Coarser and rougher: Effects of fine gravel pulses on experimental step-pool channel morphodynamics

J. P.L. Johnson, A. C. Aronovitz, W. Kim

Research output: Contribution to journalArticlepeer-review

26 Citations (Scopus)


Understanding how steep mountain rivers respond to natural and anthropogenic sediment supply perturbations is important for predicting effects of extreme events (e.g., floods and landslides) and for restoring rivers to more natural conditions. Using flume experiments, we show that stabilized step-pool-like channel beds can respond to pulses of finer gravel by becoming even coarser and rougher than before. Adding finer gravel initially reduces bed roughness and also increases the mobility of previously stable bed grains. Small- and intermediate-diameter clasts are then preferentially winnowed from the bed surface, leaving behind higher concentrations of even larger clasts. Ultimately, this results in both a coarser and rougher bed. Our experiments demonstrate that steep river beds become stable through the coevolution of bed roughness and surface grain size distribution and that these morphological variables can be sensitive to the history of upstream sediment supply.

Original languageEnglish
Pages (from-to)8432-8440
Number of pages9
JournalGeophysical Research Letters
Issue number20
Publication statusPublished - 2015 Oct 28

Bibliographical note

Publisher Copyright:
© 2015. American Geophysical Union. All Rights Reserved.

All Science Journal Classification (ASJC) codes

  • Geophysics
  • Earth and Planetary Sciences(all)


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