Grain‐Size, Sediment‐Transport Regime, and Channel Slope in Alluvial Rivers

Dade, W. Brian; Friend, P. F.

doi:10.1086/516052

Cited by 256 publications

(189 citation statements)

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“…Theory and observation have confirmed that single-channel (nonbraided) rivers with gravel beds exhibit an equilibrium geometry, in which width, depth, and slope adjust such that fluid stress slightly exceeds the threshold of sediment motion in the channel center and is at threshold on the channel banks [19][20][21][22][23][24]. This idea has not been tested on the multiple dynamic channels within a braided stream.…”

Section: Introductionmentioning

confidence: 99%

Diffusive evolution of experimental braided rivers

et al. 2014

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Water flowing over a loose granular bed organizes into a braided river, a network of ephemeral and interacting channels. The temporal and spatial evolution of this network of braided channels is not yet quantitatively understood. In ∼1 m-scale experiments, we found that individual channels exhibit a self-similar geometry and near-threshold transport conditions. Measurements of the rate of growth of topographic correlation length scales, the time scale of system-slope establishment, and the random spatial decorrelation of channel locations indicate together that the evolution of the braided river system may be diffusive in nature. This diffusion is due to the separation of scales between channel formation and network evolution, and the random motion of interacting channels when viewed at a coarse-grained scale. Water flowing over a loose granular bed organizes into a braided river, a network of ephemeral and interacting channels. The temporal and spatial evolution of this network of braided channels is not yet quantitatively understood. In ∼ 1 m-scale experiments, we found that individual channels exhibit a self-similar geometry and near-threshold transport conditions. Measurements of the rate of growth of topographic correlation length scales, the time scale of system-slope establishment, and the random spatial decorrelation of channel locations indicate together that the evolution of the braided river system may be diffusive in nature. This diffusion is due to the separation of scales between channel formation and network evolution, and the random motion of interacting channels when viewed at a coarse-grained scale.

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Section: Introductionmentioning

confidence: 99%

Diffusive evolution of experimental braided rivers

et al. 2014

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“…Estos valores del d50 pertenecen al grupo textural de limos finos y muy finos, lo que indica la presencia de material en suspensión muy similar en las dos épocas climáticas, aun cuando la competencia del río es muy diferente. Dade & Friend (1998) realizaron una clasificación del tipo de transporte que predomina en un río a partir del cociente de la velocidad de caída del grano y la velocidad de corte ( * ). Cuando * < 0,3 predomina el transporte de sedimentos en suspensión; si 0,3 < * < 3, predomina un transporte mixto y si * ≥ 3 predomina el transporte de fondo.…”

Section: Fechaunclassified

“…Según esta clasificación, en esta zona del Río Magdalena existe un predominio significativo de transporte de sedimentos en suspensión, independientemente de la época climática. Además, al comparar estos resultados con el gráfico de la fracción total del transporte de sedimentos de fondo, en función del cociente * y profundidad relativa (cociente entre la profundidad del río y el espesor de la capa de carga del lecho) que en esta zona es del orden de 10 4 (Dade & Friend, 1998;Church, 2006), se observó que la fracción del transporte de sedimentos de fondo es <5% del transporte total de sedimentos. Este resultado es consistente con los valores de transporte de fondo estimados en las tres formulaciones analizadas.…”

Section: Fechaunclassified

“…Estos parámetros brindan información sobre los procesos de transporte de sedimentos y turbulencia; por consiguiente, son necesarios en la implementación de modelos numéricos que permitan una mejor comprensión de los procesos físicos en desembocaduras y deltas; tales como dispersión de sedimentos y contaminantes, evolución morfológica del fondo y transporte de sedimentos del fondo. Además, proporcionan información básica del sistema como por ejemplo el tipo de transporte de sedimentos predominante, definido a partir del cociente velocidad de corte y velocidad de caída del grano (Dade & Friend, 1998). Por su parte, el esfuerzo cortante sobre el lecho está relacionado con los procesos de transporte de fondo (Sumer et al, 1996), de acreción y erosión (Dyer, 1995) y la evolución de las geoformas del lecho (Van Rinj, 1993).…”

Section: Introductionunclassified

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Distribución vertical de sedimentos en suspension en la zona de desembocadura del Rio Magdalena, Colombia

Higgins¹,

Restrepo²,

Díaz³

et al. 2017

lajar

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), and high values in shear stress (1.1-5.8 Pa) were obtained. It can be said therefore that in the River Magdalena predominates sediment transport in suspension. The values of bottom sediment transport calculated with the three formulations represent lower rates to 5% of total sediment transport. The formulation of Meyer-Peter & Müller (1948) underestimate the transport of bottom sediment due to the conditions under which it was originally calibrated, while Nielsen (1992) and Ribberink (1998) formulations can generate better estimates, because they were originally calibrated with fine sediment, similar to the sediment type reported in the study area.

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“…Not only do modern long profiles not conform to a standard concave shape, it seems unlikely that any river long profile ever reaches 'equilibrium', since the controlling factors (discharge, sediment supply, base level, erodibility of the substrate) are likely always to change before the system has managed to adjust fully (Dade and Friend, 1998). Indeed 'the time required to produce a profile without significant convexities (>1.3 Ma) is long compared to the typical timescale of environmental change' (Phillips and Lutz, 2008, p. 565).…”

Section: Comparison Of Thementioning

confidence: 99%

Terrace reconstruction and long profile projection: a case study from the Solent river system near Southampton, England

Briant

Bates

Marshall

et al. 2012

Proceedings of the Geologists' Association

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(up to 200 words)River terrace sequences are important frameworks for archaeological evidence and as such it is important to produce robust correlations between what are often fragmentary remnants of ancient terraces. This paper examines both conceptual and practical issues related to such correlations, using a case study from the eastern part of the former Solent River system near Southampton, England. In this region two recent terrace schemes have been constructed using different data to describe the terrace deposits: one based mainly on terrace surfaces; the other on gravel thicknesses, often not recording the terrace surface itself. The utility of each of these types of data in terrace correlation is discussed in relation to the complexity of the record, the probability of post-depositional alteration of surface sediments and comparison of straight-line projections with modern river long profiles. Correlation using age estimates is also discussed, in relation to optically-stimulated luminescence dating of sand lenses within terrace gravels in this region during the PASHCC project. It is concluded that the need for replication at single sites means that this approach has limited use for correlative purposes, although dating of sediments is important for understanding wider landscape evolution and patterns of human occupation.2

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Grain‐Size, Sediment‐Transport Regime, and Channel Slope in Alluvial Rivers

Cited by 256 publications

References 1 publication

Diffusive evolution of experimental braided rivers

Diffusive evolution of experimental braided rivers

Distribución vertical de sedimentos en suspension en la zona de desembocadura del Rio Magdalena, Colombia

Terrace reconstruction and long profile projection: a case study from the Solent river system near Southampton, England

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