The state of North Carolina is home to some of the most spectacular barrier islands in the world. These features are constantly shifting, impacted by waves, tides, and wind. Studies of the Outer Banks, North Carolina have resulted in varied results, but a detailed analysis of the barrier system as a whole is lacking. Using historic topographic surveys (T-sheets) from the 19th, the positions of various barrier segments were analyzed in relation to modern imagery. Changes in area, width, and center line locations were evaluated over the past 150 years. In total, 74 percent of modern transects have decreased in area. Total reductions in size were 130 km2 for the study period. Mean centerlines as a function of migration showed that 53 percent of segments were demonstrating directional movement away from the ocean. The average movement towards the bay between modern and historic centerlines was 8 meters. Thusly, barrier islands in North Carolina are demonstrating both decreases in total area and directional movement inland in response to sea level rise.

The impact of Hurricane Sandy (October 2012) on the Atlantic Coast of the United States resulted in massive overtopping (aggradation) of coastal barriers, along with localized overwash and breaching. A combination of high-frequency ground-penetrating radar (800 MHz GPR), low-field magnetic susceptibility (MS), and textural and mineralogical analyses was used to reconstruct the sedimentological and hydrodynamic parameters of the storm surge at two New Jersey sites immediately north of hurricane landfall: 1) Mantoloking and 2) Island Beach State Park (IBSP). Mantoloking represents a developed, scour-channelized backdune area with a 30-60 cm thick deposit consisting of 20-23 event horizons. Geophysical images reveal gently landward-dipping reflections. In contrast, IBSP site is a broad (width: 40 m) vegetated dune swale. GPR transects show landward-dipping tangential-oblique reflections as well as a conformable channel cut-and-fill structure (width: 7 m; depth: 1.5 m), producing a 0.7-1.5-m-thick deposit with 24-30 horizons. Within each sand-dominated event horizon, an upward 5-15% increase in mean grain size and 80-100% decrease in MS highlight the importance of hydrodynamic equivalency in lithological segregation within mixed-density fractions. Basal sub-layers enriched in heavy minerals (magnetite, ilmenite, garnet) yield MS of 100-350 μSI, in contrast to <40 μSI in quartz-rich upper sub-layers and pre-storm deposits. Several peaks in MS values correspond to an up to 65% increase in threshold shear stresses associated with individual unidirectional surge flows, with several most-enriched event horizons likely corresponding to waning-stage storm surge peaks recorded by offshore buoys. The sharp contact with the pre-storm surface produces distinct GPR reflections that allow accurate mapping of the thickness and extent of hurricane deposits. Together with potential correlation between lithological anomalies and high amplitude georadar signal return, the approach used in this study has applications to reconstructing event deposits in Quaternary sedimentary records. The new research findings have potential implications for reconstructing surge dynamics of recent hurricane events as well as quantitative hindcasting of hydrodynamic conditions responsible for lithologically diverse intervals in ancient tempestites. / Geology / Accompanied by two .xls files (Microsoft Excel).

Thesis (M.S.)--North Carolina State University, 2004. / Title from PDF title page (viewed on Apr. 3, 2005). Includes vita. Includes bibliographical references.

Patterns of the expansion of woody cover into grasslands on barrier islands of the Virginia coast were investigated. Seed dispersal of the dominant shrub Morella spp., was sampled deploying seed traps (n = 82) throughout a landscape under shrub encroachment pressure on Hog Island, VA. Traps were placed underneath: fruiting Morella, non-fruiting Morella, co-occurring species (Iva frutescens and Baccharis halimifolia) and in grass land, (no shrub cover). Environmental filters that act upon dispersed seeds and subsequently determine establishment patterns were also investigated. Dispersal distribution throughout the encroachment zone was leptokurtic and dispersal among cover types suggest co-occurring shrub species facilitate dispersal by functioning as bird perches. Interaction of biotic and abiotic factors mediate a complex process of establishment by influencing dispersal, germination and seedling survival to ultimately determine distribution patterns of woody plants in coastal environments.

