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- CHSD Presentations (19)
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Articles 1 - 20 of 20
Full-Text Articles in Physical Sciences and Mathematics
Suspended Sediment Size Distribution In A Numerical Sediment Transport Model For A Partially-Mixed Estaury, Danielle Tarpley, Courtney Harris, Carl Friedrichs
Suspended Sediment Size Distribution In A Numerical Sediment Transport Model For A Partially-Mixed Estaury, Danielle Tarpley, Courtney Harris, Carl Friedrichs
Presentations
Particle settling velocity impacts the transport of suspended sediment to the first order but fine-grained material like muds tend to form loosely bound aggregates (flocs) whose settling velocity can vary widely. Properties of flocculated sediment such as settling velocity and particle density are difficult to predict because they change in response to several factors including salinity, suspended sediment concentration, turbulent mixing, and organic content. Knowledge of the mechanisms governing flocculation of cohesive sediment is rapidly expanding; especially in response to recent technical advances. As the understanding of particle dynamics progresses, numerical models describing flocculation and break-up are being developed with …
Fractal Floc Size, Density, Settling Velocity, And Implications For Water Clarity In Partially Mixed-Estuaries: The Role Of Small, Organic-Rich Particles, Kelsey Fall, Carl Friedrichs, Grace M. Massey, Jessie Turner
Fractal Floc Size, Density, Settling Velocity, And Implications For Water Clarity In Partially Mixed-Estuaries: The Role Of Small, Organic-Rich Particles, Kelsey Fall, Carl Friedrichs, Grace M. Massey, Jessie Turner
Presentations
Typical near-surface estuarine particles are not single solid particles, but clusters of inorganic and organic particles and water, called flocs. Floc properties that influence water clarity (such as size, composition, density and settling velocity) are challenging to observe in-situ, so their influence on the optical properties of the system is not well understood. The preliminary results presented here are part of a larger effort utilizing a combination of particle imaging equipment, water sampling, and optical instrumentation to measure important floc properties, to investigate the influence of organic particles and local hydrodynamics on those properties, and to evaluate the influence of …
Street-Level Inundation Modeling Of Hurricanes Matthew And Hermine And Emerging Flood Monitoring Methods In Hampton Roads, Jon Derek Loftis, H. V. Wang, D R. Forrest
Street-Level Inundation Modeling Of Hurricanes Matthew And Hermine And Emerging Flood Monitoring Methods In Hampton Roads, Jon Derek Loftis, H. V. Wang, D R. Forrest
Presentations
No abstract provided.
Fractal Floc Size, Settling Velocity And Implications For Water Clarity In Partially Mixed-Estuaries: The Role Of Small, Organic-Rich Particles, Kelsey Fall, Carl Friedrichs, Grace M. Cartwright, D.G. Bowers
Fractal Floc Size, Settling Velocity And Implications For Water Clarity In Partially Mixed-Estuaries: The Role Of Small, Organic-Rich Particles, Kelsey Fall, Carl Friedrichs, Grace M. Cartwright, D.G. Bowers
Presentations
Observations and analysis presented here suggest that properties of suspended particulate matter (SPM) in the water column of partially mixed estuaries, including floc size and settling velocity, are strongly related to the relative concentrations of inorganic versus organic matter in suspension. In regions with high inorganic SPM concentrations, addition of organic matter tends to increase the median size and settling velocity of flocs, removing both organic and inorganic SPM from the water column and enhancing water clarity relative to that in the absence of organics. In contrast, in regions with lower inorganic SPM concentration, suspended organic matter appears to decrease …
In Situ Differentiation Among Suspended Primary Particles, Resilient Pellets And Flocs Of Similar Size Using A Particle Image Camera System (Pics) In A Muddy Estuary, Grace M. Massey, Kelsey Fall, Carl Friedrichs, S.J. Smith
In Situ Differentiation Among Suspended Primary Particles, Resilient Pellets And Flocs Of Similar Size Using A Particle Image Camera System (Pics) In A Muddy Estuary, Grace M. Massey, Kelsey Fall, Carl Friedrichs, S.J. Smith
Presentations
No abstract provided.
