A General Theory of Flow in Alluvium.

Lacey, G

doi:10.1680/ijoti.1946.13786

Cited by 45 publications

(26 citation statements)

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“…are all very close to 'regime theory' established typically by Lacey (1929Lacey ( , 1933Lacey ( , 1946Lacey ( , 1958 and by Simons and Albertson (1960). In many circumstances, sediment discharge Q s is unknown and channel slope is used as an alternative.…”

Section: Averaged Optimum Channel Geometry Relationshipssupporting

confidence: 86%

A stability criterion inherent in laws governing alluvial channel flow

Huang

Nanson

2002

Earth Surf Processes Landf

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The stability criterion of maximum flow efficiency (MFE) has previously been found inherent in typical alluvial channel flow relationships, and this study investigates the general nature of this criterion using a wider range of flow resistance and bedload transport formulae. For straight alluvial channels, in which the effect of sediment sorting is insignificant, our detailed mathematical analysis demonstrates that a flow efficiency factor ε occurs generally as the ratio of sediment (bedload) discharge Q s to stream power ( QS) in the form of ε D Q s / ¯ (¯ D 0Ð86-0Ð88). When ε is maximized (i.e. Q s is maximized or is minimized), maximally efficient straight channel geometries derived from most flow resistance and bedload transport formulae are found compatible with observed bankfull hydraulic geometry relations. This study provides support for the use of the criteria of MFE, maximum sediment transporting capacity and minimum stream power for understanding the operation of alluvial rivers, and also addresses limitations to the direct application of its findings.

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Section: Averaged Optimum Channel Geometry Relationshipssupporting

confidence: 86%

A stability criterion inherent in laws governing alluvial channel flow

Huang

Nanson

2002

Earth Surf Processes Landf

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“…They exhibit stable channel geometries, which can be predicted with reasonable accuracy using 'regime theory' for stable canals (Lacey, 1929(Lacey, , 1933(Lacey, , 1946(Lacey, , 1958Blench, 1952Blench, , 1969Blench, , 1970Simons and Albertson, 1960) and 'hydraulic geometry' for stable river channels (Leopold and Maddock, 1953;Parker, 1979;Huang and Warner, 1995;Huang and Nanson, 1995, 1998. While these regime relationships are a response to a set of interacting factors associated with the amount of water and sediment in transport, and a range of additional factors such as local vegetation, sediment texture and regional gradients, they can be represented empirically simply and approximately in the following form:…”

Section: Clarifying the Confusion Of Multiple Extremal Hypothesesmentioning

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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“…Lacey modified his equations in the light of new regime data (Lacey, 1947(Lacey, , 1958, which included substituting bankfull width and mean depth in place of wetted perimeter and hydraulic radius, respectively. The complete set of revised Lacey equations were presented by Mahmood and Shen (1971, p. 30-12).…”

Section: Development Of Cross Section Regime Equationsmentioning

confidence: 99%