published_or_final_version / Earth Sciences / Master / Master of Philosophy

A Barreira Costeira do Itapocú está localizada na porção norte do litoral do estado de Santa Catarina sobre os domínios dos municípios de Araquari e Barra Velha. Em sua porção central a barreira apresenta-se segmentada por influência da desembocadura do rio Itapocú. Registros históricos evidenciam a ocorrência comum, na barreira, de episódios de transposição de sedimentos devido à ocorrência de eventos de sobrelavagem. A barreira e os subambientes associados foram mapeados para os anos de 1938, 1957, 1978, 2005 e 2012. Adicionalmente, foram aplicados três índices de vulnerabilidade para os depósitos de sobrelavagem, conforme metodologia proposta por Garcia et al. (2010) – OSR, MOIR e CBO, e foram analisados os parâmetros granulométricos do sistema praia-duna atual e dos depositos de sobrelavagem em dois perfis transversais à barreira. A análise geomorfológica mostrou que as principais modificações observadas ao longo do tempo na BCI estiveram relacionadas à migração do canal de conexão da laguna com o oceano, anteriormente à sua fixação, bem como a eventos de sobrelavagem da barreira. Os depósitos de sobrelavagem apresentaram elevada frequência de ocorrência ao longo da barreira (OSR), onde a maior pôde ser observada no ano de 1957, atingindo 42% de todo o comprimento da barreira, em seu setor sul, e 60% no setor norte. Este padrão apresentou diminuição ao longo do tempo, e em 2012 cerca de 1% do comprimento do setor sul da barreira costeira apresentou sobrelavagem, enquanto o setor norte exibiu 19%. MOIR, índice referente às intrusões históricas de sobrelavagem e representando a recorrência de um máximo de intrusão, foi aplicado em intervalos de 10 metros e mostrou que eventos de transposição de sedimentos tendem a ocorrer todos os anos na área estudada, atingindo até 40 metros de intrusão. Para o ultimo ano de análise, 2012, o índice CBO apresentou três casos de valor máximo, indicando máxima vulnerabilidade de um rompimento da barreira costeira. No estudo comparativo entre os diferentes compartimentos do sistema praia-duna e dos depósitos de sobrelavagem não foi possível distinguir um claro padrão entre os subambientes com base nos parâmetros granulométricos. Entretanto, este padrão de não distinção pode indicar a usual influência de processos marinhos costeiros de sobrelavagem, atuantes sobre o sistema deposicional eólico. / The Itapocú coastal barrier is located in the northern coast of Santa Catarina State, on the domain of Barra Velha and Araquari cities. In its central part the barrier is segmented due to the influence of the Itapocú river mouth. Historical records demonstrate that the barrier experiments frequent overwash events. The barrier and associated environments were mapped for 1938, 1957, 1978, 2005 and 2012 dates. Additionally, three vulnerability indexes to the washover deposits were applied, according to Garcia et al. (2010) – OSR, MOIR and CBO, and the granulometric properties were analyzed for the modern beach-dune system and washover deposits in two cross sections. The morphological analysis showed that the main changes observed were related to inlet migration, before its fixation in 2011, and also to overwash events. The washover deposits showed high frequency of occurrence along the barrier (OSR), with the greater occurring in 1957, reaching 42% of its entire length in the south, and 60% in the north section. This pattern presented a decrease behavior over time, and in 2012 approximately 1% of the barrier length was overwashed in the south section and 19% in the north. The index MOIR, related to historical sediment intrusions of overwash processes, and representing a maximum intrusion was applied in 10m intervals and showed that washover events tend to occur in all years in the ICB, reaching 40m of intrusion. For the last year analyzed, 2012, the CBO index showed 3 situations of maximum intrusion, indicating 100% of barrier breaching vulnerability. In the comparative granulometric study, it was not possible to characterize the environmental deposits based on the granulometric parameters. However, non-discretize pattern can indicate the influence of coastal marine processes (overwash) acting over the eolian deposits.

