Engineering Commons^™

Lagrangian Bedload Movement Prediction Using The Virtual Velocity Approach, Theodoros Kyriakopoulos

Masters Theses

The advances in particle tracking codes in the recent years has made possible to track the intermittent movement of a large number of sediment particles with precision and in an automated way. The present study used this technique to study the velocity of the particle while it is in motion, the length it travels once it gets mobilized until it deposits, and the time it rests once deposited until it gets mobilized again. New modeling equations were developed to predict these quantities for a wide range of flow conditions and sediment sizes. These equations were combined to predict the virtual …

Development Of An Rfid Tracking System For Coarse Sediment Transport In A Flume Setting, Peter Mahoney Jr.

ENGS 88 Honors Thesis (AB Students)

Development of an RFID Tracking System for Coarse Sediment Transport in a Flume Setting

Peter E. Mahoney

Professor Carl Renshaw

Understanding how sediment moves through a fluvial system has important implications for the study of river systems, sediment flux, and flood events. Over the past decade, RFID (radio frequency identification) technology has emerged as a useful method for tracking the movement and transport of coarse sediment clasts. This approach has been used to measure the transport of large clasts in mid-sized streams, ephemeral channels, and laboratory flume settings. However, this research utilized finite transport of sediment and focused on accurately …

Theoretical Model For Shields Diagram And Its Application, Jichao Jiang

Department of Environmental Engineering: Theses and Student Research

The transition from the condition of “no motion” to initial sediment moment, defined as sediment initiation, has been related to practical engineering (channel degradation, stable channel design), oceanographic (dredging, pipelines, cables), sedimentologic (sediment mobility, transport rates), geologic (the hydraulic interpretation of paleoenvironments), geochemical (pollutant transport), and gained considerable interest since nineteenth century.

Shields diagram for sediment initiation in terms of critical shear stress is a classic problem in sediment transport, but it is still an empirical law without a simple and practical theory despite extensive research since the 1930s. Hence, this research presents a simple theoretical model for critical shear …

Morphological Response Of Sand Bed Streams To Unsteady Flow Events: An Experimental Study, Etta Haley Gunsolus

Electronic Thesis and Dissertation Repository

Changes in riverine discharge, such as those due to reservoir flushing, seasonal variation or extreme precipitation events, can alter sediment transport rates and morphology of the stream bed. Experimental research investigated the effect of unsteady flow event hydrographs on stream bed morphological response. Laboratory experiments were conducted in a 5.0 m-long sediment transport flume with a bed comprised of a medium sand. Experimental hydrographs were composed of antecedent (base-flow), unsteady event (flood) and post- flood (return to base-flow) stages. Three distinct series of experimental laboratory runs were conducted to systematically investigate the effect of three characteristics of unsteady flow event …

Numerical Modeling Of The Effects Of Hydrologic Conditions And Sediment Transport On Geomorphic Patterns In Wetlands, Mehrnoosh Mahmoudi

FIU Electronic Theses and Dissertations

This dissertation focused on developing a numerical model of spatial and temporal changes in bed morphology of ridge and slough features in wetlands with respect to hydrology and sediment transport when a sudden change in hydrologic condition occurs. The specific objectives of this research were: (1) developing a two-dimensional hydrology model to simulate the spatial distribution of flow depth and velocity over time when a pulsed flow condition is applied, (2) developing a process-based numerical model of sediment transport coupled with flow depth and velocity in wetland ecosystems, and (3) use the developed model to explore how sediment transport may …

Best Management Practices Effectiveness To Reduce Sediment Transport To Morro Bay, Michael J. Randall

Master's Theses

The Morro Bay Watershed, which is located inSan Luis Obispo County,California, covers more than 48,000 acres of land and discharges intoMorroBaythrough the Morro Bay National Estuary (MBNE). The Chorro Creek Subwatershed consists of approximately 30,000 acres of the overall watershed. The MBNE provides an ecosystem that supports a variety of wildlife from the common sea gull to the endangered sea otter. The estuary is also home to over 200 species of birds. The operational waterfront of theMorroBayHarborwas and continues to be a strong supporter to the local economy of the City of Morro Bay. Numerous studies were conducted since the …

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 …

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 …

3d Numerical Modeling Of Hydrodynamic Flow, Sediment Deposition And Transport In Stormwater Ponds And Alluvial Channels, Leying Zhang

Civil & Environmental Engineering Theses & Dissertations

Prediction of flow and sediment transport is an important and challenging problem for stormwater management and river engineering applications. This thesis concerns primarily the computation of flow, sediment deposition and transport processes in stormwater ponds and alluvial channels based on a multiphase flow approach in modeling sediment transport. Starting from an existing hydrodynamic Reynolds Averaged Navier-Stokes flow solver, numerical models are developed to predict flow, sediment deposition and transport under the FLUENT software package. Two types of sediment transport models are formulated to consider quantities of present sediment phase volume fractions: a Discrete Phase Model in a Lagrangian frame where …

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 fluxes are …

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 …

Modeling Groundwater Flow And Contaminant Transporting Fractured Aquifers, Jason M. Bordas

Theses and Dissertations

The hybrid discrete fracture network/equivalent porous medium (DFN/EPM) model was selected for analysis and application to simulate a contaminated site in this study. The DFN/EPM was selected because it appeared to have the potential to aid decision making by remedial project managers at contaminated DoD fractured aquifer sites. This model can use data that are typically available at a site while incorporating the important processes relevant to describing contaminant transport in a fractured medium. The model was applied to simulate the operation of a pump-and-treat remedial action at a trichloroethene-contaminated fractured aquifer at Pease AFB. The model was able to …