Relationships Among Estuarine Floc Size, Optical Properties, Organic Content, And Settling Velocity: Insights Gained From Combining Lisst And A Particle Imaging Camera System, Kelsey Fall, Carl Friedrichs, Grace M. Cartwright, D.G. Bowers
Relationships Among Estuarine Floc Size, Optical Properties, Organic Content, And Settling Velocity: Insights Gained From Combining Lisst And A Particle Imaging Camera System, Kelsey Fall, Carl Friedrichs, Grace M. Cartwright, D.G. Bowers
Presentations
No abstract provided.
Self-Burial Of Objects On Sandy Beds By Wave- And Current-Induced Scour, Carl Friedrichs, S.E. Rennie, A. Brandt
Self-Burial Of Objects On Sandy Beds By Wave- And Current-Induced Scour, Carl Friedrichs, S.E. Rennie, A. Brandt
Presentations
When an object sitting on the bed extends above the surrounding bed roughness, the object will alter the local flow pattern relative to the far field boundary layer. Such perturbations increase the velocities and stresses impinging on sediment immediately adjacent to the object. Nearby grains tend to be dispersed, resulting in a scour pit that deepens until the tendency for sediment to be dispersed is balanced by a tendency for sediment to fall back into the pit. The difference in pressure at the bed upstream and downstream of the object may also drive seepage flow which can cause piping and …
Comt Chesapeake Bay Hypoxia Modeling, M.A.M. Friedrichs, Carl T. Friedrichs, M. Scully, I. Irby, Comt Estaurine Hypoxia Team
Comt Chesapeake Bay Hypoxia Modeling, M.A.M. Friedrichs, Carl T. Friedrichs, M. Scully, I. Irby, Comt Estaurine Hypoxia Team
Presentations
No abstract provided.
Comparison Of Modeled And Observed Bed Erodibility In The York River Estuary, Virginia, Over Varying Time Scale, Danielle Tarpley, Courtney Harris, Carl Friedrichs
Comparison Of Modeled And Observed Bed Erodibility In The York River Estuary, Virginia, Over Varying Time Scale, Danielle Tarpley, Courtney Harris, Carl Friedrichs
Presentations
In general, the availability of sediment for transport increases with the magnitude of bed shear stress, which varies over various temporal and spatial scales. However, in a muddy setting, consolidation or swelling of the bed also contributes to fluctuations in sediment mobility. One such environment is the York River estuary, a partiallymixed tidal tributary of the Chesapeake Bay, USA. The York River often has a Secondary Turbidity Maximum (STM) mid-estuary at the transition from a shallower, less stratified section upstream to a deeper, more stratified section downstream. Since 2006 various instrument arrays have been deployed as part of the Multidisciplinary …
Us-Ioos/Comt Estuarine Hypoxia Nowcast/Forecast Product: Identification And Feedback, Carl T. Friedrichs, Marjorie A.M. Friedrichs, David R. Forrest, R.R. Hood
Us-Ioos/Comt Estuarine Hypoxia Nowcast/Forecast Product: Identification And Feedback, Carl T. Friedrichs, Marjorie A.M. Friedrichs, David R. Forrest, R.R. Hood
Presentations
The Estuarine Hypoxia component of the U.S. Integrated Ocean Observing System (US-IOOS) Coastal and Ocean Modeling Testbed (COMT) is evaluating existing hydrodynamic and water quality models used or likely to be used for operations and/or for regulation in the Chesapeake Bay and other, similar estuarine environments. The outcomes of this work are expected to help with the development of operational hypoxia forecast capabilities for the Bay. As a proof-of-concept, the ChesROMS hydrodynamic model, linked to a 1-term constant respiration equation for dissolved oxygen (DO), is presently being used to produce realtime now-casts and shortterm (3-day) forecasts of DO for the …
Consolidation And Stratification Within A Muddy, Partially Mixed Estuary: A Comparison Between Idealized And Realistic Models For Sediment Transport In The York River Estuary, Virginia, Danielle Tarpley, Courtney Harris, Carl Friedrichs
Consolidation And Stratification Within A Muddy, Partially Mixed Estuary: A Comparison Between Idealized And Realistic Models For Sediment Transport In The York River Estuary, Virginia, Danielle Tarpley, Courtney Harris, Carl Friedrichs
Presentations
The York River estuary is a partially mixed semi-diurnal tidal tributary of the Chesapeake Bay with salinities ranging from 0 to 26 psu and an ~0.8 m tidal range. Sediment within many estuaries, including the York River, Virginia, is dominated by mixtures of mud. Due to its cohesive nature, estimating sediment fluxes for mud is a complex problem that can be addressed using numerical models such as the Community Sediment Transport Modeling System (CSTMS), which incorporates suspended sediment transport, erosion, and deposition within the hydrodynamic Regional Ocean Modeling System (ROMS). One version of the CSTMS accounts for cohesive processes via …
Identification Of Suspended Resilient Pellets In Particles Tracked By A Particle Image Camera System (Pics) In A Muddy Estuary, Grace M. Massey, Kelsey Fall, Carl Friedrichs, S.J. Smith
Identification Of Suspended Resilient Pellets In Particles Tracked By A Particle Image Camera System (Pics) In A Muddy Estuary, Grace M. Massey, Kelsey Fall, Carl Friedrichs, S.J. Smith
Presentations
No abstract provided.