A Barreira Costeira do Itapocú está localizada na porção norte do litoral do estado de Santa Catarina sobre os domínios dos municípios de Araquari e Barra Velha. Em sua porção central a barreira apresenta-se segmentada por influência da desembocadura do rio Itapocú. Registros históricos evidenciam a ocorrência comum, na barreira, de episódios de transposição de sedimentos devido à ocorrência de eventos de sobrelavagem. A barreira e os subambientes associados foram mapeados para os anos de 1938, 1957, 1978, 2005 e 2012. Adicionalmente, foram aplicados três índices de vulnerabilidade para os depósitos de sobrelavagem, conforme metodologia proposta por Garcia et al. (2010) – OSR, MOIR e CBO, e foram analisados os parâmetros granulométricos do sistema praia-duna atual e dos depositos de sobrelavagem em dois perfis transversais à barreira. A análise geomorfológica mostrou que as principais modificações observadas ao longo do tempo na BCI estiveram relacionadas à migração do canal de conexão da laguna com o oceano, anteriormente à sua fixação, bem como a eventos de sobrelavagem da barreira. Os depósitos de sobrelavagem apresentaram elevada frequência de ocorrência ao longo da barreira (OSR), onde a maior pôde ser observada no ano de 1957, atingindo 42% de todo o comprimento da barreira, em seu setor sul, e 60% no setor norte. Este padrão apresentou diminuição ao longo do tempo, e em 2012 cerca de 1% do comprimento do setor sul da barreira costeira apresentou sobrelavagem, enquanto o setor norte exibiu 19%. MOIR, índice referente às intrusões históricas de sobrelavagem e representando a recorrência de um máximo de intrusão, foi aplicado em intervalos de 10 metros e mostrou que eventos de transposição de sedimentos tendem a ocorrer todos os anos na área estudada, atingindo até 40 metros de intrusão. Para o ultimo ano de análise, 2012, o índice CBO apresentou três casos de valor máximo, indicando máxima vulnerabilidade de um rompimento da barreira costeira. No estudo comparativo entre os diferentes compartimentos do sistema praia-duna e dos depósitos de sobrelavagem não foi possível distinguir um claro padrão entre os subambientes com base nos parâmetros granulométricos. Entretanto, este padrão de não distinção pode indicar a usual influência de processos marinhos costeiros de sobrelavagem, atuantes sobre o sistema deposicional eólico. / The Itapocú coastal barrier is located in the northern coast of Santa Catarina State, on the domain of Barra Velha and Araquari cities. In its central part the barrier is segmented due to the influence of the Itapocú river mouth. Historical records demonstrate that the barrier experiments frequent overwash events. The barrier and associated environments were mapped for 1938, 1957, 1978, 2005 and 2012 dates. Additionally, three vulnerability indexes to the washover deposits were applied, according to Garcia et al. (2010) – OSR, MOIR and CBO, and the granulometric properties were analyzed for the modern beach-dune system and washover deposits in two cross sections. The morphological analysis showed that the main changes observed were related to inlet migration, before its fixation in 2011, and also to overwash events. The washover deposits showed high frequency of occurrence along the barrier (OSR), with the greater occurring in 1957, reaching 42% of its entire length in the south, and 60% in the north section. This pattern presented a decrease behavior over time, and in 2012 approximately 1% of the barrier length was overwashed in the south section and 19% in the north. The index MOIR, related to historical sediment intrusions of overwash processes, and representing a maximum intrusion was applied in 10m intervals and showed that washover events tend to occur in all years in the ICB, reaching 40m of intrusion. For the last year analyzed, 2012, the CBO index showed 3 situations of maximum intrusion, indicating 100% of barrier breaching vulnerability. In the comparative granulometric study, it was not possible to characterize the environmental deposits based on the granulometric parameters. However, non-discretize pattern can indicate the influence of coastal marine processes (overwash) acting over the eolian deposits.

