Observations of Time-Dependent Bedform Transformation in Combined Wave-Current Flows

M. E. Wengrove*, D. L. Foster, T. C. Lippmann, M. A. de Schipper, J. Calantoni

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

13 Citations (Scopus)
56 Downloads (Pure)

Abstract

Although combined wave-current flows in the nearshore coastal zone are common, there are few observations of bedform response and inherent geometric scaling in combined flows. Our effort presents observations of bedform dynamics that were strongly influenced by waves, currents, and combined wave-current flow at two sampling locations separated by 60 m in the cross shore. Observations were collected in 2014 at the Sand Engine mega-nourishment on the Delfland coast of the Netherlands. The bedforms had wavelengths ranging from 14 cm to over 2 m and transformed shape and orientation within, at times, as little as 20 min and up to 6 hr. The dynamic set of observations was used to evaluate a fully unsteady description of changes in the bedform growth with the sediment transport continuity equation (Exner equation), relating changes in bedform volume to bedload sediment transport. Analysis shows that bedform volume was a function of the integrated transport rate over the bedform development time period. The bedform development time period (time lag of bedform growth/adjustment) is important for estimating changes in bedform volume. Results show that this continuity principle held for wave, current, and combined wave-current generated bedforms.

Original languageEnglish
Pages (from-to)7581-7598
Number of pages18
JournalJournal of Geophysical Research: Oceans
Volume123
Issue number10
DOIs
Publication statusPublished - 1 Jan 2018

Keywords

  • bedform growth
  • combined wave-currents
  • field observations
  • ripples
  • sediment continuity

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