A Morphological Comparison of Narrow, Low-Gradient Streams Traversing Wetland Environments to Alluvial Streams

Jurmu, Michael C.

doi:10.1007/s00267-002-2681-z

Cited by 17 publications

(14 citation statements)

References 29 publications

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“…The location and spacing of identified bedforms reported in this paper matched well with visually mapped geomorphic units (including pools and riffles) in the Snake River and their calculated spacing (average of 5.9 channel widths) (Miller et al, 2002). Similarly, the average riffle spacing reported in this paper matches well with previous work that used the bedform differencing technique, including the average riffle spacing of 4.7-7.3 channel widths in small rivers (O'Neill and Abrahams, 1984;Jurmu, 2002) and the average riffle spacing of 5.5-8.8 channel widths in the much larger lower Mississippi River (Harmar et al, 2005). The differences in average riffle spacing among these studies that applied the bedform differencing technique likely result from the inherent variability in channel morphology within and among different rivers and from the method used for selecting the threshold value that delineates bedforms.…”

Section: Discussionsupporting

confidence: 87%

Bedform morphology of salmon spawning areas in a large gravel-bed river

Hanrahan

2007

Geomorphology

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Section: Discussionsupporting

confidence: 87%

Bedform morphology of salmon spawning areas in a large gravel-bed river

Hanrahan

2007

Geomorphology

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“…Their cross-sectional asymmetry results in higher b values because the rising stage fills a wider proportion of the channel bed before encountering the nearvertical channel banks. Similar channel geometries were observed in several wetland streams across North America by Jurmu and Andrle (1997) and Jurmu (2002).…”

Section: Hydraulic Controlssupporting

confidence: 67%

“…While the general morphology of freshwater peatland channels has been the focus of some research (Garofalo, 1980;Jurmu and Andrle, 1997;Jurmu 2002;Smith and Perez-Arlucea, 2004;Nanson, in press), and the effect of their unusual cross-sectional and bend morphologies on flow patterns has been documented (Nanson, 2009b), their hydraulic geometry has received only modest attention (Watters and Stanley, 1997;Tooth and McCarthy, 2004). Some data are available from tidal salt marshes (e.g., Myrick and Leopold, 1963;Ashley and Zeff, 1988;Zeff, 1988Zeff, , 1999, but, despite similarities between freshwater and estuarine peatland channel geometries, the controls on these systems are obviously very different, particularly with respect to the directions of flow and relative effectiveness of riparian vegetation in providing bank strength.…”

Section: Introductionmentioning

confidence: 99%

The hydraulic geometry of narrow and deep channels; evidence for flow optimisation and controlled peatland growth

Nanson

Huang

2010

Geomorphology

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At-a-station and bankfull hydraulic geometry analyses of peatland channels at Barrington Tops, New South Wales, Australia, reveal adjustments in self-forming channels in the absence of sediment load. Using Rhodes ternary diagram, comparisons are made with hydraulic geometry data from self-forming channels carrying bedload in alluvial settings elsewhere. Despite constraints on channel depths caused at some locations by the restricted thickness of peat, most stations have cohesive, near-vertical, well-vegetated banks, and width/depth (w/d) ratios of similar to 2 that are optimal for sediment-free flow. Because banks are strong, resist erosion and can stand nearly vertical, and depth is sometimes constrained, adjustments to discharge are accommodated largely by changes in velocity. These findings are consistent with the model of maximum flow efficiency and the overarching least action principle in open channels. The bankfull depth of freely adjusting laterally active channels in clastic alluvium is well known to be related to the thickness of floodplain alluvium and a similar condition appears to apply to these swamps that grow in situ and are formed almost entirely of organic matter. The thickness of peat in these swamps rarely exceeds that required to form a bankfull channel of optimum w/d ratio for the transport of sediment-free water. Swamp vegetation is highly dependent on proximity to the water table. To maintain a swamp-channel and associated floodplain system, the channels must flow with sufficient water much of the time; they not only offer an efficient morphology for flow but do so in a way that enables bankfull conditions to occur many times a year. They also prevent the swamp from growing above a level linked to the depth of the channel. Once the channel attains the most efficient cross section, further growth of the swamp vertically is restricted by enhanced flow velocities and limited flow depths. This means that the volume of peat in such swamps is determined by the hydraulic efficiency of their channels. The development and maintenance of the hydraulic geometry of these swamp channels is biogeomorphic and biohydraulic in nature and yet accords to the same optimising principles that govern the formation of self-adjusting channels and floodplains in clastic alluvium. At-a-station and bankfull hydraulic geometry analyses of peatland channels at Barrington Tops, New South Wales, Australia, reveal adjustments in self-forming channels in the absence of sediment load. Using Rhodes ternary diagram, comparisons are made with hydraulic geometry data from self-forming channels carrying bedload in alluvial settings elsewhere. Despite constraints on channel depths caused at some locations by the restricted thickness of peat, most stations have cohesive, near-vertical, well-vegetated banks, and width/ depth (w/d) ratios of ∼ 2 that are optimal for sediment-free flow. Because banks are strong, resist erosion and can stand nearly vertical, and depth is sometimes constrained, adjustments to discharge are acc...

