Controls on the geometry of potholes in bedrock channels

Jon Pelletier, Kristin E. Sweeney, Joshua J. Roering, Noah J. Finnegan

Research output: Contribution to journalArticle

12 Citations (Scopus)

Abstract

Potholes (circular depressions carved into bedrock) are the dominant roughness elements in many bedrock channels. Here we show, using data from previous studies and new data from the Smith River, Oregon, that pothole depths increase in proportion to both the mean pothole radius (such that the most common pothole depth-to-radius ratio is 2) and the diameter of the largest clasts episodically stored in potholes. We present a theory for these observations based on computational fluid dynamics and sediment transport modeling of vortices in cylindrical cavities of different shapes and sizes. We show that the shear stress at the bottom of a pothole (which controls the rate of pothole growth) is maximized for potholes with a depth-to-radius ratio of approximately 1 and decreases nonlinearly with increasing depth-to-radius ratio such that potholes with depth-to-radius ratios larger than 3 are uncommon. Our model provides a mechanistic explanation for pothole shapes and sizes.

Original languageEnglish (US)
Pages (from-to)797-803
Number of pages7
JournalGeophysical Research Letters
Volume42
Issue number3
DOIs
StatePublished - Feb 16 2015

Fingerprint

bedrock
geometry
radii
sediment transport
computational fluid dynamics
clast
rivers
shear stress
roughness
vortex
proportion
cavity
vortices
cavities
river
modeling

Keywords

  • bedrock channels
  • computational fluid dynamics modeling
  • Oregon Coast Range

ASJC Scopus subject areas

  • Earth and Planetary Sciences(all)
  • Geophysics

Cite this

Controls on the geometry of potholes in bedrock channels. / Pelletier, Jon; Sweeney, Kristin E.; Roering, Joshua J.; Finnegan, Noah J.

In: Geophysical Research Letters, Vol. 42, No. 3, 16.02.2015, p. 797-803.

Research output: Contribution to journalArticle

Pelletier, Jon ; Sweeney, Kristin E. ; Roering, Joshua J. ; Finnegan, Noah J. / Controls on the geometry of potholes in bedrock channels. In: Geophysical Research Letters. 2015 ; Vol. 42, No. 3. pp. 797-803.
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