A Barreira Costeira do Itapocú está localizada na porção norte do litoral do estado de Santa Catarina sobre os domínios dos municípios de Araquari e Barra Velha. Em sua porção central a barreira apresenta-se segmentada por influência da desembocadura do rio Itapocú. Registros históricos evidenciam a ocorrência comum, na barreira, de episódios de transposição de sedimentos devido à ocorrência de eventos de sobrelavagem. A barreira e os subambientes associados foram mapeados para os anos de 1938, 1957, 1978, 2005 e 2012. Adicionalmente, foram aplicados três índices de vulnerabilidade para os depósitos de sobrelavagem, conforme metodologia proposta por Garcia et al. (2010) – OSR, MOIR e CBO, e foram analisados os parâmetros granulométricos do sistema praia-duna atual e dos depositos de sobrelavagem em dois perfis transversais à barreira. A análise geomorfológica mostrou que as principais modificações observadas ao longo do tempo na BCI estiveram relacionadas à migração do canal de conexão da laguna com o oceano, anteriormente à sua fixação, bem como a eventos de sobrelavagem da barreira. Os depósitos de sobrelavagem apresentaram elevada frequência de ocorrência ao longo da barreira (OSR), onde a maior pôde ser observada no ano de 1957, atingindo 42% de todo o comprimento da barreira, em seu setor sul, e 60% no setor norte. Este padrão apresentou diminuição ao longo do tempo, e em 2012 cerca de 1% do comprimento do setor sul da barreira costeira apresentou sobrelavagem, enquanto o setor norte exibiu 19%. MOIR, índice referente às intrusões históricas de sobrelavagem e representando a recorrência de um máximo de intrusão, foi aplicado em intervalos de 10 metros e mostrou que eventos de transposição de sedimentos tendem a ocorrer todos os anos na área estudada, atingindo até 40 metros de intrusão. Para o ultimo ano de análise, 2012, o índice CBO apresentou três casos de valor máximo, indicando máxima vulnerabilidade de um rompimento da barreira costeira. No estudo comparativo entre os diferentes compartimentos do sistema praia-duna e dos depósitos de sobrelavagem não foi possível distinguir um claro padrão entre os subambientes com base nos parâmetros granulométricos. Entretanto, este padrão de não distinção pode indicar a usual influência de processos marinhos costeiros de sobrelavagem, atuantes sobre o sistema deposicional eólico. / The Itapocú coastal barrier is located in the northern coast of Santa Catarina State, on the domain of Barra Velha and Araquari cities. In its central part the barrier is segmented due to the influence of the Itapocú river mouth. Historical records demonstrate that the barrier experiments frequent overwash events. The barrier and associated environments were mapped for 1938, 1957, 1978, 2005 and 2012 dates. Additionally, three vulnerability indexes to the washover deposits were applied, according to Garcia et al. (2010) – OSR, MOIR and CBO, and the granulometric properties were analyzed for the modern beach-dune system and washover deposits in two cross sections. The morphological analysis showed that the main changes observed were related to inlet migration, before its fixation in 2011, and also to overwash events. The washover deposits showed high frequency of occurrence along the barrier (OSR), with the greater occurring in 1957, reaching 42% of its entire length in the south, and 60% in the north section. This pattern presented a decrease behavior over time, and in 2012 approximately 1% of the barrier length was overwashed in the south section and 19% in the north. The index MOIR, related to historical sediment intrusions of overwash processes, and representing a maximum intrusion was applied in 10m intervals and showed that washover events tend to occur in all years in the ICB, reaching 40m of intrusion. For the last year analyzed, 2012, the CBO index showed 3 situations of maximum intrusion, indicating 100% of barrier breaching vulnerability. In the comparative granulometric study, it was not possible to characterize the environmental deposits based on the granulometric parameters. However, non-discretize pattern can indicate the influence of coastal marine processes (overwash) acting over the eolian deposits.

