Estuaries and Coasts

, Volume 30, Issue 6, pp 1095–1105

Particle trapping in stratified estuaries: consequences of mass conservation

  • David A. Jay
  • Philip M. Orton
  • Thomas Chisholm
  • Douglas J. Wilson
  • Annika M. V. Fain
Article

Abstract

Estuarine turbidity maxima (ETM) can retain suspended particulate matter (SPM) through advection, settling, aggregation, and nonlinearities in bed processes. We define a parameter space descriptive of ETM water column particle trapping processes through a scaling analysis of the local and integral SPM balances. There are six primary non-dimensional parameters for the large particles or aggregates that are typically trapped in an ETM. Rouse numberP, the ratio of settling velocityWS to the shear velocityU*, describes the material trapped in the ETM in terms of the local vertical balance between vertical mixing and aggregate settling. Advection numberA = PDU/UT scales the landward transport of SPM in terms of flood-ebb velocity difference (ΔU; the internal asymmetry) and maximum tidal current (UT). Supply number Sr =PUr/Ut defines SPM supply and removal (Ur is river flow). Changes in the estuarine inventory of SPM are described in terms of a Trapping EfficiencyE, a ratio of peak ETM concentration to fluvial or marine supply concentration. The effects of aggregation and disaggregation in the integral dynamic balance are quantified by a Floc number Θ = Φ/Г that describes the balance of aggregation (Φ) and disaggregation (Г). The balance between erosion and deposition at the bed is described by the Erosion number Π = Ψ/Ω, the ratio of erosion (Ψ) to deposition(Ω). The non-dimensional, integral SPM conservation equation is then used to examine steady and unsteady particle trapping scenarios, including adjustments to a change in river flow and to a neap-spring transition in salinity intrusion and stratification.

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Copyright information

© Estuarine Research Federation 2007

Authors and Affiliations

  • David A. Jay
    • 1
  • Philip M. Orton
    • 2
  • Thomas Chisholm
    • 3
  • Douglas J. Wilson
    • 3
  • Annika M. V. Fain
    • 3
  1. 1.Department of Civil and Environmental EngineeringPortland State UniversityPortland
  2. 2.Ocean and Climate Physics, LamontDoherty Earth ObservatoryColumbia UniversityPalisades
  3. 3.Department of Environmental and Biomolecular Systems, OGI School of Science and EngineeringOregon Health and Science UniversityBeaverton
  4. 4.Bonneville Power AdministrationPortland
  5. 5.Imagenex Corp.Port CoquitlamCanada
  6. 6.Philip Williams and AssociatesSan Francisco

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