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“…Their beds are comprised of sand and gravel, peat or basement material (bedrock) and they tend to exhibit slot-like cross-sections. Some research has focused on the cross-sectional and planform geometry of such organic streams (Jurmu and Andrle 1997;Jurmu 2002), however little research has examined their geometry-flow interactions and the relationship between the channels and their associated peatlands.…”

Section: Channelled Peatlandsmentioning

confidence: 99%

Altered Ecologies: Fire, climate and human influence on terrestrial landscapes: Terra Australis 32

Haberle¹,

Stevenson²,

Prebble³

2010

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terra australis 32Terra Australis reports the results of archaeological and related research within the south and east of Asia, though mainly Australia, New Guinea and island Melanesia -lands that remained terra australis incognita to generations of prehistorians. Its subject is the settlement of the diverse environments in this isolated quarter of the globe by peoples who have maintained their discrete and traditional ways of life into the recent recorded or remembered past and at times into the observable present.Since the beginning of the series, the basic colour on the spine and cover has distinguished the regional distribution of topics as follows: ochre for Australia, green for New Guinea, red for South-East Asia and blue for the Pacific Islands. From 2001, issues with a gold spine will include conference proceedings, edited papers and monographs which in topic or desired format do not fit easily within the original arrangements. All volumes are numbered within the same series. Copyright of the text remains with the contributors/authors, 2009. This book is copyright in all countries subscribing to the Berne convention. Apart from any fair dealing for the purpose of private study, research, criticism or review, as permitted under the Copyright Act, no part may be reproduced by any process without written permission. Inquiries should be made to the publisher. Among saltbush greyer than seaweed we boardwalk the yeasting waves of the old golden-perch pond. List of volumes in Terra AustralisRabbit dung dots a lake bottom dry since their coming -only once, last century, after seven inches of rain a farmer had to rescue his sheep by boat.The roo bounces down-slope, a brown branch crackling.The professor's eye, noting the local runoff and what the westerlies do, observes seas that rush in and out of a continent's middle, salt lakes spreading and emptying, hills pimpling up and down with cartoon-like speed, or gullying themselves into extinction, rainforests and deserts zipping back and forth like Tom and Jerry. A human mouse plague swiftly swarms, perhaps soon gone.Impermanent planet. Impermanent surface. All under air and water. The lunette is a wave, a dumper of sand, a collapsing tower in the mad rabbit years when its top blew off and old bones winked through, with a vault's worth of fine stone cores.Once so simply mislaid in sand, now so obligingly sluiced out to the un-subincised world that smiles at stone knives. terra australis 32Altered Ecologies: Fire, climate and human influence on terrestrial landscapes v You might as well offer your table knife to a carpenter.Cane grass and the Dreamtime's stone fight the eroding rivulets together. In today's rare downpour each lost core, or blunted scraper crowns some tiny eroding hillock, plops its anchor in the dissolving silts.The bettong whose skin took off the stone tool's edge has vanished -sacrifice to future fertility.Through the softening soil Homo sapiens's skeleton bumps up like a carp's back.Waits for the wind to shave it off in pieces.A D-section and a ti...

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A Morphological Comparison of Narrow, Low-Gradient Streams Traversing Wetland Environments to Alluvial Streams

Cited by 17 publications

References 29 publications

Bedform morphology of salmon spawning areas in a large gravel-bed river

Bedform morphology of salmon spawning areas in a large gravel-bed river

The hydraulic geometry of narrow and deep channels; evidence for flow optimisation and controlled peatland growth

Altered Ecologies: Fire, climate and human influence on terrestrial landscapes: Terra Australis 32

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