Wandering Gravel‐bed Rivers

Desloges, Joseph R.; Church, Michael

doi:10.1111/j.1541-0064.1989.tb00922.x

Cited by 112 publications

(46 citation statements)

References 4 publications

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“…The braid index ranged from 1·36 to 1·50 and generally increased through the 54-year study period ( Figure 6B); however, this increase was small compared with changes recorded in other rivers. For example, the braid index of a wandering section of the Peace River, downstream of the W. A. C. Bennett Dam, decreased from 2·4 to 1·6 in the first 20 years following the dam's closure (Desloges and Church, 1989). The braid index of the Peace River showed 5·7 times greater change in 20 years in response to flow regulation than seen on the Renous River in 54 years of natural flows.…”

Section: Channel Pattern Dynamics Of the Renous Rivermentioning

confidence: 95%

Understanding the temporal dynamics of the wandering Renous River, New Brunswick, Canada

Burge

Lapointe

2005

Earth Surf Processes Landf

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Wandering rivers are composed of individual anabranches surrounding semi-permanent islands, linked by single channel reaches. Wandering rivers are important because they provide habitat complexity for aquatic organisms, including salmonids. An anabranch cycle model was developed from previous literature and field observations to illustrate how anabranches within the wandering pattern change from single to multiple channels and vice versa over a number of decades. The model was used to investigate the temporal dynamics of a wandering river through historical case studies and channel characteristics from field data.The wandering Renous River, New Brunswick, was mapped from aerial photographs (1945, 1965, 1983 and 1999) to determine river pattern statistics and for historical analysis of case studies. Five case studies consisting of a stable single channel, newly formed anabranches, anabranches gaining stability following creation, stable anabranches, and an abandoning anabranch were investigated in detail. Long profiles, hydraulic geometry, channel energy, grain size and sediment mobility variables were calculated for each channel.Within the Renous study area, the frequency of channel formation and abandonment were similar over the 54 years of analysis, indicating that the wandering pattern is being maintained. Eight anabranches were formed through avulsions, five were formed through the emergence of islands from channel bars and 11 anabranches were abandoned. The stable anabranch pair displayed similar hydraulic geometry and channel energy characteristics, while unstable anabranch pairs did not. The anabranch pair that gained stability displayed more similar channel energy characteristics than the anabranch pair that was losing stability (abandoning). It appears that anabranch pairs with similar energy characteristics are more stable than anabranches where these characteristics are out of balance. This is consistent with the hypothesis that anabranch pairs of similar length will be more stable than those with dissimilar lengths.

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Section: Channel Pattern Dynamics Of the Renous Rivermentioning

confidence: 95%

Understanding the temporal dynamics of the wandering Renous River, New Brunswick, Canada

Burge

Lapointe

2005

Earth Surf Processes Landf

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“…Where S V < S fmin , aggradation can also result in unstable braided and meandering patterns, characterized by what have been termed wandering rivers (see, e.g., Chang, 1979b;Bettess and White, 1983;Desloges and Church, 1989;Knighton, 1998). From the point view of energy expenditure, however, only braided rivers that result from an excess valley slope are capable of rapidly achieving stable equilibrium.…”

Section: Modes Of River Channel Planform Developmentmentioning

confidence: 99%

Least action principle, equilibrium states, iterative adjustment and the stability of alluvial channels

Nanson

Huang

2007

Earth Surf Processes Landf

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The energy based least action principle (LAP) has proven to be very successful for explaining natural phenomena in both classical and modern physics. This paper briefly reviews its historical development and details how, in three ways, it governs the behaviour and stability of alluvial rivers. First, the LAP embodies the special stationary equilibrium state of motion and so its incorporation with the principle of energy conservation explains why so many optimizing hypotheses have been proposed in fluvial geomorphology. Second, the variational approach underlying the LAP provides a more straightforward and simpler fuzzy-object orientated method for solving river regime problems than do the various complex Newtonian formulations. Third, it is shown that in fluvial systems with surplus energy the surplus can be expended with slope and/or channel geometry adjustments, with the degree of channel geometry adjustment quantified by the dimensionless numbers F for depth dominated adjustment and H for width/depth dominated adjustment. Different planforms are preferred at different energy levels, with H providing a quantitative measure of the flow's efficiency for moving sediment. In rivers with insufficient energy, the interactions of endogenous and exogenous factors are shown to be capable, in certain circumstances, of achieving a stationary equilibrium condition which acts as the attractor state. Importantly, this study describes how iterative changes enable systems to achieve such a stable equilibrium.

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“…Wandering was added as a transitional channel form between braiding and meandering that exhibits characteristics of both (Neill, 1973;Church, 1983). Wandering rivers have a complicated channel planform with long sections exhibiting multiple channel anabranches surrounding semi-permanent islands supporting mature forests, separated by single channel sections (Desloges and Church, 1989). Church (1983) indicated that multiple channels of wandering rivers are sedimentation zones that lead to lateral instability, while single channel sections are transportation zones with a stable channel form.…”

Section: Introductionmentioning

confidence: 99%

“…Wandering rivers plot below braided rivers on these graphs (Desloges and Church, 1989), while anastomosed rivers plot below meandering rivers. Slope and discharge are related to stream power, a form of channel energy, but stream power is generally greater in rivers with larger discharge, thereby limiting the usefulness of this variable.…”

Section: Introductionmentioning

confidence: 99%

Wandering Miramichi rivers, New Brunswick, Canada

Burge

2005

Geomorphology

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Wandering Gravel‐bed Rivers

Cited by 112 publications

References 4 publications

Understanding the temporal dynamics of the wandering Renous River, New Brunswick, Canada

Understanding the temporal dynamics of the wandering Renous River, New Brunswick, Canada

Least action principle, equilibrium states, iterative adjustment and the stability of alluvial channels

Wandering Miramichi rivers, New Brunswick, Canada

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