Experimental and numerical evidence for intrinsic nonmigrating bars in alluvial channels

  title={Experimental and numerical evidence for intrinsic nonmigrating bars in alluvial channels},
  author={Alessandra Crosato and Erik Mosselman and Frehiwot Beidmariam Desta and Wim S.J. Uijttewaal},
  journal={Water Resources Research},
Alternate bars in straight alluvial channels are migrating or nonmigrating. The currently accepted view is that they are nonmigrating if the width‐to‐depth ratio is at the value of resonance or if the bars are forced by a persistent local perturbation. We carried out 2‐D numerical computations and a long‐duration mobile‐bed flume experiment to investigate this view. We find that nonmigrating bars can also occur in straight channels without resonant width‐to‐depth ratio or steady local… 
Experimental and numerical findings on the long‐term evolution of migrating alternate bars in alluvial channels
Numerical simulations of long alluvial channels with constant flow rate and fixed banks show periodic vanishing of a few migrating bars at a time, occurring at regular spacing, which might hold only for certain morphodynamics conditions, which should be further investigated.
Numerical nonlinear analysis of alternate-bar formation under superresonant conditions
Local geometrical perturbations in alluvial channels can generate a pattern of alternate bars. Each bar is accompanied by a pool at the other side of the channel. This pool can decrease the strength
Interactive comment on “Morphometric properties of alternate bars and water discharge: a laboratory investigation” by Marco Redolfi et al
The formation of alternate bars in straightened river reaches represents a fundamental process of river morphodynamics that has received great attention in the last decades. It is well-established
Morphometric properties of alternate bars and water discharge: a laboratory investigation
Abstract. The formation of alternate bars in straightened river reaches represents a fundamental process of river morphodynamics that has received great attention in the last decades. It is
The Long‐Term Response of Alternate Bars to the Hydrological Regime
Migrating bars are large‐scale, alternate bedforms that often develop in channelized river reaches, as a consequence of an intrinsic instability of the erodible channel bed. Their behavior under
Experimental observations on long-term behavior of migrating alternate bars
Migrating alternate bars form in alluvial channels as a result of morphodynamic instability. Extensive literature can be found on their origin and short-term development, but their long-term
Numerical Study of Alternate Bars in Alluvial Channels With Nonuniform Sediment
Rivers typically present heterogeneous bed material, but the effects of sediment nonuniformity on river bar characteristics are still unclear. This work investigates the impact of sediment size
Multidecadal dynamics of alternate bars in the Alpine Rhine River
We report on a multidecadal analysis of alternate bar dynamics in a 41.7 km reach of the Alpine Rhine River, which represents an almost unique example of a regulated river with fixed levees, straight
Experimental meandering river with chute cutoffs
[1] Braided rivers are relatively simple to produce in the laboratory, whereas dynamic meandering rivers have not been sustained beyond initial bend formation. Meandering is theoretically explained


Simple physics‐based predictor for the number of river bars and the transition between meandering and braiding
The number of bars that form in an alluvial channel cross section can be determined from a physics‐based linear model for alluvial bed topography. The classical approach defines separators between
Alternate bars in and meandering of alluvial rivers
The paper presents a linear perturbation analysis of a horizontal two-dimensional mathematical model for the flow and bed topography in straight alluvial rivers with dominant bed-load. A sediment
Free–forced interactions in developing meanders and suppression of free bars
The coexistence of migrating alternate (free) bars, spontaneously developing in erodible channels as a result of an instability process, with steady point bars, forced by curvature in meandering
Bend theory of river meanders. Part 1. Linear development
Instability of the alternate-bar type in straight channels has long been identified as the cause of fluvial meandering. The condition of inerodible sidewalls, however, does not allow a meandering
Weakly nonlinear theory of regular meanders
Flow and bed topography in a regular sequence of meanders is shown to be strongly influenced by nonlinear effects within a fairly wide range of aspect ratios of the channel and meander wavenumbers.
Alternating bar instabilities in unsteady channel flows over erodible beds
  • P. Hall
  • Physics
    Journal of Fluid Mechanics
  • 2004
Channel flows over erodible beds are susceptible to instabilities of the coupled fluid and sediment flow equations. The most dangerous mode usually takes the form of a migrating alternating bar
The initial instability and finite-amplitude stability of alternate bars in straight channels
Instability and river channels
A linearized stability analysis of the flow of water in a channel with a loose bed and straight banks is described. It is assumed that the wavelength of the perturbations, which develop into meanders
Bed deformation in curved alluvial channels
Recent research activities at the Delft Hydraulics Laboratory and the Delft University of Technology have increased the understanding of the large-scale bed deformation in alluvial rivers with
On the cause and characteristic scales of meandering and braiding in rivers
  • G. Parker
  • Environmental Science
    Journal of Fluid Mechanics
  • 1976
A stability analysis of meandering and braiding perturbations in a model alluvial river is described. A perturbation technique, involving a small parameter representing the ratio of sediment