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Portland State University

Sediment transport

Civil and Environmental Engineering Faculty Publications and Presentations

Publication Year

Articles 1 - 4 of 4

Full-Text Articles in Engineering

Circulation, Sediment Concentration And Oxygen Depletion In The Tidal Ems River, Stefan A. Talke, Huib E. De Swart Jan 2011

Circulation, Sediment Concentration And Oxygen Depletion In The Tidal Ems River, Stefan A. Talke, Huib E. De Swart

Civil and Environmental Engineering Faculty Publications and Presentations

We present measurements which show that the tidal Ems River in Germ any is extremely muddy over a 30 km + turbid zone, with fluid mud o f 1-2 m thickness covering the bed with suspended sediment concentrations (SSC) o f greater than 50 kg.m-3. Moreover, we show that these elevated SSC contain large quantities of organic material which deplete dissolved oxygen (DO) and produce summertime hypoxic zones. Using mathematical modeling, we develop simplified representations o f the estuary physics that reproduce the tidally-averaged circulation, SSC distribution, and oxygen depletion. These models show that SSC and oxygen concentrations are ...


The Effect Of Tidal Asymmetry And Temporal Settling Lag On Sediment Trapping In Tidal Estuaries, Alexander S. Chernetsky, Henk M. Schuttelaars, Stefan A. Talke Sep 2010

The Effect Of Tidal Asymmetry And Temporal Settling Lag On Sediment Trapping In Tidal Estuaries, Alexander S. Chernetsky, Henk M. Schuttelaars, Stefan A. Talke

Civil and Environmental Engineering Faculty Publications and Presentations

Over decades and centuries, the mean depth of estuaries changes due to sea-level rise, land subsidence, infilling, and dredging projects. These processes produce changes in relative roughness (friction) and mixing, resulting in fundamental changes in the characteristics of the horizontal (velocity) and vertical tides (sea surface elevation) and the dynamics of sediment trapping. To investigate such changes, a 2DV model is developed. The model equations consist of the width-averaged shallow water equations and a sediment balance equation. Together with the condition of morphodynamic equilibrium, these equations are solved analytically by making a regular expansion of the various physical variables in ...


Suspended Sediment Fluxes At An Intertidal Flat: The Shifting Influence Of Wave, Wind, Tidal, And Freshwater Forcing, Stefan A. Talke, Mark T. Stacey Jan 2008

Suspended Sediment Fluxes At An Intertidal Flat: The Shifting Influence Of Wave, Wind, Tidal, And Freshwater Forcing, Stefan A. Talke, Mark T. Stacey

Civil and Environmental Engineering Faculty Publications and Presentations

Using in situ, continuous, high frequency (8–16 Hz) measurements of velocity, suspended sediment concentration (SSC), and salinity, we investigate the factors affecting near-bed sediment flux during and after a meteorological event (cold front) on an intertidal flat in central San Francisco Bay. Hydrodynamic forcing occurs over many frequency bands including wind wave, ocean swell, seiching (500–1000 s), tidal, and infra-tidal frequencies, and varies greatly over the time scale of hours and days. Sediment fluxes occur primarily due to variations in flow and SSC at three different scales: residual (tidally averaged), tidal, and seiching. During the meteorological event, sediment ...


Hydrodynamics And Morphology In The Ems/Dollard Estuary: Review Of Models, Measurements, Scientific Literature, And The Effects Of Changing Conditions, Stefan A. Talke, Huib E. De Swart Jan 2006

Hydrodynamics And Morphology In The Ems/Dollard Estuary: Review Of Models, Measurements, Scientific Literature, And The Effects Of Changing Conditions, Stefan A. Talke, Huib E. De Swart

Civil and Environmental Engineering Faculty Publications and Presentations

The Ems estuary has constantly changed over the past centuries both from man-made and natural influences. On the time scale of thousands of years, sea level rise has created the estuary and dynamically changed its boundaries. More recently, storm surges created the Dollard sub-basin in the 14th -15th centuries. Beginning in the 16th century, diking and reclamation of land has greatly altered the surface area of the Ems estuary, particularly in the Dollard. These natural and anthropogenic changes to the surface area of the Ems altered the flow patterns of water, the tidal characteristics, and the patterns of sediment deposition ...