Nearshore processes on barred beaches are studied with a process-based numerical model. The two major goals of the study are to expand the body of knowledge about nearshore processes on barred beaches gaining a better understanding of the physical mechanisms affecting bar migration events and to enhance the numerical model in order to accomplish realistic simulations of bar migration events on storm time scales. The numerical model is used to study the effect of physical processes on the hydrodynamics and morphodynamics in the nearshore environment. The numerical model system consists of a linear spectral refraction-diffraction model, REF/DIF S, a quasi-3D nearshore circulation module, SHORECIRC, energetics-based sediment transport models, and a morphological evolution model. A laboratory experiment with an offshore bar migration case followed by an onshore bar migration case is used for modeling purposes and verifications. A number of enhancements are made to the wave and circulation modules of the numerical model system specifically for simulations on barred beaches. The model modifications and enhancements are: a combined breaking wave parameter with a spatial variation in the wave model, a method accounting for breaking wave persistence in the wave model, a method accounting for the new breaker roller lag in the wave model, the dynamic pressure component in the radiation stress forcing, a roller contribution with different depth variation options for the short wave forcing in the circulation model, wave height instead of water depth as the turbulent length scale in the eddy viscosity calculations in the circulation model, and a slope term for the default sediment transport formula. The effect of surface shape parameter and the roller face angle on radiation stress and mean water level predictions are investigated. In reality, the organized wave energy is transferred to roller development over a transition distance and the roller does not immediately contribute to the radiation stresses; therefore, showing the importance of the roller lag mechanism for mean water level predictions. The cross-shore variation of the vertical momentum balance is studied to observe the variation of forcing agents of the undertow current. The cross-shore pressure gradient is the most dominant forcing term affecting the depth structure of the undertow current. The effect of different depth variations of the roller contribution to the short wave forcing on the undertow current is investigated. The mechanism accounting for breaking wave persistence and the mechanism accounting for the roller lag are shown to be important for predictions of the undertow currents on barred beaches. The skewed wave orbital velocities are introduced to the linear wave model by an empirical parametrization method and are found to contribute strongly to the onshore bar migration. The enhancements made to the wave dissipation and roller are found to significantly affect the predicted migration of the bar as well as the maintainance of the trough.

Dredging is often conducted to maintain authorized depths in coastal navigation channels. Placement of dredged sediment in the form of nearshore berms is becoming an increasingly popular option for disposal. Compared to direct beach placement, nearshore berms have fewer environmental impacts such as shore birds and turtle nesting, and have more lenient sediment compatibility restrictions. Understanding the potential morphological and sedimentological evolution is crucial to the design of a nearshore berm. Furthermore, the artificial perturbation generated by the berm installation provides a unique opportunity to understand the equilibrium process of coastal morphodynamics. Matanzas Pass and Bowditch Point, located on the northern tip of Estero Island in west-central Florida were dredged in October 2009. The dredged material was placed approximately 600 ft offshore of Fort Myers Beach and 1.5 miles southeast of Matanzas Pass, in the form of an artificial berm. Time-series surveys and sediment sampling were conducted semi-annually in order to quantify sedimentological characteristics and morphological changes within the first year after construction of the berm. The artificial berm at Fort Myers Beach is composed mainly of fine sand. Patches of mud were found throughout the study area, with the highest concentrations being in the trough landward of the berm, and offshore southeast of the berm area. The highest concentration of carbonates was found in the swash zone, as well as at the landward toe of the berm, which coincides with the coarsest sediment. The overall mud content of the berm is lower than that of the dredged sediment, thus indicating a coarsening of the berm over time. The reduction in fines as compared to the original dredged sedimet could also indicate a selective transport mechanism that moves finer material offshore, and coarser material landward, a desirable trend for artificial berm nourishment. During the course of the first year, the berm migrated landward and increased in elevation. Onshore migration occurred mostly within the first 6 months. Along with onshore migration, the shape of the berm changed from a symmetrical bell curve to an asymmetrical shape with a steep landward slope. There is no clear spatial trend of volume change alongshore within the berm area, indicating that sediment transport is mostly cross-shore dominated. A salient was formed landward of the northern portion of the berm. Several gaps were created during berm construction due to dredging and placement techniques. These dynamic gaps are likely maintained by rip currents through them. This study showed that the Fort Myers Beach berm is active, due to its landward migration during the first year after construction.

