Laboratory Investigation of Rill Erosion on Compost Blankets under Concentrated Flow Conditions

2010 ◽  
Vol 53 (4) ◽  
pp. 1077-1086
Author(s):  
X. Zhu ◽  
L. M. Risse ◽  
S. C. McCutcheon ◽  
E. W. Tollner ◽  
T. C. Rasmussen ◽  
...  
Keyword(s):  
Laboratory Investigation ◽  
Rill Erosion ◽  
Flow Conditions ◽  
Concentrated Flow

Field evaluation of sediment retention devices under concentrated flow conditions

2015 ◽  
Vol 15 (9) ◽  
pp. 2022-2031 ◽  
Author(s):  
Carlos Bulnes García ◽  
Joseph Monical ◽  
Rabin Bhattarai ◽  
Prasanta K. Kalita
Keyword(s):  
Field Evaluation ◽  
Flow Conditions ◽  
Sediment Retention ◽  
Concentrated Flow

Investagation of the sediment connectivity under freeze-thaw meltwater compound erosion condition on loessal slope

2021 ◽  
Author(s):  
Tian Wang ◽  
Peng Li ◽  
Jingming Hou ◽  
Zhanbin Li ◽  
Shengdong Cheng ◽  
...  
Keyword(s):  
Flow Rate ◽  
Laboratory Experiments ◽  
Overland Flow ◽  
Structural Connectivity ◽  
Surface Erosion ◽  
Rill Erosion ◽  
Erosion Process ◽  
Freeze Thaw ◽  
Concentrated Flow ◽  
Sediment Connectivity

<p>The connectivity of rill erosion and overland flow are significantly affected by freeze-thaw cycles. Meltwater concentrated flow laboratory experiments were carried out to assess the soil erosion connectivity of different frozen conditions based on simplified hydrological curve and relative surface connection function. The experiments were performed over frozen, shallow-thawed, and unfrozen soil-filled flumes under 1, 2, and 4 L/min flow rates with the temperature around 5 °C. The results imply that according to the spatial distribution of the high connected areas on the slope, the connectivity of the sediment structure on the slope is obviously enhanced with the increase of the flow rate. The order of the structural connectivity of the sediment on the slope with different freeze-thaw states under the same flow rate is: frozen slope > shallow-thawed slope > unfrozen slope. Under different flows and soil frozen conditions, the laws of the vertical and horizontal connectivity rates of the slope are relatively similar which increase first and then stabilize, while the horizontal connectivity rate first decreases and then stabilizes. From the perspective of horizontal connectivity, the erosion form at the beginning of the experiment was mainly surface erosion; as the experiment progressed, the erosion form gradually changed from surface erosion to rill erosion. The results of this research would provide specific implications about meltwater erosion connectivity for improving the erosion process understand.</p>

Effect of Soil Properties and Water Quality on Concentrated Flow Erosion (Rills, Ephermal Gullies and Pipes)

1996 ◽  
Author(s):  
Joe Bradford ◽  
Itzhak Shainberg ◽  
Lloyd Norton
Keyword(s):  
Soil Properties ◽  
Clay Mineralogy ◽  
Soil Surface ◽  
Fold Increase ◽  
Field Conditions ◽  
Rill Erosion ◽  
Concentrated Flow ◽  
Cohesive Forces ◽  
Hydraulic Shear ◽  
Bed Material

Concentrated flow erosion in rills, pipes, ephermal gullies, and gullies is a major contributor of downstream sedimentation. When rill or gullies form in a landscape, a 3- to 5-fold increase in soil loss commonly occurs. The balance between the erosive power of the flow and the erosion resistance of the bed material determines the rate of concentrated flow erosion. The resistance of the bed material to detachment depends primarily on the magnitude of the interparticle forces or cohesion holding the particles and aggregates together. The effect of soil properties on bed material resistance and concentrated flow erosion was evaluated both in the laboratory and field. Both rill erodibility and critical hydraulic shear were greater when measured in 9.0 m long rills under field conditions compared with laboratory mini-flumes. A greater hydraulic shear was required to initiate erosion in the field compared to the mini-flume because of the greater aggregate and clod size and stability. Once erosion was initiated, however, the rate of erosion as a function of hydraulic shear was greater under field conditions because of the greater potential for slaking upon wetting and the greater soil surface area exposed to hydraulic shear. Erosion tests under controlled laboratory conditions with the mini-flume allowed individual soil variables to be studied. Attempts to relate rill erosion to a group soil properties had limited success. When individual soil properties were isolated and studied separately or grouped separately, some trends were identified. For example, the effect of organic carbon on rill erodibility was high in kaolinitic soils, low in smectitic soils, and intermediate in the soils dominated by illite. Slow prewetting and aging increased the cohesion forces between soil particles and decreased rill erodibility. Quick prewetting increased aggregate slaking and increased erodibility. The magnitude of the effect of aging depended upon soil type. The effect of clay mineralogy was evaluated on sand/clay mixtures with montmorillonite (M), Illite (I), and kaolinite (K) clays. Montmorillonite/sand mixtures were much less erodible than either illite or kaolonite sand mixtures. Na-I and Na-K sand mixtures were more erodible than Ca-I and Ca-K due to increased strength from ionic bonding and suppression of repulsive charges by Ca. Na-M was less erodiblethan Ca-M due to increased surface resulting from the accessibility of internal surfaces due to Na saturation. Erodibility decreased when salt concentration was high enough to cause flocculation. This occurred between 0.001 mole L-1 and 0.01 mole L-1. Measuring rill erodibility in mini-flumes enables the measurement of cohesive forces between particles and enhances our ability to learn more about cohesive forces resisting soil detachment under concentrated water flow.

Thrombus formation on artificial surfaces: Correlative microscopy

1990 ◽  
Vol 48 (3) ◽  
pp. 840-841
Author(s):  
Quintin J. Lai ◽  
Stuart L. Cooper ◽  
Ralph M. Albrecht
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Low Voltage ◽  
Thrombus Formation ◽  
Blood Platelets ◽  
Polymer Surfaces ◽  
Flow Conditions ◽  
Transmission Electron ◽  
Adhesion Of Platelets ◽  
Microscopic Techniques

Thrombus formation and embolization are significant problems for blood-contacting biomedical devices. Two major components of thrombi are blood platelets and the plasma protein, fibrinogen. Previous studies have examined interactions of platelets with polymer surfaces, fibrinogen with platelets, and platelets in suspension with spreading platelets attached to surfaces. Correlative microscopic techniques permit light microscopic observations of labeled living platelets, under static or flow conditions, followed by the observation of identical platelets by electron microscopy. Videoenhanced, differential interference contrast (DIC) light microscopy permits high-resolution, real-time imaging of live platelets and their interactions with surfaces. Interference reflection microscopy (IRM) provides information on the focal adhesion of platelets on surfaces. High voltage, transmission electron microscopy (HVEM) allows observation of platelet cytoskeletal structure of whole mount preparations. Low-voltage, high resolution, scanning electron microscopy allows observation of fine surface detail of platelets. Colloidal gold-labeled fibrinogen, used to identify the Gp Ilb/IIIa membrane receptor for fibrinogen, can be detected in all the above microscopies.

Hydrodynamic flow conditions through permeable walls

1992 ◽  
Vol 2 (8) ◽  
pp. 1565-1569
Author(s):  
S. Vollmar ◽  
J. A. M. S. Duarte
Keyword(s):  
Hydrodynamic Flow ◽  
Flow Conditions ◽  
Permeable Walls
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