EQUILIBRIUM NEAR-BED CONCENTRATION OF SUSPENDED SEDIMENT

A new approach is presented for calculating the equilibrium near-bed concentration of suspended sediment in an alluvial channel flow. It is formulated from the balance between bed sediment entrainment and suspended sediment deposition across the near-bed boundary. The entrainment flux is determined making use of a turbulent bursting outer-scale-based function and the flux of deposition by the product of near-bed concentrations and hindered settling velocity of sediment. A number of flume data records in the literature are analyzed to calibrate and verify this approach. The observed near-bed concentrations for the data records are obtained by first isolating the suspended load transport rate from the observed total load transport rate using Engelund and Fredsoe's bed-load formula and then equating the suspended load transport rate to the shape integration of Dyer and Soulsby. The present approach is shown to perform satisfactorily compared with the results of data analysis. It is found that the near-bed concentration is evidently dependent on sediment particle size in addition to the Shields parameter caused by skin friction. This finding seems to challenge previous relationships that simply represent the near-bed concentration as empirical functions of the purely skin-friction-related Shields parameter.

• Availability:
  • Find a library where document is available. Order URL: http://worldcat.org/oclc/8672558
• Supplemental Notes:
  • Financial support was provided by the National Natural Science Foundation of China under Grants No. 59609006 and 59890200-3 and by the Gakujutsu Frontier Program of the Promotion and Mutual Aid Corporation for Private Schools of Japan.
• Corporate Authors:

  American Society of Civil Engineers

  1801 Alexander Bell Drive
  Reston, VA  United States  20191-4400
• Authors:
  • Cao, Z Z
• Publication Date: 1999-12

Language

• English

Media Info

• Features: Appendices; Figures; References; Tables;
• Pagination: p. 1270-78
• Serial:
  • Journal of Hydraulic Engineering
  • Volume: 125
  • Issue Number: 12
  • Publisher: American Society of Civil Engineers
  • ISSN: 0733-9429
  • Serial URL: https://ascelibrary.org/journal/jhend8

Subject/Index Terms

• TRT Terms: Calibration; Channel flow; Chemical concentration; Deposition; Equilibrium (Systems); Flumes; Mathematical models; Suspended sediments; Turbulence
• Subject Areas: Highways; Hydraulics and Hydrology; I26: Water Run-off - Freeze-thaw;

Filing Info

• Accession Number: 00779720
• Record Type: Publication
• Contract Numbers: 59609006, 59890200-3
• Files: TRIS
• Created Date: Dec 27 1999 12:00AM