It is important to understand mechanisms that facilitate expansion of two common shrubs, Morella cerifera and Baccharis halimifolia in coastal environments. The purpose of my study was to investigate the physiological and structural changes that occur as leaves age. Photosynthesis, incident light, chlorophyll, and leaf C:N ratios were quantified for young, intermediate, and old leaves (distal, central and proximal leaves, respectively). Leaf structural differences were also compared. Leaves did not change morphologically with age. Light decreased with leaf age and during winter months. Photosynthesis showed no seasonal or age related patterns. Chlorophyll increased initially and then declined with age due to self shading. Nitrogen content was highest during spring. Seasonality and leaf age had unique effects on the two study species. Understanding senescence adaptations of these two shrubs can help explain their abundance in coastal ecosystems.

Many recent studies have sought to understand the response of barrier islands and their attendant marshes to sea level rise. The Mississippi River delta plain, specifically the Chandeleur Islands and associated interior wetlands in eastern Louisiana, serves as an excellent natural laboratory for studying these responses. This region is presently undergoing the highest rates of shoreline erosion (> 15 m yr -1) in North America as wetlands are converted to open water in a regime of subsidence-driven rapid relative sea-level rise (~1 cm yr-1). Three conceptual models were developed based on the geomorphic relationships observed in the marsh that describe and predict shoreline processes as the Chandeleur Islands continue to disintegrate and submerge. These models indicate that shells are the dominant shoreline-forming material in the marsh due to the lack of sand-rich strata in the subsurface of the marsh.

Hurricanes can temporarily disrupt seasonal patterns of fish assemblage change or result in permanent changes in fish assemblages. I studied the effects of two hurricanes on fish assemblages at the Chandeleur Islands and the possible influence that storm-generated tidal channels may have on the composition of local fish assemblages. I also compared recently collected data to historic ichthyofaunal survey data collected over thirty years ago at the Chandeleur Islands. Near shore fish assemblages changed the most after hurricanes but changes in species composition were primarily due to increases in abundance and diversity. During July 2007 there was no significant difference between fish assemblages in channel and seagrass habitats, although significant differences among wash-over channels existed. Loss of habitat and the increased intensity and frequency of recent storms may explain why current fish assemblages at the Chandeleur Islands are less diverse (as measured by taxonomic distinctness) than assemblages collected during 1969-1971.

Tidal inlets play a significant role in barrier island sustainability along the barrier islands of southern Louisiana. With increasing tidal prism, major changes are taking place within and adjacent to the inlets. The purpose of this thesis is to examine how Caminada Pass, a tidal inlet along the Caminada-Moreau headland, has evolved through time. Fundamental to this effort is evaluating which processes have contributed toward inlet evolution and what is the response of the inlet-bordering barrier island shorelines of Grand Isle and Elmer’s Island. This effort summarizes previous results and utilizes published bathymetric data, aerial photographs, vector shorelines, satellite images, and seafloor grab samples. The intent of this research is to document the variety of data that are available for future studies of Caminada Pass, an evaluation of long and short-term changes to the system, and an overall better understanding of the inlet dynamics of Caminada Pass.

