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Full-Text Articles in Physical Sciences and Mathematics
Importance Of Muddy Bed Aggregate Processes In Cohesive Sediment Dynamics Associated With Sediment Management Projects, David Perkey
Importance Of Muddy Bed Aggregate Processes In Cohesive Sediment Dynamics Associated With Sediment Management Projects, David Perkey
Dissertations, Theses, and Masters Projects
The erosion and transport processes of fine sediment is largely impacted by the aggregation state. Understanding fine sediment transport processes is a key component to managing the nation’s navigation channels, ports, and reservoirs. To improve its ability to apply management strategies related to fine sediments, the USACE has undertaken research that focusses on the aggregation state of fine sediment. Of particular interest is the ability to expand the use of fine-grained sediment in projects that seek to beneficially use dredge material. In this study, a newly developed camera system was used to evaluate the aggregation state of eroded sediment from …
Barrier-Island Dynamics: Transgression, Regression, And State Changes, Justin Lee Shawler
Barrier-Island Dynamics: Transgression, Regression, And State Changes, Justin Lee Shawler
Dissertations, Theses, and Masters Projects
Barrier islands provide critical habitat for shorebirds and buffer backbarrier and inland coastal habitats and communities from the direct effects of storms and wave energy. Yet, barrier systems are under threat from these very same processes. In particular, whereas long-term barrier behavior and landward migration rate is directly related to the rate of sea-level rise, decadal to centennial barrier-island dynamics are more complicated, and often highly localized. Barrier-island dynamics—including state changes between seaward growth and landward migration—are driven by a complex interplay of forcings and interactions, including changes in longshore and cross-shore sediment fluxes, underlying geology and slope, barrier-marsh and …
Water Clarity And Suspended Particle Dynamics In The Chesapeake Bay: Local Effects Of Oyster Aquaculture, Regional Effects Of Reduced Shoreline Erosion, And Long-Term Trends In Remotely Sensed Reflectance, Jessica Turner
Dissertations, Theses, and Masters Projects
Water clarity is a key indicator of the ecosystem health in the Chesapeake Bay. Estuarine water clarity fluctuates due to external inputs from the watershed as well as processes occurring within the estuary itself, such as sediment resuspension and organic matter production. Therefore, water clarity requires study at multiple spatial and temporal scales and with multiple metrics. One local-scale process potentially influencing water clarity is shellfish aquaculture. One part of this dissertation examined how water quality and hydrodynamics varied among oyster farms as well as inside versus outside the extent of caged areas located in southern Chesapeake Bay. Current speed …
Controls On Estuarine Sediment Bed Erodibility: Insights From The York River Estuary, Cristin Lee Wright
Controls On Estuarine Sediment Bed Erodibility: Insights From The York River Estuary, Cristin Lee Wright
Dissertations, Theses, and Masters Projects
The erodibility of estuarine sediment beds has a number of ecological and societal implications, including alteration of benthic habitats, light-limitation of primary production, and reintroduction of pollutants to the water column, as well as impacts on dredging operations and on the fate of potentially dangerous objects on the seafloor. The objectives of this study are to better understand controls on bed erodibility in estuarine environments, including the roles of sediment grain size, water content, percent organics, and bed fabric, as well as effects of tides, storms, salinity distribution, river discharge, and location within the estuary. An extensive set of erosion …
Sediment And Terrestrial Organic Carbon Budgets For The Offshore Ayeyarwady Delta: Establishing A Baseline For Future Change, Evan Rose Flynn
Sediment And Terrestrial Organic Carbon Budgets For The Offshore Ayeyarwady Delta: Establishing A Baseline For Future Change, Evan Rose Flynn
Dissertations, Theses, and Masters Projects
