Particle trapping in stratified estuaries: Consequences of mass conservation

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

Research output: Contribution to journalArticlepeer-review

20 Scopus citations

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 number P, the ratio of settling velocity WS to the shear velocity U *, describes the material trapped in the ETM in terms of the local vertical balance between vertical mixing and aggregate settling. Advection number A = PΔU/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 = PU R/UT defines SPM supply and removal (UR is river flow). Changes in the estuarine inventory of SPM are described in terms of a Trapping Efficiency E, 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/Γ that describes the balance of aggregation (Φ) and disaggregation (Γ). 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.

Original languageEnglish
Pages (from-to)1095-1105
Number of pages11
JournalEstuaries and Coasts
Volume30
Issue number6
DOIs
StatePublished - Dec 2007

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