نتایج جستجو برای: gravel bed
تعداد نتایج: 52222 فیلتر نتایج به سال:
[1] Steep, rough channels occupy a large fraction of the total channel length in mountainous regions. Most sediment mobilized on hillslopes must pass through these streams before reaching lower-gradient channels. Steep channels have wide grain size distributions that are composed of finer, more mobile sediment and large, rarely mobile grains. The large grains can bear a significant portion of t...
Sediment-maintenance flushing flows designed to mimic the action of natural floods in removing the accumulated fine sediments from the channel and loosening the gravel bed have been increasingly proposed as an effective alternative in dam management and a required component of riverine restoration programmes. However, reservoir releases are generally associated with financial and environmental ...
Laboratory studies were conducted to investigate scrap-tire-shreds as a potential alternative to conventional gravel in the drainage layer of leachate collection system at the base of landfill. Performance of various physico-chemical characteristics of leachate after passing it through combined bed of scrap-tire-shreds and gravel for different combinations of thickness of scrap-tireshreds and g...
Median grain sizes on riverbeds range from boulders in uplands to silt in lowlands; however, rivers with ~1–5mm diameter bed sediment are rare. This grain size gap also marks an abrupt transition between graveland sand-bedded reaches that is unlike any other part of the fluvial network. Abrupt gravel-sand transitions have been attributed to rapid breakdown or rapid transport of fine gravel, or ...
Decisions about flood protection and river rehabilitation require prediction of the consequences of each possible management alternative. To provide such predictions, an integrative model is required that represents the cause-effect relations between revitalisation measures and morphologic, hydraulic and ecological consequences. This paper describes the hydraulics submodel of such an integrativ...
The relation between the equivalent roughness and different grain size percentiles of the sediment in gravel-bed rivers was determined under the hypothesis that the vertical distribution of the flow velocity follows a logarithmic law. A set of 954 data points was selected from rivers with gravel size sediment or larger, with a non-sinuous alignment and free of vegetation or obstacles. According...
The dynamics of river bed evolution are known to be notoriously complex affected by near-bed turbulence, the collective motion of clusters of particles of different sizes, and the formation of bedforms and other large-scale features. In this paper, we present the results of a study aiming to quantify the inherent nonlinearity and complexity in gravel bed dynamics. The data analyzed are bed elev...
This paper addresses the issue of polishing electroplating wastewater in subsurface vertical flow constructed wetland. Electroplating wastewater treatment or polishing in constructed wetlands (CWs) was studied to a very limited degree. Four types of microcosm upflow constructed wetlands were selected for the experiment based on type of bed media and the presence or absence of vegetation (Phragm...
[1] The first extensive dataset on subaqueous bed material grain size in a large river subject to reduced sediment supply is investigated alongside bathymetry, modeled flow, and sediment flux. Results suggest that following sediment supply decline and a shift to a finer sediment supply, the gravel‐sand transition (GST) in fluvial systems extends and subsequently migrates upstream. The non‐abrup...
This studyis part of a collaborativeeffortbetweenMontanaTechand AtlanticRichfield Companyto find solutions for treating metal-contaminated surface runoff from the surrounding city of Butte, Montana. The runoff flows into a storm drai% which transports the suspended and dissolved metals into nearby Silver Bow Creek, a tributary of the Clark Fork River. The study compared percent removal of metrd...
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