SILTATION IN DREDGED CHANNELS

A method of calculating the siltation rate in channels dredged at right angles to the main direction of flow is presented and tested against a simplified laboratory situation. The method consists of calcualting the near-bed concentration of suspended sediment within the channel by means of a semi-implicit finite-difference solution of the governing partial-differential equation for suspended sediment. The near-bed concentration is then combined with an equation for the movement of sediment along the bed of the channel in order to give the necessary siltation rate. The method also requires the depth distribution of velocity and sediment outside the channel, the velocity distribution within the channel, and the fall velocity of the sediment particles. In addition, various boundary erosion parameters and vertical diffusion coefficients must be calculated. The proposed method was applied to a laboratory flume in order to predict the sedimentation pattern within a rigid bed channel resulting from an injection of polystyrene particles into the flow. Comparison of laboratory and computed siltation rates was found to be good provided an appropriate re-entrainment coefficient was used. The re-entrainment coefficient was found to vary spatially in the laboratory tests and to be related to the presence of friction strips on the bed of the channel. Further tests are required in prototype situations in order to check the accuracy of the proposed method. However, earlier prototype work involving a horizontal sediment bed of flocculated silt and clay material indicates the potential usefulness of the proposed approach.

  • Supplemental Notes:
    • Paper E-2 from BHRA Fluid Engineering Symposium, University of Kent, Canterbury, England.
  • Corporate Authors:

    British Hydromechanics Research Association

    Cranfield MK43 0AJ, Bedfordshire,   England 
  • Authors:
    • O'CONNOR, B A
  • Publication Date: 1975-9

Subject/Index Terms

  • TRT Terms: Dredging; Silting
  • Subject Areas: Marine Transportation; Terminals and Facilities;

Filing Info

  • Accession Number: 00128425
  • Record Type: Publication
  • Source Agency: British Hydrodynamics Research Association
  • Files: TRIS
  • Created Date: Jan 14 1976 12:00AM