Large river deltas serve as globally important archives of terrestrial and shallow marine biogeochemical signatures because of rapid sediment burial, and have the potential to impact global biogeochemical cycling on modern and geologic timescales. This study investigates modern sediment and terrestrial organic carbon (TerrOC) accumulation within the offshore Ayeyarwady Delta in order to determine sediment and TerrOC budgets for this largely understudied mega-delta. The Ayeyarwady is the world’s third largest delta in terms of sediment supply, and remains one of the last long free-flowing rivers in Asia. However, recent increases in regional anthropogenic impacts risk severe alterations to sediment and …
Assessment Of The High-Resolution Sediment Gravity Flow Record In Prince William Sound, Alaska, Elisabeth Rose Clyne
Assessment Of The High-Resolution Sediment Gravity Flow Record In Prince William Sound, Alaska, Elisabeth Rose Clyne
Dissertations, Theses, and Masters Projects
South-Central Alaska is one of the most seismically active and climatologically sensitive places in the world. Within this region, Prince William Sound (PWS) receives abundant sediment from multiple sources, potentially housing a high-resolution environmental record spanning the past 4,000 years. Inputs to PWS are derived from local rivers and glaciers, and may include earthquake- and glacial-outburst-triggered sediment gravity flows. Therefore, this is an ideal location to investigate the long-term record of seismic, glacial, and riverine activity. This study examines the elemental, grain size, and stable isotope signatures in PWS to identify gravity flow deposits and the potential paleoseismic and paleoclimate …
Reconstructing Coastal Forest Retreat And Marsh Migration Response To Historical Sea Level Rise, Nathalie Schieder
Reconstructing Coastal Forest Retreat And Marsh Migration Response To Historical Sea Level Rise, Nathalie Schieder
Dissertations, Theses, and Masters Projects
Climate change assessments predict that rates of relative sea level rise will increase in the future, leading to enhanced inundation of low-lying coastal regions and a 20 – 50 % decline in salt marsh area by 2100. Global sea level rise began accelerating in the late 19th to early 20th century, and local rates along the U.S. mid-Atlantic coast are twice as fast as global estimates. Frequent flooding and salt stress associated with sea level rise lead to coastal transgression, and the survival of ecosystems depends on their ability to migrate inland faster than they erode and submerge. Here, I …
Signature Of Recent Sediment Accumulating In Prince William Sound, Alaska: A Record Of Storms, Earthquakes, And Seasonal Inputs, Nicole R. Marshall
Signature Of Recent Sediment Accumulating In Prince William Sound, Alaska: A Record Of Storms, Earthquakes, And Seasonal Inputs, Nicole R. Marshall
Dissertations, Theses, and Masters Projects
This study focuses on the development o f provenance signatures for sediments accumulating in Prince William Sound, with an emphasis on interpreting mechanisms of sediment deposition using historical earthquake, wave, river discharge, and glacial outburst flood records. A highresolution sedimentary sequence in Prince William Sound, Alaska contains sediments sourced from local watersheds as a result of seasonal and event-driven sedimentation. This study contributes to the development of paleo-proxies for sediment provenance, earthquakes, shelf sediment resuspension, and Copper River discharge. Geochemical studies of sediment cores and end-member samples using X-ray fluorescence and inductively coupled plasma mass spectrometry allows for the development …
Sediment Deposition And Reworking: A Modeling Study Using Isotopically Tagged Sediment Classes, Justin J. Birchler
Sediment Deposition And Reworking: A Modeling Study Using Isotopically Tagged Sediment Classes, Justin J. Birchler
Dissertations, Theses, and Masters Projects
A sediment transport model within the Regional Ocean Modeling System (ROMS) was used to examine how repeated cycles of deposition, erosion, and bioturbation influence flood and storm event bed character offshore of a significant fluvial source. Short-lived radioisotopes Beryllium-7 (7Be) and Thorium-234 (234Th) can be used as tracers of deposition and reworking on the continental shelf, and modeled profiles of these radioisotopes, along with simulated profiles of sediment bed grain size distributions, were analyzed for various model runs.The presence of an atmospherically derived radionuclide,7Be, in seafloor sedimentindicates terrestrial (riverine derived) sediment deposition offshore of a fluvial source.In contrast,234Th naturally occurs …
