Author(s): Dominguez Ruben; L. ; Szupiany; R. ; Abad; J. D. ; Farias; H. D.
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Keywords: Large meandering rivers; Flow structure; Transport sediment; Morphology and aspect ratio
Abstract: Meandering channels are one of the most common planform configurations of rivers and are the result of the complex interaction between flow dynamics, sediment transport and morphology. Several field studies have analyzed the dynamics of small rivers (width/depth< 30) rather than large river systems (width/depth> 30) ,mainly due to limitations on equipment, logistics and methodologies. In the present study, measurements of flow structure, suspended sediment transport and bed morphology are shown from a field campaign at a large meandering river (width/depth=58) .Flow structure and suspended sediment transport, was obtained by using an acoustic Doppler current profiler (ADCP) over several cross sections along the river during bankfull stage. Results show different characteristics from the ones observed in previous studies concerning small meandering rivers, such as: i) small and low intensities on secondary circulation, with lower effect on the redistribution of bed and suspended sediment along the bends, ii) different locations between cores of maximum velocity, maximum concentration and secondary circulation, indicating particular processes governing the interaction between these variables, iii) lower cross section bed slope and absence of a second secondary circulation near outer bank, suggesting particular processes of bank retreat, iv) a flat point-bar in the inner bank with lower slope near the bank and v) a reduction of the width of thalweg, that deepens in the downstream direction, this may indicate that for this river, the erosion and deposition processes are increased towards the downstream direction.
Year: 2015