A Ilha Comprida, localizada no litoral sul do Estado de São Paulo, é uma ilha-barreira arenosa holocênica de 63 km de comprimento por até 5 km de largura, limitada a SW pela desembocadura de Cananéia, e a NE, pela desembocadura de Icapara. Seu sistema praia - duna frontal teve grande variação no tempo, como evidenciado por sucessivos truncamentos de cordões litorâneos. Em escala de tempo mais restrita, dentro dos últimos 200 anos, coberta pelo registro histórico e cartográfico e por fotografias aéreas, as mudanças morfológicas mais significativas concentram-se no extremo nordeste da ilha. Incluem a variação de largura na área hoje caracterizada pelo máximo estrangulamento da ilha, a formação de um pequeno campo de dunas transgressivo nesta mesma área, o surgimento em 1943 de uma projeção da linha de costa, atualmente em estágio avançado de erosão, e o aparecimento intermitente e sucessivo de embaiamentos lagunares no setor adjacente da ilha de Iguape. A abertura do canal artificial do Valo Grande, em 1852, atuou de modo direto ou indireto em pelo menos parte destas mudanças. O aumento de vazão, de retrabalhamento de sedimentos arenosos e portanto de aporte de carga de fundo, devido ao Valo Grande, induziu o surgimento de ilhas arenosas e a formação de ?manchas de areia? no fundo do canal lagunar, bem como a intensificação da dinâmica de meandramento da desembocadura de Icapara, implicando possível aceleração na migração desta desembocadura rumo NE e no próprio crescimento longitudinal da barreira. O sistema praia - duna frontal da Ilha Comprida apresenta também grande variação no espaço, evidenciada pela alternância ao longo de sua extensão de morfologias diferentes, o que pode ser atribuído à intercalação entre setores de caráter deposicional e erosivo. As extremidades da barreira caracterizam-se pela ocorrência marcante de pequenos campos de nebkhas sobre terraços baixos de dunas frontais (<0,5 m). A presença dessas feições pode ser relacionada à contínua progradação próximo às desembocaduras lagunares de Icapara e de Cananéia. A zona erosiva mais evidente encontra-se na extensão centro-sul da praia, como evidenciado pela ocorrência de cordões antigos truncados pela linha de costa atual, e pela redução em tamanho de dunas frontais ativas incipientes e estabelecidas, as quais aparecem por vezes com falésias vivas associadas. Na mesma região, a morfodinâmica muda de regime dissipativo para intermediário, com presença de cúspides de espraiamento e berma. Esta região, ademais, concentra a mais alta variabilidade e complexidade de morfologia de dunas (i.e. cordões de dunas incipientes e estabelecidas obliquamente amalgamadas), além de uma concentração maior de dunas do tipo rampa. No restante do sistema, predomina ampla face de praia de baixa declividade (média de 0,66o), com tendência para formas mais estáveis de dunas frontais (terraços e cordões). Medidas estatísticas de distribuição granulométrica (diâmetro médio, desvio-padrão e assimetria) obtidas através do método dos momentos de Pearson, permitiram inferir, pela regra de McLaren, duas células de deriva litorânea longitudinal principais. A célula nordeste, dirigida para NE, abrange aproximadamente 53 km, e a célula sudoeste toma em sentido oposto (SW) os restantes 10 km. As duas zonas de pólo deposicional de deriva são caracterizadas por amplos e baixos terraços de dunas frontais incipientes progradacionais. A zona de divergência entre as células de deriva coincide com a região de erosão costeira mais intensa. A distribuição em massa de minerais pesados é concordante com o transporte longitudinal verificado. Responde a isso a tendência de aumento de minerais de menor equivalente hidráulico (em geral, quimicamente mais instáveis) a despeito da redução de minerais de equivalente hidráulico mais alto (em geral, quimicamente mais estáveis) no rumo de transporte. A integração dos resultados obtidos por análise morfológica (fotointerpretação e estudo de feições de campo) e sedimentológica (granulometria e minerais pesados) permitiu estabelecer um modelo morfodinâmico para o sistema praia - duna frontal recente da Ilha Comprida. Neste modelo, a fase final de evolução da ilha é atribuída tanto à superação do obstáculo ao crescimento longitudinal exercido pelo morro de Icapara, quanto ao incremento de carga sedimentar na desembocadura de Icapara, induzido pela abertura do Valo Grande. / Ilha Comprida is a Holocene sandy barrier-island located on the south coast of São Paulo State, 63 km long and 2 to 5 km wide. Its transverse boundaries are Cananéia and Icapara inlets, at the SW and NE, respectively. The beach-foredune system of Ilha Comprida have experienced intense morphological variation in time, as showed by the successive truncations