High-Resolution Sediment Records Of Seismicity And Seasonal Sedimentation From Prince William Sound, Alaska, Using Xrf Core Scanning, Eric J. Miller
High-Resolution Sediment Records Of Seismicity And Seasonal Sedimentation From Prince William Sound, Alaska, Using Xrf Core Scanning, Eric J. Miller
Dissertations, Theses, and Masters Projects
The southern coast of Alaska is a climatically sensitive and tectonically active region, however due to its remoteness and harsh climate there are limited long-term historical records of environmental conditions such as storm frequency, river discharge, and earthquakes. In order to determine the potential for Prince William Sound sediments to contain high-resolution paleorecords of these conditions, a suite of 11 gravity cores was collected within the Sound in order to determine the modern day sediment depositional trends and to develop elemental proxies for earthquakes and seasonal sedimentation. 210Pb/137Cs-derived sedimentation rates and grain size trends indicate that there are two distinct …
Application Of Acoustics And Optics For The Characterization Of Suspended Particulate Matter Within An Estuarine Observing System, Grace M. Cartwright
Application Of Acoustics And Optics For The Characterization Of Suspended Particulate Matter Within An Estuarine Observing System, Grace M. Cartwright
Dissertations, Theses, and Masters Projects
As part of this dissertation work, a long term observing station at Clay Bank on the York River in Virginia has been established and maintained since 2006, and was used to gain a better understanding of sediment processes in a muddy estuary and in muddy coastal environments in general. While data from this NSF-funded Multi-Disciplinary Benthic Exchange Dynamic (MUDBED) observing system has and will be used by other students for this general purpose, this dissertation focuses specifically on better understanding and interpretation of the data collected by key instrumentation regularly deployed at the observing station, especially the acoustic Doppler velocimeter …
Acoustic And Sedimentological Investigations Of Seabed Conditions And Related Bio-Geological Parameters In A Tidally Energetic, Fine-Grained Environment: York River Estuary, Virginia, Lindsey M. Kraatz
Dissertations, Theses, and Masters Projects
The transport and fate of fine-grained sediments is a critical factor affecting the physical, chemical, and biological health of estuaries, coastal embayments, riverine, lacustrine, and continental shelf environments. A geophysical and sedimentological study of the York River as a part of the NSF Multi-disciplinary Benthic Exchange Dynamics (MUDBED) project was conducted to determine: 1) the primary drivers of sediment erodibility within a fine-grained system, 2) if these drivers can be accurately measured through sedimentological and acoustic information, and 3) the spatial and seasonal variability of erosion within the estuary. Previous studies indicate that increased erodibility within the York River Estuary …
Holocene Sedimentation On The Lanyang Plain And Adjacent Continental Shelf, Northwestern Taiwan, Chia-Yu Wu
Holocene Sedimentation On The Lanyang Plain And Adjacent Continental Shelf, Northwestern Taiwan, Chia-Yu Wu
Dissertations, Theses, and Masters Projects
The Lanyang Plain, along the northeastern Taiwan orogen, provides an excellent example of the tectonic and climatic controls on erosion and subsequent riverine sediment supply to the coastal ocean and deep sea. 12 deep borings on the Lanyang Plain and 2 long cores in Southern Okinawa Trough (MD12403, ODP1202), together with high-resolution seismic data on Ilan Shelf, provide a good record of the depositional history during Holocene, in both on-land and offshore areas. Based on these data, we find the sediment thickness reaches 216 m in Lanyang Plain, and the average sediment rate is estimated to be 3.6 Mt/yr - …
