Effect of river bed degradation and aggradation on transformation of alternate bar morphology

Miwa, Hiroshi; Daido, Atsuyuki; Katayama, Tomohito

doi:10.1201/9781439833896.ch52

Cited by 1 publication

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“…Elimination or reduction of bed sediment supplies due to dam construction can alter downstream ecosystem in a variety of ways. Decreased sediment supplies can result in bed incision and armouring (Williams and Wolman, ; Surian and Rinaldi, ), decreased bed mobility accompanied by decreased rates of geomorphic change (Church, ; Gaeuman et al ., ) and a decrease in bar relief (Miwa et al ., ; Venditti et al ., ).…”

Section: Introductionmentioning

confidence: 99%

High-Flow Gravel Injection for Constructing Designed in-Channel Features

Gaeuman¹

2013

River Res. Applic.

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A planned gravel bar was dynamically constructed at a river rehabilitation project site through a combination of mechanical channel reconfiguration and high‐flow gravel injection. Mechanical alterations intended to promote deposition in a target area were followed by the injection of 1570 m3 of gravel and small cobble 400 m upstream during a high‐flow dam release. This dynamic bar construction proved successful in that bed elevations increased locally by more than 1 m in the target area and a new alternate bar sequence was created nearby. Morphodynamic modelling used to plan the injection correctly identified general areas prone to deposition or scour, but did not correctly predict the magnitudes of change or resolve features at the scale of individual alternate bars. A flow perturbation induced by a constructed meander bend just upstream from the injection point may have contributed to alternate bar development. Despite the observed bar development, sediment budget calculations indicate that the quantity of gravel stored in the target reach remained constant, perhaps because of an interruption in the delivery of bed material from upstream. The estimated gravel load over the release increased steadily in the downstream direction and, at the downstream study area boundary, had attained a magnitude 4.6 times larger than the quantity of injected gravel. These results demonstrate that bedload entrainment from the channel perimeter dominated the gravel supply to downstream reaches and suggest that the gravel injection had little effect on geomorphic adjustments downstream from its target area. Copyright © 2013 John Wiley & Sons, Ltd.

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Section: Introductionmentioning

confidence: 99%

High-Flow Gravel Injection for Constructing Designed in-Channel Features

Gaeuman¹

2013

River Res. Applic.

View full text Add to dashboard Cite

show abstract

Effect of river bed degradation and aggradation on transformation of alternate bar morphology

Cited by 1 publication

References 2 publications

High-Flow Gravel Injection for Constructing Designed in-Channel Features

High-Flow Gravel Injection for Constructing Designed in-Channel Features

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