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Braid bar

About: Braid bar is a research topic. Over the lifetime, 44 publications have been published within this topic receiving 3964 citations.

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TL;DR: In this paper, it was shown that the braiding of marine waterways of the estuary zone occurs at an unknown time and place in the evolution of river morphological processes, which is among the most complex and least understood phenomenon in nature.
Abstract: River morphological processes are among the most complex and least understood phenomenon in nature. Recent research indicates that the braiding of marine waterways of the estuary zone occurs at an ...

6 citations

Journal ArticleDOI
TL;DR: In this article, the authors used the quadrant method for analyzing the turbulence characteristics of flow in the vicinity of a braid bar using 2-D bursting events technique, and the mean values contour of normalized ejection and sweep stress are plotted and their variation with the changing discharge is studied.
Abstract: Braided river is currently important topic of study; several scientists doing research on the complexity of braided river. However, the turbulent characteristics of flow around the braid bar is not thoroughly studied till now. In the current paper, the quadrant method is used for analyzing the turbulence characteristics of flow in the vicinity of bar using 2-D bursting events technique. Although many advances have been made within recent years in interpreting the mechanics of flow, transport of sediment and sedimentary architecture of braided rivers, many key issues remain to be addressed in particular the underlying processes of braid bar initiation. An attempt has been made herein to relate the depositional characteristics around the bar in the braided river model to the sweep and ejection bursting events. The concept of the hole is used in order to isolate the extreme events that contribute to the turbulent burst. The mean angle of sweep and ejection events possesses direct relationship with the scouring/ deposition characteristics in the vicinity of bar. The mean values contour of normalized ejection and sweep stress are plotted and their variation with the changing discharge is studied in this paper.

6 citations

Journal ArticleDOI
TL;DR: In this article, the authors examined the modern lower Ganges River by conducting a detailed process-oriented investigation of the main channel, channel margin and overbank deposits, supplemented by satellite image observation and comparison with other modern fluvial systems.
Abstract: The Ganges River, one of the largest rivers on Earth, is a typical monsoonal and flood-controlled system but has low inter-annual peak discharge variability. The seasonal discharge can reach 70 000 m3 s−1 during the wet season but maintains a low base flow of 500–3000 m3 s−1 during the dry season. However, the constancy in peak discharge every year categorizes the lower Ganges River as a river with low inter-annual peak discharge variability. This paper examines the modern lower Ganges River by conducting a detailed process-oriented investigation of the main channel, channel margin and overbank deposits, supplemented by satellite image observation and comparison with other modern fluvial systems. The channel and braid bar deposits show a dominance of small-scale to medium-scale cross-sets, with a variety of accretion processes constructing braid bars. The braid bar and channel deposits are typical of facies models of rivers with low inter-annual peak discharge variance. In contrast, the channel flank deposits are dominated by planar lamination, massive sand and mud couplets, and some ripple cross-lamination, with very little cross-bedding. Characteristic channel margin deposits represent sediments that accumulated by high-speed flows, multiple-surge and rapidly depositing flows, rapid or regular waning flows and hyperconcentrated flows. The overbank deposits predominantly comprise current ripples with long, thin bedforms and soft sediment deformation structures, which record flow transformation on the muddy flat topography and the processes of an unstable river bank. Our study shows that the channel margin and floodplain deposits are entirely different from those of the braid bar and channel. The bedform distribution of the fluvial deposits here (main channel, channel margin and overbank) may be an important tool in the identification of similar seasonal rivers with low inter-annual peak discharge variance and in the interpretation of fluvial processes. Supplementary material: The sediment texture and the depositional age is available at: https://doi.org/10.6084/m9.figshare.c.5144403

4 citations

01 Jan 1984
TL;DR: The Triassic Molteno Formation in the main Karoo Basin, South Africa, forms a northerly thinning intracratonic clastic wedge deposited by sandy braided rivers of South Saskatchewan type.
Abstract: The Triassic Molteno Formation in the main Karoo Basin, South Africa, forms a northerly thinning intracratonic clastic wedge deposited by sandy braided rivers of South Saskatchewan type. Deposition of the sandy facies was dominated by channel floor megaripples producing trough cross-bedded cosets; transverse bars, represented by solitary, large-scale planar sets are not significant. Departures from this regional pattern of sandstone deposition occur along the northern distal margin of the Molteno basin around Bethlehem in the Orange Free State. Here thickness trends and clast size delineate a deep channel system interpreted as the main braided exit channel from the basin. Because of its depth and constriction by local height differentials the competency and capacity of the flow were able to reproduce features more typical of proximal rather than distal depositional settings. The sandy facies is dominated by fine gravel with lesser amounts of coarse sand. Gravel occurs as longitudinal bars some of which contain low angle foreset stratification whose orientation is consistent with lateral growth and marginal riffle migration. The scale of the bars and simple depositional form imply that they may have been larger than modern equivalents and the flows deeper. The coarse sand occurs mainly as falling water stage features associated with the gravel bars. Shallow channel-fills, bar edge sand wedges, bar top sheet sands and thicker channel sands have been recognised and compared with similar features in modern and ancient braided stream sediments. When traced to the southeast the deep channel sediments contain few longitudinal gravel bars and more transverse bars; the vertical sequence from longitudinal to transverse bars at this locality points to the increasing distality of the depositional site through time.

3 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
20212
20202
20192
20184
20171
20151