Height and wave length of alternate bars in rivers: modelling vs. laboratory experiments

Michiel Knaapen, Suzanne J.M.H. Hulscher, Huib J. de Vriend, Aart van Harten

Research output: Book/ReportReportProfessional

Abstract

Alternate bars are large wave patterns in sandy beds of rivers and channels. The crests and troughs alternate between the banks of the channel. These bars, which move downstream several meters per day, reduce the navigability of the river. Recent modelling of alternate bars has focused on stability analysis techniques. We think, that the resulting models can predict large rhythmic patterns in sandy beds, especially if the models can be combined with data-assimilation techniques. The results presented in this paper confirm this thought. We compared the wavelength and height of alternate bars as predicted by the model of Schielen et al. [14], with the values measured in several flume experiments. Given realistic hydraulic conditions R Re > 2*10³, (R the width-to-depth ratio and Re the Reynolds number), the predictions are in good agreement with the measurements. In addition, the model predicts the bars measured in experiments with graded sediment. If R Re < 2*10³, the agreement between model results and measurements is lost. Thewave height is clearly underestimated, and the standard deviation of the differences between predictions and measurements increases. This questions the usefulness of small flume experiments for morphodynamic problems.
Original languageUndefined
Place of PublicationEnschede
PublisherUniversity of Twente
Number of pages23
Publication statusPublished - 1999

Publication series

Name
PublisherUniversity of Twente

Keywords

  • METIS-125057
  • IR-21334

Cite this

Knaapen, M., Hulscher, S. J. M. H., de Vriend, H. J., & van Harten, A. (1999). Height and wave length of alternate bars in rivers: modelling vs. laboratory experiments. Enschede: University of Twente.