scholarly journals Assessing Controls on the Displacement of Tracers in Gravel-Bed Rivers

Water ◽  
2019 ◽  
Vol 11 (8) ◽  
pp. 1598 ◽  
Author(s):  
Daniel Vázquez-Tarrío ◽  
Ramon J. Batalla
Keyword(s):  
Channel Morphology ◽  
Flow Strength ◽  
Gravel Bed ◽  
Structure Flow ◽  
Gravel Bed Rivers ◽  
The One ◽  
Individual Grains ◽  
Event Based ◽  
The Relationship ◽  
Travel Length

Particle travel length is one of the main dimensions of bedload and strongly influences river morpho-dynamics, particularly when exploring the interactions between sediment transport and channel morphology. This process has been traditionally studied by using tagged stones that allow tracking the movement experienced by individual grains during transport episodes. In this paper, we relate measured particle travel lengths to flow metrics and river channel parameters. First, we link the event-based bedload volumes to the active-layer dimensions, and the product between the average bedload rates and the duration of competent flows. We then hypothesize that travel length depends on channel width, surface grain-size, particle size, bed structure, flow strength, and duration of competent flow. The results from this approach are, subsequently, tested with a set of tracer observations from eight rivers that were available in the literature. The relationship between travel length and flow metrics was found to be statistically strong and has the potential to allow us to quantitatively assess the one-day dynamics of particles moving along streambeds. We also analyzed the influence of channel morphology and bed structure and identified morphological signatures for particle transport in gravel-bed rivers.

scholarly journals The Prediction of Fine Sediment Distribution in Gravel-Bed Rivers Using a Combination of DEM and FNN

Water ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 1515
Author(s):  
Van Hieu Bui ◽  
Minh Duc Bui ◽  
Peter Rutschmann
Keyword(s):  
Feedforward Neural Networks ◽  
Fine Sediment ◽  
Sediment Distribution ◽  
Gravel Bed ◽  
Fine Sediments ◽  
Porosity Variation ◽  
Sediment Sorting ◽  
Gravel Bed Rivers ◽  
Bed Material ◽  
The Relationship

Large amounts of fine sediment infiltration into void spaces of coarse bed material have the ability to alter the morphodynamics of rivers and their aquatic ecosystems. Modelling the mechanisms of fine sediment infiltration in gravel-bed is therefore of high significance. We proposed a framework for calculating the sediment exchange in two layers. On the basis of the conventional approaches, we derived a two-layer fine sediment sorting, which considers the transportation of fine sediment in the form of infiltration into the void spaces of the gravel-bed. The relationship between the fine sediment exchange and the affected factors was obtained by using the discrete element method (DEM) in combination with feedforward neural networks (FNN). The DEM model was validated and applied for gravel-bed flumes with different sizes of fine sediments. Further, we developed algorithms for extracting information in terms of gravel-bed packing, grain size distribution, and porosity variation. On the basis of the DEM results with this extracted information, we developed an FNN model for fine sediment sorting. Analyzing the calculated results and comparing them with the available measurements showed that our framework can successfully simulate the exchange of fine sediment in gravel-bed rivers.

scholarly journals Infiltration Depth of Mineral Particles in Gravel-Bed Rivers

Minerals ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1285
Author(s):  
Natalia Bustamante-Penagos ◽  
Yarko Niño
Keyword(s):  
Relative Density ◽  
Fine Particles ◽  
Reynolds Numbers ◽  
Fine Sediment ◽  
Infiltration Depth ◽  
Gravel Bed ◽  
Mineral Particles ◽  
Gravel Bed Rivers ◽  
Relationship Of ◽  
The Relationship

This article discusses the results of an experimental study of a spill of mineral particles in gravel-bed rivers due to mining accidents. The purpose of this research is to characterize the dynamics of the fine mining particles spilled on a bed of immobilized gravel as a hyper-concentrated mixture and to experimentally characterize the infiltration phenomenon. We analyzed the type of infiltration considering the dimensionless coarse to fine particle size relationship, the dimensionless weight of the fine particles, the relative density of the particles, and the relationship between the subsurface and surface velocities, in addition to the densimetric Froude and Reynolds numbers of the fine particles. We found that the dimensionless infiltration depth is not associated with hydraulic parameters or the weight of the fine sediment spilled; however, fine sediment deposition decreases with depth, and infiltration depth may increase if subsurface flow decreases over time. Finally, a relationship of the dimensionless maximum infiltration depth with the relative density of the mining particles, the ratio of the bed sediment and the mining particles sizes, and the ratio between the subsurface and surface velocities is established.

Rhythmic roughness elements and channel morphology of gravel bed rivers

2014 ◽  
Vol 58 (3) ◽  
pp. 337-366 ◽  
Author(s):  
Paolo Billi ◽  
Emanuele Preciso ◽  
Enzo Salemi
Keyword(s):  
Channel Morphology ◽  
Gravel Bed ◽  
Roughness Elements ◽  
Gravel Bed Rivers

Misreading Egypt

2018 ◽  
Author(s):  
Jesse Schotter
Keyword(s):  
New Media ◽  
Narrative Form ◽  
Experimental Film ◽  
Tower Of Babel ◽  
Avant Garde ◽  
Sergei Eisenstein ◽  
History Of ◽  
The One ◽  
The Relationship ◽  
Modern Technologies

The first chapter of Hieroglyphic Modernisms exposes the complex history of Western misconceptions of Egyptian writing from antiquity to the present. Hieroglyphs bridge the gap between modern technologies and the ancient past, looking forward to the rise of new media and backward to the dispersal of languages in the mythical moment of the Tower of Babel. The contradictory ways in which hieroglyphs were interpreted in the West come to shape the differing ways that modernist writers and filmmakers understood the relationship between writing, film, and other new media. On the one hand, poets like Ezra Pound and film theorists like Vachel Lindsay and Sergei Eisenstein use the visual languages of China and of Egypt as a more primal or direct alternative to written words. But Freud, Proust, and the later Eisenstein conversely emphasize the phonetic qualities of Egyptian writing, its similarity to alphabetical scripts. The chapter concludes by arguing that even avant-garde invocations of hieroglyphics depend on narrative form through an examination of Hollis Frampton’s experimental film Zorns Lemma.