Orientador: Sueli Yoshinaga Pereira / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Geociências / Made available in DSpace on 2018-08-21T19:52:48Z (GMT). No. of bitstreams: 1 Costa_MarcelloAlves_D.pdf: 5073281 bytes, checksum: 027ba899f00acc6bc233ace29fbdc052 (MD5) Previous issue date: 2012 / Resumo: As discussões sobre a paisagem, seus cenários através dos tempos, seu comportamento dinâmico e a integração das atividades humanas com o meio físico, no qual estão inseridas são de profundo interesse de diversas ciências buscando assim novas formas de compreender o momento presente. Inundações, enchentes, desmoronamentos, chuvas intensas e marés muito elevadas passaram, nos últimos anos a fazer parte de nosso cotidiano informacional. Sendo assim, este trabalho apresenta uma proposta de análise em escala municipal abordando os eventos denominados de marés extremas que podem ocasionar diversos problemas às infra-estruturais como inundações e erosões costeiras, transformando a paisagem. As análises propostas partiram da detecção de eventos de marés extremas para os anos de 2002, 2003, 2004 e a relação com os períodos lunares de quadratura e sizígia. Utilizando-se da técnica estatística de Regressão Linear Múltipla, avaliou-se em escala anual e para semana que antecede os eventos extremos, as relações existentes de Variação de Maré extrema com a Temperatura, a Velocidade do Vento, as Chuvas e a Umidade Relativa. Analisou-se também a transformação da paisagem de forma temporal com um intervalo de 20 anos (1987 - 2007), frente aos parâmetros - Uso da Terra, Índice de Vegetação por Diferença Normalizada (NDVI) e as Variações da Temperatura, onde os resultados obtidos nas análises apontaram para supressão de áreas naturais, o adensamento da malha urbana, assim como um aumento da temperatura entre os anos. Os estudos apontaram detectaram que as marés extremas estão relacionadas ao evento do El Nino, em que foram observados marés da ordem de 1,2 a 1,92 metros (exagerei). Os ventos, a umidade e a temperatura, apesar de baixa correlação, são componentes que indicam a presença de sistemas frontais que proporcionam variações extremas. As marés altas provocam inundação e erosão costeiras em áreas vulneráveis, que estão em processo de maior adensamento urbano e os resultados da simulação de maré extrema no município de Itanhaém - São Paulo - Brasil indicaram que as áreas mais afetadas são justamente as áreas que mais se adensaram ao longo do período monitorado / Abstract: Discussions on the landscape, their scenarios through the ages, its dynamic behavior and integration of human activities with the physical environment in which they operate are of deep interest in various sciences thus seeking new ways to understand the present moment. Floods, floods, landslides, heavy rains and high tides have passed much in recent years to be part of our daily informational. Therefore, this work presents a proposal for a municipal scale analysis covering the events called extreme tides that can cause many problems for infrastructure such as flooding and coastal erosion, transforming the landscape. The analyzes proposed departed detection of extreme tidal events for the years 2002, 2003, 2004 and compared with lunar periods of neap and spring tides. Using the statistical technique of multiple linear regressions was evaluated on an annual scale and week preceding extreme events, the relations of Variation of Tide with extreme temperature, the speed of the wind, the rain and Relative Humidity. It was also analyzed the transformation of the landscape temporally with an interval of 20 years (1987 - 2007), compared to parameters - Land Use, Vegetation Index (NDVI) and the variations of temperature, where the results in analyzes showed suppression of natural areas, densification of the urban as well as an increase in temperature among years. The studies showed that the detected extreme tides are related to the El Nino event, where tides were observed in the range from 1.2 to 1.92 meters (exaggerated). The winds, humidity and temperature, although low correlation, are components that indicate the presence of frontal systems that deliver extreme variations. The high tides cause flooding and coastal erosion in vulnerable areas, which are in the process of higher urban density and the simulation results of extreme tide in the city of Itanhaém - São Paulo - Brazil indicated that the most affected areas are precisely the areas that most denser over the period monitored / Doutorado / Geologia e Recursos Naturais / Doutor em Ciências

