نتایج جستجو برای: and gravel r2085
تعداد نتایج: 16827935 فیلتر نتایج به سال:
A 0.9 km-reach of Uvas Creek, California, was reconstructed as a sinuous, meandering channel in November 1995. In February 1996, this new channel washed out. We reviewed project documents to determine the basis for the project design and conducted our own historical geomorphological study to understand the processes operating in the catchment and project reach. The project was designed using a ...
Nonglacial deposits Artificial fill (Holocene)—Mud, sand, and gravel of varying proportions, possibly including foreign debris such as concrete, logs, timbers, or brick. Used for highway roadbeds and other construction. Thickness generally greater than 2 m. Mapped where fill substantially obscures or has altered original geologic deposit. Beach deposits (Holocene)—Soft sand, silt, and mud depos...
Two controlled flow events were generated by releasing water from a reservoir into the Olewiger Bach, located near Trier, Germany. This controlled release of near bank-full flows allowed an investigation of the fine sediment (<63 μm) mobilized from channel storage. Both a winter (November) and a summer (June) release event were generated, each having very different antecedent flow conditions. T...
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...
The use of gravels as syntectonic indicators of thrusting has recently been questioned by foreland-basin models that assign gravels to a post-thrusting interval of progradation, except in very proximal areas. On the basis of precise temporal control provided by magnetostratigraphically dated sections, the history of gravel progradation after a major thrusting and uplift event in the northwester...
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...
Bedload sheets are low-amplitude bedforms the are formed by sorting patterns in mixed-size sediment (gravel or gravel-sand mixtures). The features have been functionally linked to dune forms developed in sandy sediments and gravel dunes formed in river channels. There have been a number of attempts to place bedload sheets on extended versions of the bedform phase diagrams used to predict sand b...
Abstract: In recent years deadly earthquakes in seismic areas have caused special concerns regarding liquefaction phenomenon by researchers and specialists. Excess pore water pressure in loose sediments may cause phenomena such as boiling, shearing strength and dynamic stiffness reduction and lateral movements cause difficulties. Many remedial methods such as soil replacement with proper materi...
In this research, fractal relationships were used to evaluate the particle size distribution of the check dam. Three check dams with height of 2, 2 and 2.6 meters were selected and the hole was drilled same the height of the check dam at the sediment deposits. Then, depending on the color of the deposited layers, the thickness of the layers was determined and sampling was down from each layer t...
Large deposits of coal over vast expanse of lands attract mining companies, power stations and petrochemical companies and thus the development of coal towns with rail and road networks. High traffic volume of large quantities of coal across coal cities often result in the gradual accumulation of fine coal dust particles on road pavements, rail ballast and sleepers. The effect of coal dust on t...
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