Integrating Space-And Time-Scales Of Sediment-Transport For Poverty Bay, New Zealand, Aaron J. Bever
Integrating Space-And Time-Scales Of Sediment-Transport For Poverty Bay, New Zealand, Aaron J. Bever
Dissertations, Theses, and Masters Projects
Poverty Bay is a small embayment located in the middle of the Waipaoa River Sedimentary Dispersal System (WSS) on the eastern coast of the north island of New Zealand. Within this dispersal system, a large multidisciplinary study was focused on determining the sediment routing from the source within the headwaters to the locations of sediment accumulation on the continental shelf and slope. Poverty Bay acts as the land to sea transition area in the WSS, and as such significantly modifies the fluvial sedimentary signal before it is exported to the continental shelf. Until this study, little hydrodynamic or sediment-transport work …
Observations Of Storm Morphodynamics Using Coastal Lidar And Radar Imaging System (Claris): Importance Of Wave Refraction And Dissipation Over Complex Surf-Zone Morphology At A Shoreline Erosional Hotspot, Katherine L. Brodie
Dissertations, Theses, and Masters Projects
Elevated water levels and large waves during storms cause beach erosion, overwash, and coastal flooding, particularly along barrier island coastlines. While predictions of storm tracks have greatly improved over the last decade, predictions of maximum water levels and variations in the extent of damage along a coastline need improvement. In particular, physics based models still cannot explain why some regions along a relatively straight coastline may experience significant erosion and overwash during a storm, while nearby locations remain seemingly unchanged. Correct predictions of both the timing of erosion and variations in the magnitude of erosion along the coast will be …
Controls On Continental Shelf Stratigraphy: Waiapu River, New Zealand, Heidi M. Wadman
Controls On Continental Shelf Stratigraphy: Waiapu River, New Zealand, Heidi M. Wadman
Dissertations, Theses, and Masters Projects
A quantitative understanding of the processes controlling sediment transport and deposition across the land/sea interface is crucial to linking terrestrial and marine environments and understanding the formation of marine stratigraphy. The nature and distribution of terrestrial-derived sediment preserved in shelf stratigraphy in turn provides insight into the complex linkages inherent in source-to-sink sediment dynamics. Located inboard of an actively subducting plate boundary and characterized by one of the highest sediment yields in the world, the open-shelf setting off of the Waiapu River in New Zealand presents an excellent location to improve our understanding of the factors controlling the formation of …
Nearshore Morphology And Lithology: Links To Framework Geology And Shoreline Change, Jennifer L. Miselis
Nearshore Morphology And Lithology: Links To Framework Geology And Shoreline Change, Jennifer L. Miselis
Dissertations, Theses, and Masters Projects
Despite evidence of the geologic and morphologic complexity of inner shelves worldwide, there is a paucity of observations from the nearshore, inhibiting direct comparison of these factors to coastal change. Using geophysical instruments to characterize the geology of the nearshore, this research focuses on the relationships between nearshore stratigraphy, sediment heterogeneity, shoreface morphology and shoreline behavior. While generally not considered in engineering models of shoreline evolution, these factors influence nearshore processes. Overall, the findings presented highlight the importance of nearshore geology, both at the seafloor and underlying it, in contributing to modem sediment transport processes affecting beaches. Shallow, sub-seafloor geology …
A Modern Sediment Budget For The Continental Shelf Off The Waipaoa River, New Zealand, Andrea J. Miller
A Modern Sediment Budget For The Continental Shelf Off The Waipaoa River, New Zealand, Andrea J. Miller
Dissertations, Theses, and Masters Projects
No abstract provided.
Recent Sedimentation Patterns And Facies Distribution On The Waipaoa River Shelf, N.Z, Lila Eve Rose
Recent Sedimentation Patterns And Facies Distribution On The Waipaoa River Shelf, N.Z, Lila Eve Rose
Dissertations, Theses, and Masters Projects
No abstract provided.