Coastal habitats are highly dynamic and vulnerable to landscape-level disturbances such as storms and restoration projects. Along the east coast of Florida these areas are particularly valuable as they provide significant nesting habitat for two sea turtle species, the threatened loggerhead (Caretta caretta) and the endangered green turtle (Chelonia mydas). This coast was heavily impacted by three major hurricanes in 2004 and in some areas by large restoration projects in 2005. Recent remote sensing methods allow for broad evaluation of the shoreline and thus the ability to assess sea turtle nesting habitat at a landscape scale. I collected nesting data for southern Brevard County, Florida from 1989 – 2005 and for Canaveral National Seashore, Florida from 1995 – 2005. I used LiDAR (Light Detection and Ranging) and IfSAR (Interferometric Synthetic Aperture Radar) remote sensing to map sea turtle nesting habitat in both areas following the 2004 hurricanes and any subsequent restoration. Canaveral National Seashore underwent no restoration while southern Brevard County received extensive restoration. Topographic variables (e.g., total sand volume, width, and slope) derived from the remote sensing data were compared across three time periods (pre-hurricane, posthurricane, and recovery period) and I compared nesting success data from 2004 to 2005. I built regression models for 2004 and 2005 to determine which topographic features influenced loggerhead and green turtle nesting the most. Green turtle nesting success declined from 2004 to 2005 only in highly restored areas while loggerhead nesting sucess declined throughout. Hurricanes caused a reduction in most of the topographic variables and restoration predominantly impacted aspects of the beach profile (e.g. slope and width). Loggerheads responded to profile characteristics (e.g. upper and lower iii beach slopes) though green turtles showed no consistent response to topography. The results indicate that both loggerheads and green turtles are sensitive to beach restoration, although loggerhead nesting is more influenced by beach morphology and green turtle nesting may be influenced more by other dune features such as vegetation cover.

Thesis (MScEng)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: As the world finds itself increasingly unable to avoid the negative impacts of the physical phenomena associated with climate change, adaptation to climate change has been brought to the forefront of the international agenda. The range of adaptation technologies available can be categorized into three basic strategies (IPCC, 1990): Protection, (managed) Retreat, or Accommodation. The practice of adapting existing developments and infrastructure in the coastal zone by the process of accommodation has not yet seen wide implementation as a formalised adaptation strategy. In order for a community to accept and successfully implement accommodation strategies, all community stakeholders are required to accept and live with a certain level of managed risk, and to also rethink the concept of failure. As a result, accommodation practices implemented globally have been closely related to fields such as risk - and disaster management. Structural innovations in the field of accommodation measures include advanced technologies to elevate existing buildings safely above flood levels, and even “amphibious” houses. In Cape Town, South Africa, the choice between protection, retreat or accommodation as an adaptation measure remains complex. Not much discussion has yet been generated concerning accommodation measures that could be implemented to reduce the risk to existing properties that are already inappropriately located in the risk zone (e.g. seaward of the coastal hazard line), by accommodating the dynamic coastal processes taking place. Accommodation has been found to be most feasible in Cape Town at case study sites with a stable, non- or slowly eroding shoreline, which are also subject to flooding. The elevation of buildings and the alteration of buildings for flood-proofing, in