Hypoxia Forecasts As A Tool For Chesapeake Bay Fisheries, Marjorie A.M. Friedrichs, Carl T. Friedrichs, David R. Forrest, R.R. Hood
Hypoxia Forecasts As A Tool For Chesapeake Bay Fisheries, Marjorie A.M. Friedrichs, Carl T. Friedrichs, David R. Forrest, R.R. Hood
Presentations
No abstract provided.
Examining Spring-Neap Cycle Variation In Bed Erodibility In The York River Estuary, Va: A Numerical Study, Danielle Tarpley, Courtney Harris, Carl Friedrichs
Examining Spring-Neap Cycle Variation In Bed Erodibility In The York River Estuary, Va: A Numerical Study, Danielle Tarpley, Courtney Harris, Carl Friedrichs
Presentations
The York River estuary is categorized as micro-tidal with a tidal range ~0.8 m; however, periodically produce enough shear stress to erode sediment from the bed and redistribute it along the estuary. However, the supply of mobile sediment differs over various temporal and spatial scales. The primary focus here is to examine the tidal variation in bed mobility by comparing variations in bed erodibility over the spring-neap cycle. To accomplish this goal, the Community Sediment Transport Modeling System (CSTMS) is implemented in a three-dimensional domain using the Regional Ocean Modeling System (ROMS). This version of the CSTMS accounts for suspended …
Influence Of Suspended Particle Properties On Optical Properties And Resultant Water Clarity Along A Partially-Mixed Estuary, York River, Virginia, Usa, Kelsey Fall, Carl Friedrichs, Grace M. Cartwright, David Bowers
Influence Of Suspended Particle Properties On Optical Properties And Resultant Water Clarity Along A Partially-Mixed Estuary, York River, Virginia, Usa, Kelsey Fall, Carl Friedrichs, Grace M. Cartwright, David Bowers
Presentations
The Chesapeake Bay and its associated tidal tributaries are among the many coastal systems where degraded water clarity is a major concern. Despite long-term decreases in sediment input, water clarity has continued to deteriorate, especially in the southern Bay. Here it is proposed that the disconnect between water clarity and sediment input is related to the dynamic nature of locally suspended estuarine particles, as well as the interaction between suspended organic particles and inorganic solids. Typical estuarine particles are not single solid particles, but clusters of inorganic and organic particles and water (i.e., flocs). Floc properties (such as size, composition, …
What Controls Bed Erodibility In Muddy, Partially-Mixed Estuaries? Insights From The York River, Virginia, Carl Friedrichs, Grace M. Cartwright, P.J. Dickhudt, Kelsey Fall
What Controls Bed Erodibility In Muddy, Partially-Mixed Estuaries? Insights From The York River, Virginia, Carl Friedrichs, Grace M. Cartwright, P.J. Dickhudt, Kelsey Fall
Presentations
Appropriate parameterization of time-dependent erodibility of muddy seabeds is a significant barrier to improved understanding and accurate modeling of sediment dynamics in estuaries and other coastal regions. In an effort to better understand controls on muddy seabed erodibility, bed erodibility and associated bed sediment properties have been measured by our group on cores collected on dozens of cruises over the last decade in the York Estuary. We have also inferred time-varying erodibility indirectly in the York Estuary over several years by vertically integrating observations of tidally-varying suspended sediment concentration. This presentation synthesizes the results of these long-term observations in this …
Controls On Suspended Particle Properties And Water Clarity Along A Partially-Mixed Estuary, York River, Virginia, Kelsey Fall, Carl Friedrichs, Grace M. Cartwright, David Bowers
Controls On Suspended Particle Properties And Water Clarity Along A Partially-Mixed Estuary, York River, Virginia, Kelsey Fall, Carl Friedrichs, Grace M. Cartwright, David Bowers
Presentations