Shelf Sediment Dispersal Mechanisms And Deposition On The Waiapu River Shelf, New Zealand, Tara A. Kniskern
Shelf Sediment Dispersal Mechanisms And Deposition On The Waiapu River Shelf, New Zealand, Tara A. Kniskern
Dissertations, Theses, and Masters Projects
The Waiapu River, located on the North Island of New Zealand, drains a small catchment and has one of the highest sediment yields in the world. The river delivers most of its annual sediment load during floods into energetic coastal waters. These conditions are favorable for producing multiple sediment transport mechanisms, including transport in positively and negatively buoyant freshwater plumes, gravitydriven flows, and resuspension. Analyses of Waiapu River shelf seabed data showed that multiple transport mechanisms influence strata formation. Fluvial sediments are initially deposited at water depths shallower than 80 m before being remobilized and deposited at greater water depths. …
Linking Land To Ocean: Flux And Fate Of Water And Sediment From The Yangtze River To The East China Sea, Kehui Xu
Dissertations, Theses, and Masters Projects
Although precipitation and runoff for the entire Yangtze River watershed have changed little since 1950, the increase of runoff in Yangtze southern sub-basin has been much larger than that of precipitation, reflecting decreased temperatures and evapotranspiration, In contrast, the marked decreases in runoff in northern Yangtze have been due mainly to increased water consumption. Since the 1980s, the Yangtze sediment load has declined dramatically, and 2004 loads at Yichang (just below the Three Gorges Dam - TGD) and Datong (lower stream) were only 12% and 33% of those in the 1950s and 60s, reflecting precipitation decline, landuse change, and most …
Assessing Anthropogenic And Natural Impacts On Ghost Crab ( Ocypode Quadrata) Populations At Cape Hatteras National Seashore, North Carolina, Cynthia B. Landry
Assessing Anthropogenic And Natural Impacts On Ghost Crab ( Ocypode Quadrata) Populations At Cape Hatteras National Seashore, North Carolina, Cynthia B. Landry
Dissertations, Theses, and Masters Projects
No abstract provided.
Controls On The Delivery Of Fluvial Sediment To The Coastal Ocean: The Salinas River, California, Katherine L. Farnsworth
Controls On The Delivery Of Fluvial Sediment To The Coastal Ocean: The Salinas River, California, Katherine L. Farnsworth
Dissertations, Theses, and Masters Projects
To estimate delivery to the coastal ocean, a global river database was assembled. An estimated 35,000 km3 of freshwater, 4 * 10 6 tonnes of dissolved solids and 18.6 * 106 tonnes of suspended sediment are delivered annually. The global delivery of fluvial water and sediment, both suspended and dissolved, is dominated by Southeast Asia, due to the unique climatic, geologic and geomorphic character of the rivers in this region. Over 30% of the global freshwater and dissolved solid discharge, and an astounding 70% of the suspended sediment originate in this region. The Salinas River, central California, was the focus …
Post-Glacial Sedimentation In A River -Dominated Epicontinental Shelf: The Yellow Sea Example, Jing-Pu Liu
Post-Glacial Sedimentation In A River -Dominated Epicontinental Shelf: The Yellow Sea Example, Jing-Pu Liu
Dissertations, Theses, and Masters Projects
The North Yellow Sea (NYS) and South Yellow Sea (SYS), stretching from the Bohai Sea in the north to the East China Sea (ECS) in the south, represents an end member of modern epicontinental seas. Because of its shallow depths, the Yellow Sea was entirely exposed subaerially during the last glacial maximum. The new post-glacial sea-level curve derived from an extensive local dataset shows a series of rapid flooding events (12--45 mm/y), separated by a series of slow rises (2--6 mm/y). By about 15 ka, sea level had reached -100 m, and seawater entered the SYS. A rapid rise during …
Modeling Of Critically-Stratified Gravity Flows: Application To The Eel River Continental Shelf, Northern California, Malcolm E. Scully
Modeling Of Critically-Stratified Gravity Flows: Application To The Eel River Continental Shelf, Northern California, Malcolm E. Scully
Dissertations, Theses, and Masters Projects