unison with proactive risk and disaster management, could be implemented to accommodate the impacts of flooding on affected infrastructure. Located on Cape Town’s Atlantic Seaboard, Bakoven serves as a case study sample of such a site where an accommodation-based adaptation solution could be feasible. Both global and regional downscaled climate models have been found to deliver a large range of future climate conditions. Assuming best estimate future predictions, Bakoven properties have been found vulnerable to extreme flooding during both status quo and future extreme events. Environmental conditions at Bakoven are favourable for the construction of piled foundations. Stringent environmental and heritage constraints imposed by local government would, however, render accommodation strategies unviable. It is recommended that government at all levels be willing to adopt a more flexible approach to governing coastal areas, to ensure that the regulations they impose remain as dynamic as the environments which they govern. The viability and possible benefits of accommodation measures, rather than protection or retreat approaches should be carefully considered on an individual case-by-case basis, in unison with the local community. / AFRIKAANSE OPSOMMING: Wêreldwyd is gemeenskappe besig om toenemend te ervaar dat hul nie die nadelige gevolge van klimaatsverandering kan vryspring nie. Juis daarom, is aanpassing tot klimaatsverandering noodsaaklik. Die verskeidenheid van beskikbare benaderinge tot klimaatsverandering aanpassing kan in drie hoof kategorieë ingedeel word, volgens die IPCC (1990): Beskerming, (stelselmatige) Retireer of Akkomodasie. Die aanpassing van bestaande infrastruktuur d.m.v. akkomodasie is nog nie wyd geïmplementeer as ‘n amptelike aanpassings strategie nie. Ten einde die sukses van ‘n akkommodasie strategie te verseker, sal gemeenskappe genoodsaak wees om ‘n sekere vlak van residuele risiko te aanvaar en die konsep van die ‘faling’ te herdefinieer. Akkommodasie oplossings wêreldwyd is daarom nouliks verwant aan risiko- en rampsbestuur. Innovasies in die struktuurindustrie om die risiko van klimaatsverandering te akkommodeer, sluit onder andere in die fisiese oplig van geboue na ‘n hoër, veilige vlak, en ook die bou van sogenaamde “amfibiese” huise. In Kaapstad is die bepaling van die mees gepaste en voordelige aanpassings oplossing, net soos in die res van die wêreld, kompleks. Die moontlikheid van die gebruik van akkommodasie benaderinge en tegnologieë, eerder as beskermingsstrategieë, is nog nie welbekend of algemeen geïmplementeer nie. Daar bestaan wel ‘n geleentheid om hierdie tegnologieë toe te pas in die geval van bestaande strukture wat seewaarts van die dinamiese kusproses lyn, geleë is. Hierdie studie het bevind dat akkommodasie oplossings moontlik suksesvol kan wees by spesifieke gevallestudies langs Kaapstad se kuslyn waar die kuslyn grootendeels stabiel is. Die oplig en verandering van geboue om vloedbestand te wees, tesame met proaktiewe risiko- en rampsbestuur maatreëls, word by sommige van hierdie gevallestudies aanbeveel om die impak van klimaatsverandering te akkomodeer. Bakoven, ‘n klein gemeenskapsbuurt op Kaapstad se kuslyn, is ‘n voorbeeld van ‘n geval waar ‘n akkommodasie oplossing moontlik goed kan werk. Globale klimaatsmodelle lewer ‘n wye reeks van toekomstige klimaatsvoorspellings vir die jaar 2063. Tydens die toets van die mees waarskynlike toekomstige klimaats-scenario, is bevind dat Bakoven kwesbaar is vir die verwagte vloeding a.g.v. seevlakstyging verwag teen 2063. Daar is ook bevind dat selfs tydens huidige storms, sommige strukture aan Bakoven se kus kwesbaar is. Die omgewingstoestande by Bakoven word beskou as voordelig vir die konstruksie van heipale as fondasies om die geboue hoër op te lig. As gevolg van streng munisipale regulasies met omgewings- en geskiedkundige bewaring as doel, is hierdie opsie egter nie moontlik nie. Dit word aanbeveel dat die regulasies wat deur regeringsamptenare daargestel word, aanpasbaar genoeg moet wees om die veranderende kusomgewing in ag te neem. Die moontlikheid en volhoubaarheid van ‘n akkommodasie oplossing, eerder as ‘n beskermings- of opgee benaderinge, moet deeglik ondersoek word vir elke ‘n individuele geval, in samewerking met die betrokke gemeenskap.

