Vertical sorting and the morphodynamics of bed-form-dominated rivers: An equilibrium sorting model

Astrid Blom, Gary Parker, Jan S. Ribberink, Huib J. de Vriend

Research output: Contribution to journalArticlepeer-review


A modeling framework is developed for taking into account the effects of sediment sorting in the morphodynamic modeling of bed-form-dominated rivers for the case of equilibrium or stationary conditions dominated by bed load transport. To this end, the Blom and Parker (2004) framework for sediment continuity is reduced to an equilibrium sorting model. The predicted equilibrium sorting profile is mainly determined by the probability density function (PDF) of bed form trough elevations and by a lee sorting function. The PDF of trough elevations needs to be known from either model predictions or measurements. A simple formulation for the lee sorting function is suggested, yet data on the avalanche mechanism down lee faces of dunes is required so as to improve the function and make it generic. The equilibrium sorting model is calibrated and verified using data from flume experiments. The agreement between the predicted and measured equilibrium sorting profiles is reasonable, although the model does not reproduce an observed coarse top layer. In a hydraulic-morphodynamic model this equilibrium sorting model may be applied instantaneously if the timescale of large-scale morphological changes is much larger than the ones of changes in vertical sorting and dune dimensions.

Original languageEnglish (US)
Article numberF01006
JournalJournal of Geophysical Research: Earth Surface
Issue number1
StatePublished - Mar 24 2006

ASJC Scopus subject areas

  • Earth-Surface Processes
  • Geophysics


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