Cette thèse présente l’étude de la signature sédimentaire des submersions marines de tempête, dans le domaine rétrolittoral. Cette signature peut être extrêmement variable principalement en fonction des paramètres météo-océaniques menant à la submersion, de la morphologie de l’avant-côte et du domaine rétrolittoral et du disponible sédimentaire. Premièrement, l’étude de dépôts de washover mis en place lors de l’hiver 2013-2014, au sud de l’île d’Oléron, particulièrement énergétique en terme de climat de vagues, via une approche couplant processus hydrodynamiques et sédimentologie, a permis (1) de mettre en évidence l’importance des ondes infragravitaires, sur une côte dissipative à caractère macrotidal, dans le déclenchement de l’overwash de la barrière et la mise en place de washovers ; et de (2) proposer un nouveau modèle de faciès des dépôts de washover mis en place par des ondes infragravitaires combinées à la marée haute. Deuxièmement, la caractérisation de la signature sédimentaire des submersions marines en domaine rétrolittoral plus distal a montré que dans le contexte morphologique des marais de Charente-Maritime, les apports extrêmement faibles de sédiments en provenance du domaine continental, entre deux évènements de submersion marine, empêche la distinction des différents niveaux de submersion. Cependant cette étude a permis de valider des proxies tels que la microfaune ou l’isotopie de la matière organique pour l’identification de niveaux de submersion marine, permettant en partie de pallier aux limites inhérentes à l’anomalie granulométrique généralement utilisée. Cette étude a aussi permis la mise en évidence d’une variabilité dans la signature sédimentaire des submersions marines entre deux marais géomorphologiquement contrastés et plus ou moins exposés aux houles en provenance de l’océan. / This thesis presents the study of the sedimentary signature of marine submersions triggered by storms, in the back barrier area. This signature can be extremely variable mainly according to the meteo-oceanic parameters leading to the submersion of the back barrier area, the morphology of the nearshore, shore and back barrier area, and sediment availability. Firstly, the study of washover deposits emplaced during the winter of 2013-2014 on the southern end of the Oléron Island, characterized by an exceptional wave climate, via a coupled hydrodynamical and sedimentological approach, allowed us to (1) highlight the importance of infragravity waves, on macrotidal and dissipative coasts, in triggering the overwash and emplace washover deposits ; and (2) to suggest a new facies model of washover deposits emplaced by infragravity waves combined to high tides. Secondly, the characterization of the sedimentary signature of marine submersions in the distal part of the back barrier area showed that in the morphological context of the Charente-Maritime coastal marshes, the extremely limited amounts of sediments in provenance from the continent, between two submersion events, prevent the distinction of the different marine submersion sedimentary layers. Nevertheless, this study allowed validating new proxies as microfauna and organic matter isotopy for the identification of marine submersion sedimentary signature, allowing to work independently of the granulometric anomaly proxy and its known limits. This study also allowed evidencing the variability in the sedimentary signature of marine submersions in geomorphologically contrasted marshes and that this variability was linked to the ocean waves exposure.