Researching (with) Major Food Retailers

2015 ◽  
Vol 15 (3) ◽  
pp. 33-39 ◽  
Author(s):  
David Evans
Keyword(s):  
Food Systems ◽  
Academic Research ◽  
Social Scientists ◽  
Major Food ◽  
Food Retailers ◽  
Food Retailer ◽  
The One ◽  
The Uk ◽  
The Relationship ◽  
Opening Up

This paper considers the relationship between social science and the food industry, and it suggests that collaboration can be intellectually productive and morally rewarding. It explores the middle ground that exists between paid consultancy models of collaboration on the one hand and a principled stance of nonengagement on the other. Drawing on recent experiences of researching with a major food retailer in the UK, I discuss the ways in which collaborating with retailers can open up opportunities for accessing data that might not otherwise be available to social scientists. Additionally, I put forward the argument that researchers with an interest in the sustainability—ecological or otherwise—of food systems, especially those of a critical persuasion, ought to be empirically engaging with food businesses. I suggest that this is important in terms of generating better understandings of the objectionable arrangements that they seek to critique, and in terms of opening up conduits through which to affect positive changes. Cutting across these points is the claim that while resistance to commercial engagement might be misguided, it is nevertheless important to acknowledge the power-geometries of collaboration and to find ways of leveling and/or leveraging them. To conclude, I suggest that universities have an important institutional role to play in defining the terms of engagement as well as maintaining the boundaries between scholarship and consultancy—a line that can otherwise become quite fuzzy when the worlds of commerce and academic research collide.

Choice Of Technique And The Volume Of Saving (A Re-Examination Of The Cobb-Douglas Model)

1968 ◽  
Vol 8 (4) ◽  
pp. 606-617
Author(s):  
Mohammad Anisur Rahman
Keyword(s):  
Economic Development ◽  
Production Function ◽  
Development Policy ◽  
Social Goals ◽  
The Other ◽  
Economic Development Policy ◽  
Labour Intensity ◽  
The One ◽  
Choice Of Technique ◽  
The Relationship

The purpose of this paper is to re-examine the relationship between the degree of aggregate labour-intensity and the aggregate volume of saving in an economy where a Cobb-6ouglas production function in its traditional form can be assumed to give a good approximation to reality. The relationship in ques¬tion has an obviously important bearing on economic development policy in the area of choice of labour intensity. To the extent that and in the range where an increase in labour intensity would adversely affect the volume of savings, a con¬flict arises between two important social objectives, i.e., higher rate of capital formation on the one hand and greater employment and distributive equity on the other. If relative resource endowments in the economy are such that such a "competitive" range of labour-intensity falls within the nation's attainable range of choice, development planners will have to arrive at a compromise between these two social goals.

Comparing gravel-bed rivers in paired urban and rural catchments of southeastern Pennsylvania

Geology ◽  
2000 ◽  
Vol 28 (1) ◽  
pp. 79-82 ◽  
Author(s):  
J. E. Pizzuto ◽  
W. C. Hession ◽  
M. McBride
Keyword(s):  
Gravel Bed ◽  
Gravel Bed Rivers

UNRAVELLING THE ROLE OF VEGETATION IN THE AVULSION HISTORY OF GRAVEL-BED RIVERS

2018 ◽  
Author(s):  
Daniel Donahue ◽  
◽  
José Antonio Constantine ◽  
Gregory B. Pasternack
Keyword(s):  
Gravel Bed ◽  
History Of ◽  
Gravel Bed Rivers

Bastard Feudalism and the Framing of Thirteenth-Century England

2018 ◽  
Author(s):  
Peter Coss
Keyword(s):  
Middle Ages ◽  
Thirteenth Century ◽  
Twelfth Century ◽  
The State ◽  
The Other ◽  
Great Work ◽  
Early Middle Ages ◽  
The One ◽  
The Relationship

In the introduction to his great work of 2005, Framing the Early Middle Ages, Chris Wickham urged not only the necessity of carefully framing our studies at the outset but also the importance of closely defining the words and concepts that we employ, the avoidance ‘cultural sollipsism’ wherever possible and the need to pay particular attention to continuities and discontinuities. Chris has, of course, followed these precepts on a vast scale. My aim in this chapter is a modest one. I aim to review the framing of thirteenth-century England in terms of two only of Chris’s themes: the aristocracy and the state—and even then primarily in terms of the relationship between the two. By the thirteenth century I mean a long thirteenth century stretching from the period of the Angevin reforms of the later twelfth century on the one hand to the early to mid-fourteenth on the other; the reasons for taking this span will, I hope, become clearer during the course of the chapter, but few would doubt that it has a validity.

Sign in / Sign up

Export Citation Format

Share Document