The Curious Case of Mobility Reversal in Sediment Mixtures

Solari, Luca; Parker, Gary

doi:10.1061/(asce)0733-9429(2000)126:3(185)

Cited by 40 publications

(28 citation statements)

References 25 publications

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“…-The empirical equations and physical explanations seem to converge on the conditions for which the bankfull cross-section (geometry and width) attains to the formative discharge able to entrain the D 50 of the bed surface. -The measured phenomenon of coarsening reflects some similar aspects of the Brummer and Montgomery's (2003) findings for headwater streams, and to Solari and Parker's (2000) flume experiments. We suppose that such a phenomenon is evident for those headwater streams, such as the upper Cordevole river, where the sources of sediment are low, and where cobbles and boulders are available in the substratum when the channel begins to form.…”

Section: Discussionsupporting

confidence: 83%

Bankfull width and morphological units in an alpine stream of the dolomites (Northern Italy)

Vianello

D’Agostino

2007

Geomorphology

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Section: Discussionsupporting

confidence: 83%

Bankfull width and morphological units in an alpine stream of the dolomites (Northern Italy)

Vianello

D’Agostino

2007

Geomorphology

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“…In shallow experimental flows where D approaches h, coarser particles may be more prone to overpassing onto the bars than in nature because of limited water depth relative to particle size (Carling, 1990). Furthermore, in extreme cases of channel slopes of about 0.05, the relative mobility of finer and coarser sediment reverses because the bed tilt significantly changes the force balance on the large exposed particles (Solari and Parker, 2000).…”

Section: Sediment Transport Similaritymentioning

confidence: 99%

Quantifiable effectiveness of experimental scaling of river- and delta morphodynamics and stratigraphy

Kleinhans

Dijk

Lageweg

et al. 2014

Earth-Science Reviews

121

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N. (2014) 'Quantiable eectiveness of experimental scaling of river-and delta morphodynamics and stratigraphy.', Earth-science reviews., 133 . pp. 43-61. Further information on publisher's website:http://dx.doi.org/10.1016/j.earscirev.2014.03.001Publisher's copyright statement: NOTICE: this is the author's version of a work that was accepted for publication in Earth-Science Reviews. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reected in this document. Changes may have been made to this work since it was submitted for publication. A denitive version was subsequently published in Earth-Science Reviews, 133, June 2014, 10.1016/j.earscirev.2014.03.001. Additional information:Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. AbstractLaboratory experiments to simulate landscapes and stratigraphy often suffer from scale effects, because reducing lengthand time scales leads to different behaviour of water and sediment. Classically, scaling proceeded from dimensional analysis of the equations of motion and sediment transport, and minor concessions, such as vertical length scale distortion, led to acceptable results. In the past decade many experiments were done that seriously violated these scaling rules, but nevertheless produced significant and insightful results that resemble the real world in quantifiable ways.Here we focus on self-formed fluvial channels and channel patterns in experiments. The objectives of this paper are 1) to identify what aspects of scaling considerations are most important for experiments that simulate morphodynamics and stratigraphy of rivers and deltas, 2) to establish a design strategy for experiments based on a combination of relaxed classical scale rules, theory of bars and meanders, and small-scale experiments focussed at specific processes. We present a number of small laboratory setups and protocols that we use to rapidly quantify erosive and sedimentary types of forms and dynamics that develop in the landscape experiments as a function of detailed properties such as effective material strength and to assess potential scale effects. Most importantly, the width-to-depth ratio of channels determines the bar pattern and meandering tendency. The strength of floodplain material determines these channel dimensions, and theory predicts that laboratory rivers should have 1.5 times larger width-to-depth ratios for the same bar pattern. We show how floodplain formation can be controlled by a...

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“…Stepping back from the details of predicting downstream sorting in a specific modern stream, however, leads us to ask if the sorting problem might be amenable to simplification for stratigraphic time and space scales. The rate of downstream fining in a depositional fluvial system fundamentally depends on the following three things: (1) the range of sizes in the sediment supply (there can be no fining if the supply is too well sorted); (2) the extent and spatial distribution of deposition in the fluvial system (selective deposition cannot operate without deposition); and (3) hydraulic, topographic, and grain‐interaction effects that result in relatively greater mobility of finer grain sizes (see the work of Solari and Parker [2000] for an interesting exception). Although the first two effects are implicitly represented in typical sorting models, the main emphasis has been on factor 3.…”

Section: Downstream Sediment Fining and The Concept Of Similarity: Ovmentioning

confidence: 99%

Similarity solutions for fluvial sediment fining by selective deposition

Fedele¹,

Paola²

2007

J. Geophys. Res.

245

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[1] Current models for downstream sediment sorting by selective deposition generally perform well at describing observed sorting data. However, since most were developed initially for application to modern rivers, they are typically formulated in terms of hydraulic and bed-surface variables that are not readily measurable in the sedimentary record. Moreover, their algebraic complexity obscures some of the underlying simplicity of the segregation process. Here we show how a pair of hydraulically based sorting models developed by Parker et al. can be reformulated, with minimal loss of accuracy, in terms of the size distribution of the supplied sediment and the downstream depositional mass balance. By invoking constant dimensionless shear stress within either the gravel or sand regimes, reach-scale, short-term details of hydraulics and sediment transport are summarized via a pair of dimensionless relative mobility functions, one for gravel and one for sand. Our approach yields simplified similarity solutions in which the long-term longitudinal grain-size distribution of the substrate and the relative mobility functions can be collapsed into self-similar forms in which only local mean and standard deviation of sizes in transport are used as scaling parameters. The formulation we propose offers a simple means to explore the impact of controlling variables on fining profiles and can be easily incorporated in long-term, basin-scale numerical stratigraphic models, avoiding the necessity of modeling the details of hydraulics and sediment transport. The model involves a minimum number of physically based parameters, the numerical values of which can be determined from the spatial distribution of rate of deposition, dimensionless shear stress, and the coefficient of variation of the supply gravel or sand size distributions. Downstream Sediment Fining and the Concept of Similarity: Overview[2] A common geomorphic observation in fluvial systems is their ability to sort sediments via several physical mechanisms. In particular, the tendency of bed material to become finer downstream is a critical property of aggrading rivers that must be accounted for when modeling fluvial systems since it is a primary driver of downstream changes in river planform and depositional facies [Leopold and Wolman, 1957;Heller and Paola, 1992;Paola et al., 1992a;Paola, 2000]. The two most common explanations for fluvial downstream fining are (1) abrasion, a mechanism in which large particles break down into smaller sizes by fracturing and attrition; and (2) selective deposition, a process that can be viewed as a kind of hydraulically driven sediment fractionation [Paola, 1988;Parker, 1991;Paola et al., 1992a;Ferguson et al., 1996;Rice, 1999]. The observations that fining rates are strongly positively correlated with deposition lengths, and that observed fining rates in natural depositional streams are often orders of magnitude higher than those that appear possible by abrasion alone, indicate that selective deposition is the dominant factor that ca...

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The Curious Case of Mobility Reversal in Sediment Mixtures

Cited by 40 publications

References 25 publications

Bankfull width and morphological units in an alpine stream of the dolomites (Northern Italy)

Bankfull width and morphological units in an alpine stream of the dolomites (Northern Italy)

Quantifiable effectiveness of experimental scaling of river- and delta morphodynamics and stratigraphy

Similarity solutions for fluvial sediment fining by selective deposition

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