Feedbacks between erosion and sediment transport in experimental bedrock channels

Joel P. Johnson, Kelin Whipple

Research output: Contribution to journalArticle

90 Citations (Scopus)

Abstract

Natural bedrock rivers flow in self-formed channels and form diverse erosional morphologies. The parameters that collectively define channel morphology (e.g. width, slope, bed roughness, bedrock exposure, sediment size distribution) all influence river incision rates and dynamically adjust in poorly understood ways to imposed fluid and sediment fluxes. To explore the mechanics of river incision, we conducted laboratory experiments in which the complexities of natural bedrock channels were reduced to a homogenous brittle substrate (sand and cement), a single sediment size primarily transported as bedload, a single erosion mechanism (abrasion) and sediment-starved transport conditions. We find that patterns of erosion both create and are sensitive functions of the evolving bed topography because of feedbacks between the turbulent flow field, sediment transport and bottom roughness. Abrasion only occurs where sediment impacts the bed, and so positive feedback occurs between the sediment preferentially drawn to topographic lows by gravity and the further erosion of these lows. However, the spatial focusing of erosion results in tortuous flow paths and erosional forms (inner channels, scoops, potholes), which dissipate flow energy. This energy dissipation is a negative feedback that reduces sediment transport capacity, inhibiting further incision and ultimately leading to channel morphologies adjusted to just transport the imposed sediment load.

Original languageEnglish (US)
Pages (from-to)1048-1062
Number of pages15
JournalEarth Surface Processes and Landforms
Volume32
Issue number7
DOIs
StatePublished - Jun 2007
Externally publishedYes

Fingerprint

sediment transport
erosion
bedrock
river
sediment
channel morphology
abrasion
energy
laboratory experiment
mechanic
bed roughness
energy flow
bedload
geography
energy dissipation
turbulent flow
river flow
flow field
mechanics
roughness

Keywords

  • Bedrock channel
  • Erosion
  • Henry Mountains
  • Laboratory flume
  • Sediment transport
  • Utah

ASJC Scopus subject areas

  • Earth and Planetary Sciences (miscellaneous)
  • Earth-Surface Processes
  • Geography, Planning and Development

Cite this

Feedbacks between erosion and sediment transport in experimental bedrock channels. / Johnson, Joel P.; Whipple, Kelin.

In: Earth Surface Processes and Landforms, Vol. 32, No. 7, 06.2007, p. 1048-1062.

Research output: Contribution to journalArticle

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