Physical Sciences and Mathematics Commons^™

Erosion In Extruder Flows: Analytical And Numerical Study, Miron Kaufman, Petru S. Fodor

Physics Faculty Publications

© 2017 Author(s). We consider the erosion of particles (e.g. carbonblack agglomerates) advected by the polymeric flow in a single screw extruder. We assume a particle to be made of primary fragments bound together. In the erosion process a primary fragment breaks out of a given particle. Particles disperse because of the shear stresses imparted by the fluid. The time evolution of the numbers of particles of different sizes is described by the Bateman coupled differential equations developed a century ago to model radioactivity. Using the particle size distribution we compute an entropic fragmentation index which varies from 0 for …

Tracing Sediment Erosion In The Yangtze River Subaqueous Delta Using Magnetic Methods, Can Ge, Weiguo Zhang, Chenyin Dong, Feng Wang, Huan Feng, Jianguo Qu, Lizhong Yu

Department of Earth and Environmental Studies Faculty Scholarship and Creative Works

We assessed the usefulness of magnetic properties for tracing sediment erosion in a deltaic environment. Surface and core sediments from the Yangtze River subaqueous delta were subjected to magnetic, granulometric, geochemical, and radionuclide analyses. Based on magnetic properties and particle size, the surface sediments can be divided into three groups. Groups I and II have a similar particle size distribution and geochemical composition, but the former has higher values of magnetic susceptibility (χ) and saturation isothermal remanent magnetization (SIRM). We interpret Group I as consisting of modern sediments, while Group II represents previously buried sediments that have undergone significant reductive …

East African Weathering Dynamics Controlled By Vegetation-Climate Feedbacks, Sarah J. Ivory, Michael M. Mcglue, Geoffrey S. Ellis, Adam Boehlke, Anne-Marie Lézine, Annie Vincens, Andrew S. Cohen

Earth and Environmental Sciences Faculty Publications

Tropical weathering has important linkages to global biogeochemistry and landscape evolution in the East African rift. We disentangle the influences of climate and terrestrial vegetation on chemical weathering intensity and erosion at Lake Malawi using a long sediment record. Fossil pollen, microcharcoal, particle size, and mineralogy data affirm that the detrital clays accumulating in deep water within the lake are controlled by feedbacks between climate and hinterland forest composition. Particle-size patterns are also best explained by vegetation, through feedbacks with lake levels, wildfires, and erosion. We develop a new source-to-sink framework that links lacustrine sedimentation to hinterland vegetation in tropical …

Geophysical Investigations Of Pyroclastic Density Current Processes And Deposit Properties At Mount St. Helens, Washington (Usa), Andrew Cleveland Gase

Boise State University Theses and Dissertations

Geophysical imaging has the potential to significantly improve investigations in pyroclastic deposits, either as a means of in situ property estimation or to provide geologic context where exposures do not exist. I perform two geophysical studies set in the deposits of the 1980 eruption at Mount St. Helens, Washington (USA); the aim is to investigate the physical properties and geology of pyroclastic deposits.

Joint petrophysical modeling reveals the dependence of seismic and electromagnetic velocities in pyroclastic deposits on two-phase porosity (vesicularity and inter- granular porosity) and water-saturation. Seismic first arrival travel-time tomography, multi-channel analysis of surface waves, and multi-offset GPR …

1999 - Salinas River Watershed Management Action Plan, Central Coast Regional Water Quality Control Board

Miscellaneous Monterey and San Luis Obispo County Documents and Reports

To more effectively protect and improve water resources, the Action Plan attempts to develop local solutions to local problems. Many significant identified water quality impacts in the Salinas River Watershed, such as erosion and sedimentation, nitrates in the groundwater and surface water, and older, discontinued pesticides in sediments and animal tissues, are primarily associated with nonpoint pollution sources. Also, widespread groundwater pumping contributes significantly to seawater intrusion into the coastal aquifers. The Action Plan approach includes: 1. devoting additional Regional Board resources to watershed activities, 2. increasing the Regional Board presence by developing partnerships with landowners, local governments, resource agencies …

Using Survey Data And Hec-Ras Modeling To Assess A Riffle-Remediation Structure On The Big River, Bonne Terre, Missouri, Nichole Renee Weedman

MSU Graduate Theses

Sediment transport and deposition in river channels can vary for many reasons including flooding, dredging, channel velocity, and grain size. On the Big River, the Army Corps of Engineers constructed a riffle ramp structure to trap and remediate lead-contaminated sediments. The performance of the structure is unknown. The goal of this study is to evaluate the storage capabilities of the riffle structure. To do this, survey data was collected to analyze sediment storage and entered into the HEC-RAS 5.0 to model the hydraulics of the channel before and after the riffle installation. Samples were collected to assess the level of …

Characterizing Landscape-Scale Erosion Using 10be In Detrital Fluvial Sediment: Slope-Based Sampling Strategy Detects The Effect Of Widespread Dams, Lucas J. Reusser, Paul R. Bierman, Donna M. Rizzo, Eric W. Portenga, Dylan H. Rood

