On the origin of river meanders

Werner, Philippe

doi:10.1029/tr032i006p00898

Cited by 29 publications

(17 citation statements)

References 5 publications

(4 reference statements)

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“…Accordingly, we suppose that the sediment wave emanating from the perturbation can propagate laterally by influencing the flow structure at a speed (v p ) that is proportional to v g (cf. Werner, 1951;Anderson, 1967), thus: where α is a parameter between zero and unity. The angle at which the disturbance propagates across the channel is given by the ratio (v p /v), where v is the average stream velocity, or, equivalently, by (α/Fr), where Fr is the Froude number, since Fr = v/v g .…”

Section: Characteristics Of the Positive Feedback Mechanismmentioning

confidence: 97%

A conceptual model for meander initiation in bedload‐dominated streams

Eaton

Church

Davies

2006

Earth Surf Processes Landf

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A simple analytic model is presented relating local sediment transport capacity to variance in the transverse shear stress distribution in a stream channel. The model is used to develop a physically based conceptual model for the initiation of meandering in straight, bedloaddominated streams as a result of a feedback mechanism. The feedback maximizes the crosssectional shear stress variance and -in order to achieve stability -ultimately minimizes the energy slope at repeated locations along the channel, subject to steady-state mass flux and the stability of the channel boundary. These locations develop into pools in a fully developed meandering channel; they represent attractor states wherein sediment continuity is satisfied using the least possible energy expenditure per unit length of channel. However, since the cross-sectional geometry of a pool (and the adjacent bar) is asymmetric, these attractor states are only conditionally stable, requiring strong, curvature-induced secondary circulation to maintain their asymmetry. Between two successive pools, a stream occupies a metastable, higher energy state (corresponding to a riffle) that requires greater energy expenditure per unit length of channel to transport the same volume of sediment. The model we present links processes at the scale of a channel width to adjustments of the channel sinuosity and slope at the scale of a channel reach. We argue that the reach-scale extremal hypotheses employed by rational regime models are mathematical formalisms that permit a one-dimensional theory to describe the three-dimensional dynamics producing stream morphology. Our model is consistent with the results from stream table experiments, with respect to both the rate of development of meandering and the characteristics of the equilibrium channel morphology.

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Section: Characteristics Of the Positive Feedback Mechanismmentioning

confidence: 97%

A conceptual model for meander initiation in bedload‐dominated streams

Eaton

Church

Davies

2006

Earth Surf Processes Landf

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“…The response of a stream to a local disturbance has been modelled as an oblique gravity wave (Werner, 1951) and via a pendulum analogy (Anderson, 1967). Werner (1951) derived the following equation for dimensionless oscillation wavelength:…”

Section: Flow Oscillation and Meander Initiationmentioning

confidence: 99%

Initiation of river meandering

Rhoads

Welford

1991

Progress in Physical Geography: Earth and Environment

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Meanders, or frequent sinuous reversals of channel curvature, are a fundamental characteristic of river planform. Although the cause of meandering has attracted attention since the beginning of civilization, as yet there is no completely satisfactory explanation of this phenomenon. The self-similarity of meander geometry over a wide range of scales and environmental conditions suggests that meandering reflects the influence of some general control (Davy and Davies, 1979). Various arguments have been advanced to explain why rivers meander, including dissipation of excess energy (Jefferson, 1902;Inglis, 1947), minimization of energy expenditure (Yang, 1971;Chang, 1988), and minimization of the variance in bed shear stress and boundary friction (Langbein and Leopold, 1966). These theories provide predictions that conform well with observed forms, but they are primarily teleological in nature and thus difficult to evaluate scientifically; minimization of energy or shear stress could just as easily be the result of meandering as it could the cause (Richards, 1982: 28). More important, these arguments do not describe how meanders develop.Over the past 25 years, considerable effort has been devoted to identifying the physical processes that initiate the development of meanders in straight channels. This research has focused on inter-relationships among fluid dynamics, sediment transport, bed morphology, and bank erosion; the goal is to develop a hydrodynamic explanation of meandering. Although much of this work has occurred outside geography, it has relevance to physical geographers, particularly fluvial geomorphologists, for at least two reasons. First, it relates directly to geomorphic theory concerning the basic nature of meandering rivers and their sedimentary deposits. Secondly, geomorphologists are in a position to contribute substantively to theory development because many postulates of hydrodynamic theories have not been rigorously tested in the field. The purposes of this paper are: 1) to review current hydrodynamic concepts related to meander initiation; and 2) to provide direction for future geomorphologic investigations so that they may contribute directly to theory enhancement. The approach taken here is to summarize the salient ideas embodied in various theories. For detailed reviews of mathematical formulations the reader is referred to Diplas et al. (1988) and Seminara and Tubino (1989). , at WEST VIRGINA UNIV on June 20, 2015 ppg.sagepub.com Downloaded from 128 I Flow oscillation and meander initiationThe development of a meandering stream from an initially straight channel requires retreat of the banks at regularly-spaced intervals along alternate sides of the channel. Although bank erosion is a necessary condition for meander initiation (Friedkin, 1945), it is clearly the effect of some original cause, not the cause itself (Ackers and Charlton, 1970). Because bank erosion results primarily from removal of sediment at the base of the bank by hydraulic action (Thorne and Tovey, 1981), meandering is ofte...

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“…Meandering channels are widespread phenomena and there are many theories which have tried to explain the reason behind their formation (Schoklitsch 1937;Inglis 1947Inglis , 1949Leopold and Wolman 1960;Gilbert 1884;Eaking 1910;Neu 1967;Griggs 1906;Werner 1951;Hjulstorm 1957;Friedkin 1945;Agarwal 1983;Lewin's 1976;Leliavsky 1955;Prus-Chacinski 1954;Onishi et al 1976;Shen 1983).…”

Section: Introductionmentioning

confidence: 98%

Application of remote sensing and GIS in sinuosity and river shifting analysis of the Ganges River in Uttarakhand plains

2014

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Sinuosity and river shifting analysis of the Ganges River in Uttarakhand plains between Haridwar and Balawali has been done using topographic maps and various Landsat images during 1972 to 2005. The transect method was used for the river shifting measurement. The study area consists of a stretch characterized by uneven meandering and shifting. Consequently, the adjacent areas are susceptible to frequent flooding that causes significant losses of crops, property, livestock, and human lives. During the study period, different channel patterns were observed such as straight singlechannel river, braided multi-channel river, etc. It was found that the west bank of the Ganges River was subjected to more erosion and that the river is shifting towards the west. The width of the meander belt ranged from 1 to 3.5 km with an average of about 2 km. Based on the findings of this study, it is suggested that the flood protection structures are crucial for the west bank. It is further suggested that these structures be constructed outside the meander belt of the river.

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On the origin of river meanders

Cited by 29 publications

References 5 publications

A conceptual model for meander initiation in bedload‐dominated streams

A conceptual model for meander initiation in bedload‐dominated streams

Initiation of river meandering

Application of remote sensing and GIS in sinuosity and river shifting analysis of the Ganges River in Uttarakhand plains

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