of littoral ridges. In a more restricted time-scale (at least 200 years) as covered by historical and cartographic records and aerial photographs, the most relevant changes have occurred on the northeast extremity of the island. These changes include: i) variation in width at the present most narrow region; ii) formation of a little transgressive dunefield (2 km2) in the same region; iii) initiation (in 1943) of a projection in the coastline, actually in advanced erosional state; iv) intermittent and successive appearing of lagoonal embayments at the neighboring sector of the Iguape island. The opening of the Valo Grande artificial channel, in 1852, acted either directly and indirectly on these changes. The increase of sedimentary bed-load supply induced the appearance of sand islands and submerged sand patches along the lagoonal channel. Beside this, the increasing meandering of Icapara inlet forced its rapid migration to the NE, and the longitudinal growing of the barrier. The beach-foredune system also shows great variability alongshore, observed on the morphologic alternance of depositional and erosional sectors. The tips of the barrier are characterized by the marked occurrence of small nebkha fields on foredune terraces (up to 0.5 m high). These aeolian morphological features can be related with a continuous progradation nearly Icapara and Cananéia inlets. The most-evidenced erosional zone stays at the mid-southwestern portion of the beach, as observed on the truncation of former beach and foredune ridges by the present coastline, and on the reduction in size of active incipient and established foredunes (that often appears with active cliffs). In the same region, the coastal morphodynamics changes from dissipative to intermediary beach, with presence of swash cusps and berm. Moreover, this site concentrates the highest variability and complexity of dune morphology (e.g. obliquely amalgamated incipient and established foredune ridges), beyond a increasing occurrence of ramp foredunes. In the remains of the beach-dune system, large shorefaces of low declivity (0.66o in mean), with tendency to more stable shapes of foredunes (terraces and ridges), are dominant. Statistical measures on the distribuition of granulometric frequencies (mean diameter, standard deviation, skewness), calculated through the Pearson?s moments method, indicate according to the McLaren rule two main longshore drift cells. The northeastern cell, oriented towards the NE, comprises about 53 km. The southwestern cell, comprising the remaining 10 km, is oriented towards the SW. The two depositional poles of longshore drift cells are characterized by wide and flat progradational, incipient foredune terraces. The divergence zone among these longshore cells drift coincides with the zone of the most intense coastal erosion. The mass distribution of heavy minerals is in agree with the deduced directions of longshore transport. This fact is confirmed by the tendency of increasing concentration of minerals with minor hydraulic equivalence (usually, more unstable minerals) in despite of reduction of minerals with high hydraulic equivalence (usually, more stable minerals) along the net longshore drift direction. The integration of data obtained by morphologic analysis (interpretation of aerial photographs and field features) and sedimentology (grain size, heavy minerals), allowed to postulate a morphodynamic model for the recent beach-foredune system of Ilha Comprida. According to this model, the late phase of barrier evolution is related both to the surpassing an obstacle to longitudinal growth (Icapara hill), and to the increasing sedimentary input at the Icapara inlet, favored by the opening of the Valo Grande channel.

Islands have been characterized based on vegetation and topography as exhibiting different disturbance regimes - reinforcing or resisting. This study had two objectives: quantify barrier island upland migration and vegetation cover change over 32 years (1984-2016), and assess tolerance of two prevalent dune grass species, A. breviligulata, and S. patens to sand burial. Using Landsat imagery from the Virginia Coast Reserve, islands were categorized within the disturbance resistance/reinforcing framework based on dune elevation. Resistant areas were associated with woody cover and low marsh to upland migration while reinforcing areas had low vegetation cover and high rates of migration. System-wide, migration rates increased over time and large losses of upland and marsh, paired with expansions of woody cover occurred. In the field, each grass species was subject to repeated burials. S. patens was able to maintain biomass and height in high rates of burial, whereas A. breviligulata did not survive.