College of Engineering and Mathematical Sciences Faculty Publications

Concentrations of in situ 10Be measured in detrital fluvial sediment are frequently used to estimate long-term erosion rates of drainage basins. In many regions, basin-averaged erosion rates are positively correlated with basin average slope. The slope dependence of erosion allows model-based erosion rate estimation for unsampled basins and basins where human disturbance may have biased cosmogenic nuclide concentrations in sediment. Using samples collected from southeastern North America, we demonstrate an approach that explicitly considers the relationship between average basin slope and erosion rate. Because dams and reservoirs are ubiquitous on larger channels in the field area, we selected 36 undammed …

Evidence Of Erosional Self-Channelization Of Pyroclastic Density Currents Revealed By Ground-Penetrating Radar Imaging At Mount St. Helens, Washington (Usa), Andrew C. Gase, Brittany D. Brand, John H. Bradford

Geosciences Faculty Publications and Presentations

The causes and effects of erosion are among the least understood aspects of pyroclastic density current (PDC) dynamics. Evidence is especially limited for erosional self-channelization, a process whereby PDCs erode a channel that confines the body of the eroding flow or subsequent flows. We use ground-penetrating radar imaging to trace a large PDC scour and fill from outcrop to its point of inception and discover a second, larger PDC scour and fill. The scours are among the largest PDC erosional features on record, at >200 m wide and at least 500 m long; estimated eroded volumes are on the order …

Effects Of Habitat Restoration On Soil Retention On Santa Rosa Island, Michael Perez, Kathryn Mceachern, Ken Niessen

STAR Program Research Presentations

Ranching began on Santa Rosa Island in the 1840’s, consequently introducing nonnative megafauna that put novel selective grazing pressures on endemic plant species. Their movement patterns also altered substrate integrity as the land became denuded of any stabilizing vegetation. Dense groves of island oak (Q. tomentella) are known to aid in sediment deposition and retention. The groves also function to collect water during periods of intense fog common to the island. This experiment sought to determine whether sediment is being lost or deposited on a ridge in the middle of the island containing a grove of Q. tomentella …

Revisions To Rainfall Intensity Algorithms In Przm5.0 To Improve Estimates Of Off-Field Runoff, Eroded Sediment And Pesticide Mass, Tammara Levey Estes

LSU Doctoral Dissertations

The Environmental Protection Agency (EPA) model Pesticide Root Zone Model, version 5.0 (PRZM5.0) is used to estimate off-field loadings of pesticide concentrations in runoff and eroded sediment. Climate change has resulted in an increase in rainfall intensity patterns for much of the United States. This change impacts off-field runoff and eroded sediment as well as off-field pesticide loads from agricultural fields. Thus, the PRZM5.0 EPA “lookup” table for runoff curve numbers and the internal algorithm for eroded sediment estimation have become outdated since both temporal and geographical conditions have changed. This research presents (1) a revised method for estimating runoff …

Weathering And Erosion Of Fractured Bedrock Systems, Marina I. Lebedeva, Susan L. Brantley

United States Geological Survey: Staff Publications

We explore the contribution of fractures (joints) in controlling the rate of weathering advance for a low-porosity rock by using methods of homogenization to create averaged weathering equations. The rate of advance of the weathering front can be expressed as the same rate observed in non-fractured media (or in an individual block) divided by the volume fraction of nonfractured blocks in the fractured parent material. In the model, the parent has fractures that are filled with a more porous material that contains only inert or completely weathered material. The low-porosity rock weathers by reaction-transport processes. As observed in field systems, …

Sedimentation And Erosion Patterns Within Anabranching Channels In A Lowland River Restoration Project, Ivan Medel

Cal Poly Humboldt theses and projects

Phase 2A of the Salt River Ecosystem Restoration Project (SRERP) was implemented to increase transport efficiency of water and sediment through a low gradient river reach to alleviate flooding on adjacent properties. The SRERP utilizes a unique anabranching channel design that concentrates base flows within a single deep, narrow channel overflowing onto an alternating series of higher elevation active benches at flood stages. This paper investigated the performance of the project’s hydraulic conveyance and general utility of anabranching channels as a restoration alternative by assessing the distribution and magnitude of deposition and erosion response patterns.

Aggradation was not observed within …

Towards A Prediction Of Landscape Evolution From Chemical Weathering And Soil Production, Eric Alan Jackson

Browse all Theses and Dissertations

The time evolution of a periodic landscape under the influence of chemical weathering and physical erosion is computed. The model used incorporates weathering and soil production as a flux limited reaction controlled by groundwater flow. Scaling of the flow rate is obtained from a percolation theoretic treatment. The erosion of the soil material produced by this process is modeled by the diffusion of elevation, as consistent with downslope soil transport proportional to the tangent of the angle of the topography, and application of the equation of continuity to surface soil transport. Three initial topographies are examined over a periods of …

Quaternary River Erosion, Provenance, And Climate Variability In The Nw Himalaya And Vietnam, Tara Nicole Jonell

LSU Doctoral Dissertations

The influence of Quaternary climate variation on sediment generation, storage, and transport in two mountainous Asian river basin was examined in the largest tributary to the upper Indus River in the Himalayan rain shadow, the Zanskar River basin (~15,000 km²), and the smaller, subtropical Song Gianh basin (<3,500 km²) of central Vietnam. Spatial patterns of erosion in the Zanskar River Basin were established to quantify the dominant controls on Quaternary sedimentation in the Himalayan rain shadow on the edge of the Tibetan Plateau. Glacial erosion and precipitation along the High Himalaya together dominate sediment production and transport …