### 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 language | English (US) |
---|---|

Pages (from-to) | 797-803 |

Number of pages | 7 |

Journal | Geophysical Research Letters |

Volume | 42 |

Issue number | 3 |

DOIs | |

State | Published - Feb 16 2015 |

### Fingerprint

### Keywords

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

### ASJC Scopus subject areas

- Earth and Planetary Sciences(all)
- Geophysics

### Cite this

*Geophysical Research Letters*,

*42*(3), 797-803. https://doi.org/10.1002/2014GL062900

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

Research output: Contribution to journal › Article

*Geophysical Research Letters*, vol. 42, no. 3, pp. 797-803. https://doi.org/10.1002/2014GL062900

}

TY - JOUR

T1 - Controls on the geometry of potholes in bedrock channels

AU - Pelletier, Jon

AU - Sweeney, Kristin E.

AU - Roering, Joshua J.

AU - Finnegan, Noah J.

PY - 2015/2/16

Y1 - 2015/2/16

N2 - 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.

AB - 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.

KW - bedrock channels

KW - computational fluid dynamics modeling

KW - Oregon Coast Range

UR - http://www.scopus.com/inward/record.url?scp=84925144664&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84925144664&partnerID=8YFLogxK

U2 - 10.1002/2014GL062900

DO - 10.1002/2014GL062900

M3 - Article

AN - SCOPUS:84925144664

VL - 42

SP - 797

EP - 803

JO - Geophysical Research Letters

JF - Geophysical Research Letters

SN - 0094-8276

IS - 3

ER -