mm/ano². Os resultados mostram que para a maioria das praias expostas não houve mudança de regime entre os períodos de retorno analisados. As exceções foram a porção central da praia dos Ingleses que apresentou passagem do regime de sobrelavagem (5 e 10 anos) para o regime de inundação (25 e 50 anos) e a Praia Brava que foi classificada como sujeita ao regime de colisão para o período de retorno de 5 anos passando a ser classificada como submetida ao regime de sobrelavagem para os demais períodos. O regime de sobrelavagem foi predominante para as praias abrigadas, sendo este o único regime registrado em toda a Costa Norte para o período de 50 anos. / This study aims to forecast the impacts of storms on the beache and foredune system along the East (exposed beaches) and North (sheltered beaches) coast of Santa Catarina Island. The study area covers the beaches between Barra da Lagoa and Daniela Beach. The coastal storm response were classified into four different regimes: Swash, Collision, Overwash and Inundation. The limits between regimes are based on the highest and lowest vertical elevation of the water level in relation to the elevation of geomorphic features of the foredune (base and crest). To the East Coast the maximum rise in sea level was defined as the sum of the wave runup, astronomical tide and storm surge, calculated for four different return periods (5, 10, 25 and 50 years). The lowest elevation of the sea is defined as the elevation at below which the beach is, most of the time, continuously subaqueous. On the North Coast the maximum rise in sea level during storm events was calculated taking into account the sum of astronomical and meteorological tides; the minimum level was defined as the maximum vertical range of astronomical tide for each return period. On both coasts the sea level rise (SLR) based on worst-case of the Climate Change Intergovernmental Panel report predictions was added to the maximun and minimum sea level elevation. According to this study the increase on the mean sea level has been occurring at a rate of 4 mm/year with an annual acceleration of 0.019 mm/ano². The results show that most of the exposed beaches did not change their regimes between the return periods analyzed. The exceptions being the Central-North portion of Ingleses, that went from overwash (RP 5 and 10 years) to inundation (RP 25 and 50 years) and Brava which changed from collision (RP 5 years) to overwash regime (RP 10, 25 and 50 years). Overwash was the predominant regime on sheltered beaches, being the only recorded regime for the 50-year return period.

Landsliding is a significant contributor to continuous erosion of the 150-mile northern Oregon coast. Direct loss of land to the sea by landslides occurs along 47 percent of the coast. The remaining 53 percent has minor shifting of sand along depositional areas such as spits and dunes. These minor movements alter coastal topography but do not erode material directly into the sea. The type of landsliding is principally controlled by the lithology of the coastline. Landslides are classified on the basis of two features: the lithology of the coastal material in the slide and the type of movement expressed by the overall shape of the slide. Slump occurs in deeply weathered sedimentary rocks and in marine terrace sands overlying seaward-dipping rocks. Rock and debris fall are mainly confined to headlands. Block glides develop along bedding planes of relatively unweathered sandstone. Debris shift occurs in thick terrace and dune sand deposits in which no slip surface is defined. Factors contributing to the cause of coastal landslides include high precipitation, easily weathered rock, and high coastal wave energy. Frequency of reported landslides is related to periods of high precipitation and high wave energy. Although rock weathering is continuous throughout the year, the final phase in disruption of slope equilibrium often occurs during winter storm conditions. Landslides on headlands and adjacent coastlines disrupt the most extensive land area. Wave refraction directly influences this relationship by focusing wave energy on promentories and on the coastline within one mile of the headlands. Distribution of coarse and fine beach material is affected by refraction in restricted coves. Severe coastal erosion has taken place in local areas. The average rates of retreat vary according to the lithology of the coastline, and have been determined as follows: unconsolidated sand and gravel - 23 feet per year; marine terrace sands overlying sandstone and clay - 20 feet per year; marine terrace sands overlying mudstone and sandy shales - 6.5 feet per year. Knowledge of the processes of marine erosion applied to local cliff protection measures can assist in increasing the effectiveness of erosion control attempts. / Graduation date: 1964