An analytical and numerical model are presented and applied to predict gravitydriven transport and deposition of fluid mud layers that form within the wave boundary layer on the continental shelf off the Eel River in northern California. Observations indicate that following floods of the Eel River down-slope transport of fluid mud trapped within the wave boundary layer is the dominant across-shelf transport mechanism. The models are based upon the assumption that following significant floods, an abundant supply of easily suspended fine sediment is delivered to the coastal ocean, allowing a negative feedback mechanism to maintain the near-bed Richardson number at …
Fine-Scale Strata Formation In Biologically And Physically Dominated Estuarine Systems Within The Lower Chesapeake And York River Subestuary, Timothy M. Dellapenna
Fine-Scale Strata Formation In Biologically And Physically Dominated Estuarine Systems Within The Lower Chesapeake And York River Subestuary, Timothy M. Dellapenna
Dissertations, Theses, and Masters Projects
To investigate the relationship between biological and physical mixing in forming strata, the lower mainstem of Chesapeake Bay has been contrasted with the York River Subestuary. By using radioisotope profiles from sediment cores, comparisons are made in terms of depth and rate of sediment mixing, deposition and accretion. Within the lower Chesapeake Bay two sites were selected as biologically dominated, both are located within the bay stem plains and are characterized by muddy sand and an abundance of large, deep-dwelling organisms. X-radiographs indicate complete biological reworking of sediments. 210Pb profiles reveal low sediment accretion rates within the mainstem sites ( …
Sediment Dispersal And Sequence Development Along A Tectonically Active Margin: Late Quaternary Evolution Of The Ganges-Brahmaputra River Delta, Steven Lee Goodbred Jr.
Sediment Dispersal And Sequence Development Along A Tectonically Active Margin: Late Quaternary Evolution Of The Ganges-Brahmaputra River Delta, Steven Lee Goodbred Jr.
Dissertations, Theses, and Masters Projects
Situated in the Bengal Basin, the Ganges-Brahmaputra river delta comprises one of the largest fluviodeltaic systems in the world, comprising ∼ 100,000 km2 of floodplain and delta plain and a 40,000 km2 subaqueous delta on the shelf. Sediment load of the Ganges-Brahmaputra river is 109 t/yr, and seasonal flooding may inundate >70% of the delta during large events. Active tectonic processes have resulted in both uplift and subsidence in this structurally complex region. These general characteristics suggest that the Ganges-Brahmaputra delta represents a heretofore undescribed delta end-member, forming along a high-yield, high-energy, tectonically active margin. to investigate this view, stratigraphic, …
Spatial, Geostatistical, And Fractal Measures Of Seafloor Microtopography Across The Eel River Shelf, Off Northern California, George Randall. Cutter
Spatial, Geostatistical, And Fractal Measures Of Seafloor Microtopography Across The Eel River Shelf, Off Northern California, George Randall. Cutter
Dissertations, Theses, and Masters Projects
No abstract provided.
Modeling Storm-Induced Sediment Transport On The Inner Shelf: Effects Of Bed Microstratigraphy, Baeck Oon Kim
Modeling Storm-Induced Sediment Transport On The Inner Shelf: Effects Of Bed Microstratigraphy, Baeck Oon Kim
Dissertations, Theses, and Masters Projects
Sediment transport during a storm event on the inner continental shelf was detailed through the development of models based on field experiments conducted at Duck, North Carolina in October 1994. A vertical one-dimensional model (1DV model) was developed by coupling the Grant and Madsen (1986) model with bed stratigraphy to consider real seabeds. Sediment was divided into seven size classes and fractional transport was estimated. Mixing depth and total depth from a simplified sediment conservation equation provided the basis for changing bottom sediment, sediment availability for transport, and armoring processes. These processes involve a feedback between hydrodynamics and bed stratigraphy. …
High-Resolution Seismic Stratigraphy Of The Ganges-Brahmaputra River System: Subaqueous Deltaic Progradation On The Bengal Shelf, Beth Michele Levy
High-Resolution Seismic Stratigraphy Of The Ganges-Brahmaputra River System: Subaqueous Deltaic Progradation On The Bengal Shelf, Beth Michele Levy
Dissertations, Theses, and Masters Projects
No abstract provided.