[Truncated abstract] With rapidly increasing population densities along coastlines and rising global sea levels, coastal protection has become a major concern for coastal communities. Predicting sediment transport in nearshore regions, however, is one of the most challenging tasks faced by coastal researchers in designing coastal structures or beach nourishment schemes. Although nearshore sediment transport mainly occurs in the longshore direction, cross-shore sediment transport is crucial in determining the shoreline evolution and beach morphology . . . This study investigated the factors influencing sediment re-suspension and cross-shore suspended sediment flux in the frequency domain through a series of field measurements conducted at several different locations and a numerical model. Only oscillatory flow components were examined and the mean flow components were not considered. Although many different factors such as cross-shore location with respect to breaker line, significant wave height to water depth ratio (Hs/h), normalised horizontal velocity skewness (<u³>/‹u²›³/²), median grain size (d50), breaker type, and wave groupiness appeared to influence the magnitude of cross-shore suspended sediment flux, bed ripples was identified as the major contributing factor in changing the direction of suspended sediment flux due to incident swell waves. Moreover, the direction changed significantly with ripple type. High frequency measurements, obtained to examine the influence of turbulent kinetic energy (TKE) on higher sediment suspension events observed under wave groups indicated that higher TKE was generated at the seabed by approaching wave groups, which in turn resulted in higher suspension events.°1

The coastline of the city of Aracaju in Sergipe/Brazil, extending approximately for 24 km, is limited by the mouth of the Sergipe river in the north and the mouth of Vaza-Barris river in the south. In this work 7 beaches along Aracaju littoral were studied (Mosqueiro, Refúgio, Náufragos, Robalo, Aruana, Atalaia and Artistas), comprising 24 sampling points. The purpose of this dissertation is to outline the erosion and accretion processes of the Aracaju coastal area by using geoindicators of coastal erosion and accretion. The methodology included field campaigns over rainy (Aug/12) and dry (Feb/13) seasons, spatial geoindicators data, human settlement mapping and the development of coastal erosion vulnerability and risk maps using the ArcGIS 9.3.1 program. The Aracaju coastal area is characterized by beaches (ocean and estuary), surrounded by Quaternary sedimentary deposits predominantly from wind (foredune) and, by anthropogenic containment structures against coastal erosion. The erosion process is more effective on the beaches situated in contiguous areas to the mouths of Sergipe River ( Praia dos Artistas ), Vaza-Barris River ( Praia do Mosqueiro ) and in the middle of the beach arc ( Praia do Refúgio and Praia dos Náufragos , in the rainy season). The settlement level is high on the beaches of Praia da Atalaia , Praia dos Artistas , and non-existent on the beach of Praia do Mosqueiro . The coastal erosion vulnerability is high to moderately high on the beaches of Praia dos Artistas , Praia do Mosqueiro , Praia do Refúgio , Praia dos Náufragos , Praia da Aruana and Praia da Atalaia ; and moderately low to low in the other beaches. Depending on the coastal erosion vulnerability index and the human settlement level, the risk of coastal erosion is high on the beach of Praia dos Artistas and moderately high on the beaches of Praia do Refúgio , Praia dos Náufragos and Praia da Atalaia ; and moderately low to low in the other beaches. Although the coast of Aracaju pointed out a high risk just on the beach Praia dos Artistas , attention should be given to areas most vulnerable to erosion due to the intensification of human settlement over recent decades. The results of this study provide baseline information for environmental planning in the area analyzed, especially with regard to the human settlement near to the shoreline. / O litoral do município de Aracaju, Sergipe, com cerca de 24 km de extensão, é limitado a norte pela desembocadura do rio Sergipe e a sul pela desembocadura do rio Vaza-Barris. Neste trabalho foram estudadas 7 praias do litoral de Aracaju (Mosqueiro, Refúgio, Náufragos, Robalo, Aruana, Atalaia e Artistas), totalizando 24 pontos amostrais. O objetivo dessa dissertação de mestrado é caracterizar o processo de erosão