Swimming in ocean water, including beaches not impacted by known point sources of pollution, continues to pose a rising health concern. Studies which evaluate the relationship between indicator microbes, pathogens, and human health at recreational beaches are rare, especially at non-point beaches, although such studies are necessary for establishing criteria which would protect public health while minimizing economic burdens. The objective of this dissertation was to better understand the non-point source beach system, and hence determine possible directions that should be taken from a beach regulatory perspective in order to protect bather health and minimize economic burdens. This objective was accomplished through two studies. The first study included an initial evaluation of the presence of and associations among indicator microbes, pathogens and environmental conditions at a subtropical, recreational marine beach in South Florida (USA) impacted by non-point sources of pollution. Twelve water and eight sand samples were collected during four sampling events conducted at high or low tide and during elevated or reduced solar insolation conditions. Analyses included fecal indicator bacteria (FIB) (fecal coliform, Escherichia coli, enterococci, Clostridium perfringens), human-associated microbial source tracking (MST) markers (human polyomaviruses [HPyVs] and Enterococcus faecium esp gene), and pathogens (Vibrio vulnificus, Staphylococcus aureus, enterovirus, norovirus, hepatitis A virus, Cryptosporidium spp. and Giardia spp.). The objective of the second study was to capture a series of "snapshots" of the study beach with respect to pathogens and indicator microbe levels, environmental conditions, and cumulative human health effects. Two sets of daily composite samples were collected during the BEACHES epidemiology study conducted in Miami (FL) at the same non-point source subtropical marine beach. These samples were analyzed for several pathogens, microbial source tracking markers, indicator microbes, and environmental parameters similar to those in the first study. Enterococci concentrations in water and sand assessed by qPCR were greater than membrane filtration measurements in both studies. FIB concentrations in water were below recreational water quality standards for three of four sampling events; pathogens and MST markers were also generally undetectable during the first study. FIB levels exceeded regulatory guidelines during one event, accompanied by the detection of HPyVs and pathogens, including the autochthonous bacterium Vibrio vulnificus in both sand and water, the allochthonous protozoan Giardia spp. in water, and Cryptosporidium spp. in sand samples. These elevated microbial levels were detected at high tide, low solar insolation conditions, and after elevated 2 day antecedent rainfall. Analyses of the second study demonstrated that rainfall and tide were also significant factors in determining the presence of both indicator microbes and pathogens. Additional potential associations between environmental factors, microbes and human health effects were also identified. However, more analyses should be conducted as the limited number of samples renders it difficult to make conclusive statements about the relationship between these different factors. The results of this research demonstrate the complexity of beach systems characterized by non-point sources, and how more novel and comprehensive approaches will be needed to assess beach water quality for the purpose of protecting bather health. A recommended approach "The comprehensive tool box with approval process approach" to address the beach complexity is presented and applied to the study beach.

Taiwan is a small island state surrounded by the oceans but with large population. With limited land space, it would be worthwhile considering how to stabilize the existing coast or to create stable artificial beaches. Under the onslaught of storm surge and large wave from typhoons, beach erosion would occur accompanying by formation of a submerged bar beyond the surf zone with the sand removed from the beach. After the storm, the bar material maybe transport back by the swell and predominant waves which helps recover the original beach, thus producing a beach profile in dynamic equilibrium. The main purpose of this research is to use the back-propagation neural network¡]BPNN¡^, which trains a sample model and creates a system for the estimation, prediction, decision making and verification of an anticipated event. By the BPNN, we can simulate the key characteristic parameters for the storm beach profile resulting from typhoon action. Source data for training and verification are taken from the experimental results of beach profile change observed in large-scale wave tank¡]LWT¡^conducted by Coastal Engineering Research Center¡]CERC¡^in the USA in the 1960s and that from the Central Research Institute of Electric Power Industry in Japan in the 1980s. Some of the data are used as training pairs and others for verification and prediction of the key parameters of berm erosion and bar formation. Through literature review and simulation on the related parameters for storm beach profile, methodology for the prediction of the beach profile and bar/berm characteristics can be established.

