Free bars in rivers

In the paper we review some recent work on the mechanics of formation and development of river bars. The emphasis is placed on the instability process which leads to the spontaneous development of bars in almost straight reaches of alluvial rivers. A three dimensional formulation of the problem is presented along with a discussion on the relevant closure relationships. Results of linear and non linear theories for free bars under bedload dominated conditions are summarised. Furthermore, account is given on the effect on bar instability induced by suspended load, grain sorting and width variations. Some as yet unpublished results are also presented.

[1]  M. Tubino,et al.  Free–forced interactions in developing meanders and suppression of free bars , 1990, Journal of Fluid Mechanics.

[2]  M. Welford.  A Field Test of Tubino's (1991) Model of Alternate Bar Formation , 1994 .

[3]  M. Tubino,et al.  Finite-amplitude alternate bars , 1987, Journal of Fluid Mechanics.

[4]  G. Parker.  On the cause and characteristic scales of meandering and braiding in rivers , 1976, Journal of Fluid Mechanics.

[5]  Muneo Hirano,et al.  RIVER-BED DEGRADATION WITH ARMORING , 1971 .

[6]  A. Doelman,et al.  On the nonlinear dynamics of free bars in straight channels , 1993, Journal of Fluid Mechanics.

[7]  Gary Parker,et al.  A new vectorial bedload formulation and its application to the time evolution of straight river channels , 1994, Journal of Fluid Mechanics.

[8]  Jørgen Fredsøe,et al.  Sediment Ripples and Dunes , 1982 .

[9]  P. Blondeaux,et al.  A unified bar–bend theory of river meanders , 1985, Journal of Fluid Mechanics.

[10]  Yasuyuki Shimizu,et al.  Numerical Calculation of Bed Deformation in a Range of Resonant Wavenum ber of Meandering Channel , 1992 .

[11]  Dale I. Bray,et al.  Estimating Average Velocity in Gravel-Bed Rivers , 1979 .

[12]  F. Engelund,et al.  On the origin of meandering and braiding in alluvial streams , 1973, Journal of Fluid Mechanics.

[13]  M. Tubino.  Growth of alternate bars in unsteady flow , 1991 .

[14]  Taizo Hayashi,et al.  FORMATION OF DUNES AND ANTIDUNES IN OPEN CHANNELS , 1970 .

[15]  L. B. Leopold,et al.  River channel patterns: Braided, meandering, and straight , 1957 .

[16]  Van Rijn,et al.  Closure of "Sediment Transport, Part III: Bed Forms and Alluvial Roughness" , 1984 .

[17]  D. Mctigue.  Mixture Theory for Suspended Sediment Transport , 1981 .

[18]  Syunsuke Ikeda,et al.  Prediction of Alternate Bar Wavelength and Height , 1984 .

[19]  Marcelo Horacio Garcia,et al.  Entrainment of Bed Sediment into Suspension , 1991 .

[20]  L. Rijn.  Sediment Transport, Part II: Suspended Load Transport , 1984 .

[21]  M. Tubino,et al.  Weakly nonlinear theory of regular meanders , 1992, Journal of Fluid Mechanics.

[22]  M. Tubino,et al.  Grain sorting and bar instability , 1999, Journal of Fluid Mechanics.

[23]  T. Lisle,et al.  Formation of stationary alternate bars in a steep channel with mixed-size sediment: a flume experiment , 1991 .

[24]  Marcelo H. García,et al.  Dynamics of sediment bars in straight and meandering channels: experiments on the resonance phenomenon , 1994 .

[25]  G. Parker.  Self-formed straight rivers with equilibrium banks and mobile bed. Part 2. The gravel river , 1978, Journal of Fluid Mechanics.

[26]  Yuichiro Fujita,et al.  Studies on the Process of Development of Alternate Bars , 1985 .

[27]  J. Kennedy.  The mechanics of dunes and antidunes in erodible-bed channels , 1963, Journal of Fluid Mechanics.

[28]  A. M. Talmon,et al.  Laboratory measurements of the direction of sediment transport on transverse alluvial-bed slopes , 1995 .

[29]  Yasuyuki Shimizu,et al.  CALCULATION OF BED VARIATION IN ALLUVIAL CHANNELS , 1989 .

[30]  G. Parker.  Self-formed straight rivers with equilibrium banks and mobile bed. Part 1. The sand-silt river , 1978, Journal of Fluid Mechanics.

[31]  G. Parker.  Surface-based bedload transport relation for gravel rivers , 1990 .

[32]  J. Fredsøe.  Meandering and braiding of rivers , 1978, Journal of Fluid Mechanics.