The Chesapeake Bay and its associated tidal tributaries, which together form one of the United States’ largest and most important estuaries, are among the many coastal systems where degraded water clarity is a major concern. Despite long-term decreases in sediment input, water clarity has continued to deteriorate in the southern Bay. Paradoxically, clarity has declined less in the northern Bay where riverine sediment load has recently increased. Here it is proposed that the disconnect between water clarity and sediment input is related to the dynamic nature of locally suspended estuarine particles, as well as the interaction between suspended organic particles …
What Controls Bed Erodibility In Muddy, Partially-Mixed Estuaries? Insights From The York River, Virginia, Carl Friedrichs, Grace M. Cartwright, P.J. Dickhudt, Kelsey Fall
What Controls Bed Erodibility In Muddy, Partially-Mixed Estuaries? Insights From The York River, Virginia, Carl Friedrichs, Grace M. Cartwright, P.J. Dickhudt, Kelsey Fall
Presentations
Appropriate parameterization of time-dependent erodibility of muddy seabeds is a significant barrier to improved understanding and accurate modeling of sediment dynamics in estuaries and other coastal regions. In an effort to better understand controls on muddy seabed erodibility, bed erodibility and associated bed sediment properties have been measured by our group on cores collected on dozens of cruises over the last decade in the York Estuary. We have also inferred time-varying erodibility indirectly in the York Estuary over several years by vertically integrating observations of tidally-varying suspended sediment concentration. This presentation synthesizes the results of these long-term observations in this …
Evaluating The Effects Of Cohesive Processes On Sediment Distribution In An Idealized, Partially-Mixed Estuary Using A Numerical Model, Danielle Tarpley, Courtney Harris, Carl Friedrichs
Evaluating The Effects Of Cohesive Processes On Sediment Distribution In An Idealized, Partially-Mixed Estuary Using A Numerical Model, Danielle Tarpley, Courtney Harris, Carl Friedrichs
Presentations
An idealized two-dimensional model is designed to represent a longitudinal section of a partially-mixed estuary, accounting for a freshwater source, tides, and estuarine circulation, but neglecting across-channel variations. The Community Sediment Transport Modeling System (CSTMS) is used to simulate suspended transport, erosion, and deposition within the Regional Ocean Modeling System (ROMS). This version of the model also includes cohesive processes such as consolidation and swelling of the sediment bed; sediment-induced stratification; and variable settling velocities. To better understand the processes controlling fine-grained sediment transport in the York River, VA, the primary features of the idealized estuary mimic that system, and …
Challenges Associated With Modeling Low-Oxygen Waters In Chesapeake Bay: A Multiple Model Comparison, I.D. Irby, M. A.M. Friedrichs, Carl T. Friedrichs, Comt Estuarine Hypoxia Team
Challenges Associated With Modeling Low-Oxygen Waters In Chesapeake Bay: A Multiple Model Comparison, I.D. Irby, M. A.M. Friedrichs, Carl T. Friedrichs, Comt Estuarine Hypoxia Team
Presentations
As ecosystem and water quality models are becoming more frequently used for operational forecasts and scenario-based management decisions, it is important to understand the relative strengths and limitations of existing models of varying complexity. To this end, simulations of the Chesapeake Bay from eight threedimensional coupled hydrodynamic-oxygen models have been statistically compared to each other and to two years of historical monitoring data. Results show that although models have difficulty resolving the variables typically thought to be the main drivers of dissolved oxygen variability (stratification, nutrients, and chlorophyll), all eight models have significant skill in reproducing the mean and seasonal …