With the ever increasing population and economic activities in coastal areas, coastal hazards have become a major concern for coastal management. The fundamental requirement of coastal planning and management is the scientific knowledge about coastal forms and processes. This research aims at developing algorithms for automatically extracting coastal morphological information from LiDAR data. The primary methods developed by this research include automated algorithms for beach profile feature extraction and change analysis, and an object-based approach for spatial pattern analysis of coastal morphologic and volumetric change. Automated algorithms are developed for cross-shore profile feature extraction and change analysis. Important features of the beach profile such as dune crest, dune toe, and beach berm crest are extracted automatically by using a scale-space approach and by incorporating contextual information. The attributes of important feature points and segments are derived to characterize the morphologic properties of each beach profile. Beach profiles from different time periods can be compared for morphologic and volumetric change analysis. An object-oriented approach for volumetric change analysis is developed to identify and delineate individual elevation change patches as discrete objects. A set of two-dimensional and three-dimensional attributes are derived to characterize the objects, which includes planimetric attributes, shape attributes, surface attributes, volumetric attributes, and summary attributes. Both algorithms are implemented as ArcGIS extension modules to perform the feature extraction and attribute derivation for coastal morphological change analysis. To demonstrate the utility and effectiveness of algorithms, the cross-shore profile change analysis method and software tool are applied to a case study area located at southern Monterey Bay, California, and the coastal morphology change analysis method and software tool are applied to a case study area located on Assateague Island, Maryland. The automated algorithms facilitate the efficient beach profile feature analysis over large geographical area and support the analysis of the spatial variations of beach profile changes along the shoreline. The explicit object representation of elevation change patches makes it easy to localize erosion hot spots, to classify the elevation changes caused by various mechanisms, and to analyze spatial pattern of morphologic and volumetric changes.

Open coastlines are dynamic environments which experience seasonal and long-term physical changes. Sandy beaches line much of this coastline. As part of the requirements for Ph.D., I conducted a study examining intertidal macrofaunal and sedimentological features along the upper Texas coastal from 2007-2009. Four sites near Sabine Pass, High Island, Jamaica Beach, and Surfside Beach were selected. Beach transects were established at each site with six intertidal stations identified for collecting macrofaunal sediment core samples. Although sandy beaches are low in species diversity, the taxa found survive under dynamic and harsh conditions. In disturbance dominated environments, sandy beach fauna tended to be influenced by physical factors, instead of biologically controlled ones. The taxa found in this study include primary and secondary successional organisms which are adapted to handle disturbances. 98% of the benthic specimens identified belonged to six taxa with 92% from two taxa, Scolelepis squamata (38%) and Haustoriidae (54%). Macrofaunal zonation varied between sites because of beach geomorphology. On September 13, 2008, Hurricane Ike made landfall on the upper Texas coast causing extensive damage and erosion. Roughly 0.5 m of vertical height was lost at each beach post-storm. Total macrofaunal abundance declined by 87% from pre-storm counts. During the recovery the dominant two taxa, Haustoriidae and Scolelepis squamata, made up 82.78% of the total benthic specimens identified with haustoriids making up 68% of the total benthic taxa. The beach community remained dominated by four of the previously identified, six most common and abundant taxa. Recovery of sandy beaches often was hindered by increased vehicular traffic, sand removal and cleaning. Beach ecosystems have shown a high natural ecological resilience, but do not preclude the possibilities of habitat extinction and/or catastrophic community regime shift. Beaches are highly susceptible to human exploitation and global climate change, such as sea level rise. Knowledge of beach macrofaunal diversity along the Texas coast, such as haustoriids, could be used to estimate beach health and better evaluate the upward effects of natural disturbance, pollution and human uses on an integral part of the coastal ecosystem.