نتایج جستجو برای: sediment threshold
تعداد نتایج: 158501 فیلتر نتایج به سال:
Spatial variations in composition of marine microbial communities and its causes have largely been disclosed in studies comprising rather large environmental and spatial differences. In the present study, we explored if a moderate but temporally permanent climatic division within a contiguous arctic shelf seafloor was traceable in the diversity patterns of its bacterial and archaeal communities...
Prediction of sediment load transported by rivers is a crucial step in the management of rivers, reservoirs and hydraulic projects. In the present study, in order to predict the suspended sediment of Taleghan river by using artificial neural network, and recognize the best ANN with the highest accuracy, 500 daily data series of flow discharge on the present day, flow discharge on the past day...
The movement of fluvial sediment shapes our rivers. Understanding sediment entrainment has been a goal of hydraulic engineers for almost a century1,2. Previous sediment entrainment models have been informed by laboratory experiments using grains that were free from biological material3. In natural river settings, however, sediments are invariably covered by bacteria, often forming visible biofi...
Adsorption is a key water pollution remediation measure used to achieve stormwater quality improvement in Sustainable urban Drainage Systems (SuDS). The level of contamination of detained sediment within SuDS assets is not well documented, with published investigations limited to specific contaminant occurrence in ponds, wetlands or infiltration devices (bioretention cells) and generally focuse...
Wind erosion of soil is an appreciable but unstudied event following fires in cold desert. We examined aeolian transport of sediment for one year following fire in semiarid shrub steppe of southern Idaho. Sediment collectors were used to determine horizontal mass transport of soil ( ) and saltation sensors and anemometers were used to determine saltation activity (# seconds saltation is detecte...
Wind erosion of soil is an appreciable but unstudied event following fires in cold desert. We examined aeolian transport of sediment for 1 year following fire in semi-arid shrub steppe on loess soils in southern Idaho, USA. Sediment collectors were used to determine horizontal mass transport of soil and saltation sensors and anemometers were used to determine saltation activity (fraction of tim...
The historical and ongoing lead (Pb) contamination caused by the 20th-century use of leaded gasoline was investigated by an analysis of bottom sediment in eight small rural reservoirs in eastern Kansas, USA. For the reservoirs that were completed before or during the period of maximum Pb emissions from vehicles (i.e., the 1940s through the early 1980s) and that had a major highway in the basin,...
A substantial amount of laboratory and field research on selenium effects to biota has been accomplished since the national water quality criterion was published for selenium in 1987. Many articles have documented adverse effects on biota at concentrations below the current chronic criterion of 5 microg/L. This commentary will present information to support a national water quality criterion fo...
When they reach a flat plain, rivers often deposit their sediment load into a cone-shaped structure called alluvial fan. We present a simplified experimental setup that reproduces, in one dimension, basic features of alluvial fans. A mixture of water and glycerol transports and deposits glass beads between two transparent panels separated by a narrow gap. As the beads, which mimic natural sedim...
Experiments were conducted to evaluate the influence of sediment concentration, slope and discharge on sediment deposition rates and patterns associated with a reduction in bed slope. Analysis of the data shows that up to a certain unit discharge a simple settling equation without a transport term gives a good prediction of the sediment delivery ratio and the grain-size distribution of the depo...
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