INALI   02622
INSTITUTO NACIONAL DE LIMNOLOGIA
Unidad Ejecutora - UE
artículos
Título:
Morphology, flow structure, and suspended bed sediment transport at two large braid-bar confluences
Autor/es:
SZUPIANY, RICARDO NICOLÁS; AMSLER, MARIO LUIS; PARSONS, DANIEL; BEST, JAMES
Revista:
WATER RESOURCES RESEARCH
Editorial:
AMER GEOPHYSICAL UNION
Referencias:
Año: 2009 vol. 45 p. 1 - 19
ISSN:
0043-1397
Resumen:
Abstract:
[1] Midchannel bars and their associated confluences are key morphodynamic nodes
within braided rivers, with past studies having investigated the morphodynamics of smallnatural channels or laboratory models with relatively low width/depth (W/D) ratios,
typically at <10. This paper investigates the morphology, suspended bed sediment
distribution, and flow structure at two large braid bar confluences in the Río Paraná
(Argentina), wherein W/D ratios are much higher (approaching 100) than in smaller
channels. The results highlight the significant control of the cross-sectional distribution of
downstream flow velocity on confluence flow, suspended bed sediment concentration, and
morphodynamics and indicate that this factor may become progressively more significant
with increasing channel scale and W/D ratio, particularly when simple discharge (or
momentum) ratios between the incoming flows are used to explain the flow dynamics.
Additionally, secondary flow cells, often proposed to occupy a large part of the channel
width in small river channel confluences, are only identified in relatively small portions of
the channel width at these larger spatial scales. Such a restriction seems related to the
generative mechanisms of secondary flows at these higher W/D ratios, which are likely to
be dominated by turbulence generated along the mixing layer between the two flows and
topographic influences that limit the spatial extent of these effects. This paper
highlights the importance of these findings with respect to the flow and sediment
dynamics of large channel confluences.