Particle size of sediments collected from the bed of the Amazon River and its tributaries in June and July 1976

Nordin, Carl F.; Meade, Robert H.; Curtis, William F.; Bósio, Nivaldo J.; Delaney, B.M.

doi:10.3133/ofr77400

Cited by 8 publications

(3 citation statements)

References 1 publication

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“…Bed material samples generally have large mean diameters (a few 100 of µm) with a unique mode. Our data for bed material samples compare well with that of Nordin et al , 1977, 1979, 1980; and Mertes and Meade, 1985. Bed material samples from the Madeira River are slightly coarser than those from the Solimões River, as already reported by Mertes and Meade (1985).…”

Section: Resultssupporting

confidence: 91%

Prediction of depth‐integrated fluxes of suspended sediment in the Amazon River: particle aggregation as a complicating factor

Bouchez

Métivier

Lupker

et al. 2010

Hydrological Processes

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International audienceLarge rivers have been previously shown to be vertically heterogeneous in terms of suspended particulate matter (SPM) concentration, as a result of sorting of suspended solids. Therefore, the spatial distribution of suspended sediments within the river section has to be known to assess the riverine sedimentary flux. Numerous studies have focused on the vertical distribution of SPM in a river channel from a theoretical or experimental perspective, but only a few were conducted so far on very large rivers. Moreover, a technique for the prediction of depth-integrated suspended sediment fluxes in very large rivers based on sediment transport dynamics has not yet been proposed. We sampled river water along depth following several vertical profiles, at four locations on the Amazon River and its main tributaries and at two distinct water stages. Depending on the vertical profile, a one-to fivefold increase in SPM concentration is observed from river channel surface to bottom, which has a significant impact on the 'depth-averaged' SPM concentration. For each cross section, a so-called Rouse profile quantitatively accounts for the trend of SPM concentration increase with depth, and a representative Rouse number can be measured for each cross section. However, the prediction of this Rouse number would require the knowledge of the settling velocity of particles, which is dependent on the state of aggregation affecting particles within the river. We demonstrate that in the Amazon River, particle aggregation significantly influences the Rouse number and renders its determination impossible from grain-size distribution data obtained in the lab. However, in each cross section, the Rouse profile obtained from the fit of the data can serve as a basis to model, at first order, the SPM concentration at any position in the river cross section. This approach, combined with acoustic Doppler current profiler (ADCP) water velocity transects, allows us to accurately estimate the depth-integrated instantaneous sediment flux

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Section: Resultssupporting

confidence: 91%

Prediction of depth‐integrated fluxes of suspended sediment in the Amazon River: particle aggregation as a complicating factor

Bouchez

Métivier

Lupker

et al. 2010

Hydrological Processes

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“…where d 84 is bed grain diameter such that 84% of diameters are finer (Figure 7) [48]. The water density was calculated from the temperature T as:…”

Section: Transectmentioning

confidence: 99%

Bedform Morphology in the Area of the Confluence of the Negro and Solimões-Amazon Rivers, Brazil

Gualtieri

Martone

Filizola

et al. 2020

Water

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Confluences are common components of all riverine systems, characterized by converging flow streamlines and the mixing of separate flows. The fluid dynamics of confluences possesses a highly complex structure with several common types of flow features observed. A field study was recently conducted in the area of the confluence of the Negro and Solimões/Amazon Rivers, Brazil, collecting a series of Acoustic Doppler Current Profiler (ADCP) transects in different flow conditions. These data were used to investigate the morphology of the bedforms observed in that area. First, the bedforms were mostly classified as large and very large dunes according to Ashley et al. (1990), with an observed maximum wavelength and wave height of 350 and 12 m, respectively. Second, a comparison between low flow and relatively high flow conditions showed that wavelength and wave height increased as the river discharge increased in agreement with previous literature studies. Third, the lee side angle was consistently below 10°, with an average value of about 3.0°, without flow separation confirming past findings on low-angle dunes. Finally, a comparison between the bedform sizes and past literature studies on large rivers suggested that while several dunes were in equilibrium with the flow, several largest bedforms were found to be probably adapting to discharge changes in the river.

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“…where d 84 is the bed grain diameter such that 84% are finer. From Nordin et al (1977), different values for d 84 were used for the Negro, the Solimo ˜es, the confluence, and the Amazon rivers.…”

Section: Key Observations On Sediment Transportmentioning

confidence: 99%

A field study of the confluence between Negro and Solimões Rivers. Part 1: Hydrodynamics and sediment transport

Gualtieri

Filizola

Oliveira

et al. 2017

Comptes Rendus. Géoscience

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Particle size of sediments collected from the bed of the Amazon River and its tributaries in June and July 1976

Cited by 8 publications

References 1 publication

Prediction of depth‐integrated fluxes of suspended sediment in the Amazon River: particle aggregation as a complicating factor

Prediction of depth‐integrated fluxes of suspended sediment in the Amazon River: particle aggregation as a complicating factor

Bedform Morphology in the Area of the Confluence of the Negro and Solimões-Amazon Rivers, Brazil

A field study of the confluence between Negro and Solimões Rivers. Part 1: Hydrodynamics and sediment transport

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