e de acumulação do litoral do município de Aracaju através da utilização de geoindicadores de erosão e de acumulação costeira. A metodologia incluiu campanhas de campo no período chuvoso (agosto/2012) e no período seco (fevereiro/2013), espacialização dos dados de geoindicadores, e mapeamento da ocupação humana e elaboração dos mapas de vulnerabilidade e risco à erosão costeira no programa ArcGis 9.3.1. O litoral de Aracaju caracteriza-se por apresentar praias, oceânicas e de desembocadura, bordejadas por depósitos sedimentares quaternários, predominantemente de origem eólica (dunas frontais), e por estruturas antrópicas de contenção à erosão costeira. O processo erosivo é mais efetivo nas praias situadas nas áreas contíguas às desembocaduras dos rios Sergipe (Praia dos Artistas) e Vaza-Barris (Praias do Mosqueiro), e no meio do arco praial (Praias do Refúgio e dos Náufragos, no período chuvoso). O nível de ocupação é alto nas praias da Atalaia e dos Artistas, e inexistente nas praias do Mosqueiro. A vulnerabilidade à erosão costeira é alta a moderadamente alta nas praias dos Artistas, do Mosqueiro, do Refúgio, dos Náufragos, da Aruana e da Atalaia; e moderadamente baixa a baixa nas demais praias. Em função do grau de vulnerabilidade à erosão costeira e do nível de ocupação humana, o risco à erosão costeira é alto na praia dos Artistas e moderadamente alto nas praias do Refúgio, dos Náufragos e da Atalaia; e moderadamente baixo a baixo nas demais praias. Apesar do litoral de Aracaju apresentar risco elevado apenas na praia dos Artistas, atenção deve ser dada nas áreas mais vulneráveis à erosão em função da intensificação do processo de ocupação humana ocorrida nas últimas décadas. Os resultados deste estudo fornecem subsídios ao planejamento ambiental da área investigada, principalmente no que diz respeito à ocupação humana próxima à linha de costa.

<p> The Ontario shoreline of Lake Huron is one of the most populated areas, with reference to recreational purposes, in Ontario. However, with the rising water levels of the Great Lakes during 1972 and again in 1973, serious problems of beach erosion have resulted, particularly in the area of Grand Bend and Port Franks. This loss of sand has threatened cottages built on the dunes in addition to destroying breakwalls, steps, and boat launching ramps along the beach. It was with the idea of learning more about the beach, and possibly suggesting some methods of beach protection, that the research for this thesis was initiated. During the course of study, the author also became interested in the Ausable River and the associated flooding and erosion problems, with reference to past, present, and future attempts to solve or at least alleviate these difficulties. Thus, one section of the thesis is concerned with the Ausable River alone. </p> <p> The beach studied is actually the culmination of a series of raised beaches, formed during higher post-glacial lake stages. These raised beaches formed a bar separating the now non-existent Ausable Bay from Lake Huron, forming a lagoon eastward of the beach. This bar extends from Grand Bend, in a southwest direction, and culminates at Kettle Point. However, for the purposes of this thesis, that section between Grand Bend and Port Franks received the greatest amount of concentrated study. Over the years, the lagoon, formed by the growth of the bar has silted up, and is now drained for agricultural purposes. </p> <p> The modern beach was observed during the summer of 1972. This involved, profiling of a portion of the shore and offshore topography, procuring beach samples for later analysis, the use of sequential air photographs for observing changes over time, and the analysis of wind and wave data, along with many conversations with local residents and personal observations. </p> <p> The subsequent study of the above factors revealed several major conclusions regarding the beach. First, that it has good natural protection against erosion due to the abundance of sand s tored by the dunes. Second, the beach appears to be in an equilibrium state, however as lake levels fluctuate, so must the beach level, thus destroying the equilibrium for a period of time. With the lowering of the water level, the beach will become wider, exposing sand to the onshore winds, which will in turn rebuild the dunes with the blowing sand. Finally, because of the prximity of man-made structures to the beach, on the unstable dunes, some method of stabilizing the beach is necessary. That