Flow resistance under conditions of intense gravel transport Journal Article uri icon



  • A study of flow resistance was undertaken in a channelized reach of the North Fork Toutle River, downstream of Mount St. Helens, Washington. Hydraulic and sediment transport data were collected in flows with velocities up to 3 m/s and shear stresses up to 7 times the critical value needed for bed load transport. Details of the flow structure as revealed in vertical velocity profiles indicate that weak bed load transport over a plane gravel bed has little effect on flow resistance. The plane gravel bed persists up to stresses ∼3 times critical, at which point, irregular bed forms appear. Bed forms greatly increase flow resistance and cause velocity profiles to become distorted. The latter arises as an effect of flows becoming depth‐limited as bed form amplitude increases. At very high rates of bed load transport, an upper stage plane bed appeared. Velocity profiles measured in these flows match the law of the wall closely, with the equivalent roughness being well represented by ks = 3D84 of the bed load. The effects noted here will be important in very large floods or in rivers that are not free to widen, such as those cut into bedrock.

publication date

  • March 1, 1992

has restriction

  • closed

Date in CU Experts

  • February 25, 2017 10:22 AM

Full Author List

  • Pitlick J

author count

  • 1

Other Profiles

International Standard Serial Number (ISSN)

  • 0043-1397

Electronic International Standard Serial Number (EISSN)

  • 1944-7973

Additional Document Info

start page

  • 891

end page

  • 903


  • 28


  • 3