A detailed study of modern washover fan (fan) morphologies will clarify common fan geometries, lead to a better model for a “typical” fan, identify the preservation potential and probable geometries of fan facies in subsurface datasets and outcrops, and ultimately improve hydrocarbon recovery in barrier island reservoir systems. This study uses satellite imagery to conduct a spatial analysis of 118 modern fans to quantify geomorphologic attributes of fans. A new classification scheme for fans is proposed that refines the current fan model, dividing fans into channelized and non-channelized fans. Channelized fans are subdivided according to the location of primary deposition: barrier depo-center or lagoonal depo-center. Non-channelized fans are subdivided based on morphology: dissipative, lobate, or apron-sourced. Quantitative cross-plots of morphologic relationships are analyzed to define trends in fan morphologies. The most common type of fan encountered in our study is a non-channelized, line-sourced, lobate washover fan with an area of less than 1 km2 that is fully contained on a barrier and exhibits no subaqueous deposition in back-barrier waters. The Lower Cretaceous McMurray Formation is the primary reservoir of the Athabasca Oil Sands in Alberta, Canada. The upper McMurray is commonly interpreted as deposits of embayed coastal systems. Our location is in an under-studied area located 80 km northwest of Fort McMurray. Lateral and vertical facies changes, sedimentary structures, key surfaces, trace fossils, and bitumen saturation were documented in eight cores located along a 20 km transect situated paleo-landward of a Devonian paleo-high acting as a bedrock-barrier. Our data indicate that a flood tidal delta complex prograded landward into a back-barrier embayment through the stable, bedrock-controlled inlet. This system overlies middle McMurray fluvial sands and Devonian basement and was transgressed by marine waters prior to deposition of the overlying Wabiskaw Formation. Flood tidal delta sandbodies are bitumen saturated and therefore make good reservoirs; however, heavily bioturbated tidal flats can act as a barrier to flow where they encase flood tidal deltas, as encased sands were devoid of bitumen. This complex coastal paleogeography produced back-barrier deposits that contain a slightly more diverse, marine trace fossil assemblage than might otherwise be expected. / text

This study uses topographic profiles, washover fan volumes, and shoreline retreat rates to explore relationships between barrier types and Hurricane Harvey storm washover sedimentation. Pre- and post-Hurricane Harvey topographic profiles were created on 15 transects using Bare Earth LiDAR (2016) and surveyed elevations (2019). Depth and area of washover fan measurements were collected to estimate washover fan volumes. An inverse relationship was found between washover fan volume and pre- and post-storm barrier heights. Based on the topographic profiles, one section of shoreline had a scarp up to 3m high which blocked overwash, but appears to have increased shoreline erosion. In contrast, a low-lying section of shoreline generated relatively large washover fans, but experienced less shoreline retreat. Shoreline retreat was further quantified between 2014 and 2019 using Google Earth Imagery from 2014, 2016, 2017, and 2019 to track migration of the shoreline. The entire shoreline in the study area is undergoing relatively rapid retreat, but the results suggest that Hurricane Harvey increased erosional rates. The Colorado River Jetty borders the study area and may have acted as an anthropogenic barrier, likely reducing storm surge energy and contributing to marsh aggradation on transects in its close proximity. The study findings indicate that the identification and incorporation of other variables that influence washover magnitude would further the understanding of this complex natural system. The research results provide valuable information on the interaction of hurricane storm surge with natural and anthropogenic barriers, beach and dune erosion, and marsh aggradation along the coast of Texas.

published_or_final_version / Applied Geosciences / Master / Master of Science

This study uses the storm surge sediment beds deposited by Hurricanes Audrey (1957), Carla (1961), Rita (2005) and Ike (2008) to investigate spatial and temporal changes in sedimentation rates on the McFaddin National Wildlife Refuge in Southeast Texas. Fourteen sediment cores were collected along a transect extending from 90 to 1230 meters inland from the Gulf Coast. Storm-surge-deposited sediment beds were identified by texture, organic content, carbonate content, the presence of marine microfossils, and Cesium-137 dating. The hurricane-derived sediment beds are marker horizons that facilitate assessment of marsh sedimentation rates from nearshore to inland locations as well as over decadal to annual timescales. Near the shore, on a Hurricane Ike washover fan, where hurricane-derived sedimentation has increased elevation by up to 0.68 m since 2005, there was no measurable marsh sedimentation in the period 2008-2014. Farther inland, at lower elevations, sedimentation for the period 2008-2014 averaged 0.36 cm per year. The reduction in sedimentation in the period 2008-2014 on the nearshore part of the marsh is likely due to reduced flooding in response to increased elevation from hurricane storm surge sediment deposition. These results provide valuable knowledge about the sedimentary response of coastal marshes subject to storm surge deposition and useful guidance to public policy aimed at combating the effects of sea level rise on coastal marshes along the Gulf of Mexico.