suggested is a groin system, designed and constructed by the local authorities. This would help prevent erosion and would eliminate the often vain and possibly dangerous, (to the natural environment), attempts by individuals to halt erosion. </p> <p> This is by no means a complete study of the area and its problems. Further consideration should be given to proposals which have been presented to the local conservation authority, and which were designed to alleviate some of these problems, particularly at Port Franks. The suggestions made here should also be given further thought. In addition to these practical problems, the actual growth of the original bar would provide an interesting subject for study. </p> / Thesis / Bachelor of Arts (BA)

North Carolina implemented a statewide mandatory oceanfront 30-year setback on June 1, 1979. This research evaluated the effectiveness of the setback policy in the town of Nags Head in protecting private property from ocean hazards, preventing the encroachment of structures on public beaches, and minimizing public costs of inappropriately-sited development. To date, no process has been established for evaluating the effectiveness of the setback program. This research is proposed as one way to evaluate the success of oceanfront setbacks on a local basis. The town of Nags Head, located on Bodie Island, was selected for analysis because it represents one of the most developed areas of the Outer Banks, and has witnessed significant growth over the past twenty years. Due to Bodie Island’s northeast orientation, Nags Head has experienced severe erosion in many areas, stemming in part from northeasters and other coastal storms. The research involved collecting data on structures built since June 1, 1979 within the study area. Oceanfront setbacks from the vegetation line at the time of construction were obtained from survey measurements, and field measurements taken in January and February 1994 determined the present location of the structure relative to the vegetation line. Site-specific erosion rates were then determined and compared to the long-term rate used by the Division of Coastal Management in the delineating oceanfront setback per lot. Predictions of the time until each structure would be located within the zone of imminent collapse, as defined by FEMA, were made based on both long-term erosion rates and actual rates occurring over each structure’s lifetime. These predictions were then compared to the years remaining until each structure was 25 years old (30-year setback less the 5-year zone of imminent collapse), and determinations of setback success or failure were made on a per lot basis. Results of the analysis yielded low setback success rates within the study area, raising doubts about the ability of long-term erosion rate setbacks to sufficiently protect oceanfront property in areas frequented by severe coastal storms. The research supports the continuation of the oceanfront setback program, but discusses policy shortcomings, suggests possible policy alternatives, and recommends topics for further research regarding oceanfront setbacks. / Master of Science

Shorelines are a primary source of attraction for the nearly two million tourists who visit Palm Beach County annually. Many of Palm Beach County beaches are located on barrier islands, separated by a series of inlets which serve as access points to the Intracoastal Waterway. However, inlets are often cited as a source of erosion, through interruption of littoral drift and interaction with nearshore hydrodynamics (e.g., causing wave diffraction or refraction). In an effort to mitigate potential negative impacts of the economically important tidal inlets, Palm Beach County has installed a sand transfer plant (STP) at two inlet locations, the Lake Worth Inlet and the South Lake Worth Inlet. Through analysis of annual aerial photography and beach profile surveys taken between 2000 and 2009, this study will determine what effect, if any, these sand transfer plants are having on the inlet-adjacent shorelines north and south of the two inlets with STP, as well as an inlet without an STP (Boca Inlet). This study hopes to increase the understanding of shoreline dynamics in Palm Beach County, which could recognize important alongshore patterns, such as the occurrence of erosional hot spots, to assist in future mitigation efforts. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2015. / FAU Electronic Theses and Dissertations Collection