TY - JOUR
T1 - Particle trapping in stratified estuaries
T2 - Application to observations
AU - Jay, David A.
AU - Orton, Philip M.
AU - Chisholm, Thomas
AU - Wilson, Douglas J.
AU - Fain, Annika M.V.
PY - 2007/12
Y1 - 2007/12
N2 - Estuarine turbidity maxima (ETM) retain suspended particulate matter (SPM) through advection, settling, aggregation, and nonlinearities in bed processes, but the relative importance of these processes varies strongly between systems. Observations from two strongly advective systems (the Columbia and Fraser Rivers) are used to investigate seasonal cycles of SPM retention and the effects of very high flows. Results for the Fraser and Columbia plus literature values for 13 other estuaries illustrate the applicability of scaling parameters and the response of ETM phenomena to a range of river flow (UR) levels and tidal forcing. The most efficient trapping (represented by Trapping Efficiency E, the ratio of maximum ETM concentration to the source SPM concentration) occurs for low ratios of river flow to tidal current amplitude (UT), represented by low values of the Supply number SR. E in the Columbia is found to be maximal in a null zone where advection or tidal asymmetry (represented by Advection number A) is weak (A ∼ 0). The ratio of aggregation to disaggregation (the Floc number Θ) is maximal on neap tides, while the ratio of erosion to deposition (the Erosion number Π) is maximal on spring tides. The ratio of settling velocity to vertical mixing (Rouse number P) is relatively constant in the Columbia ETM (P ∼ 0.7), because particle settling velocity and turbulence levels adjust together. Assuming that this result applies broadly, scaling variables and data are combined to express ETM properties in terms of the friction velocity (U *), UR, and UT, allowing a considerable simplification of the parameters used to describe ETM.
AB - Estuarine turbidity maxima (ETM) retain suspended particulate matter (SPM) through advection, settling, aggregation, and nonlinearities in bed processes, but the relative importance of these processes varies strongly between systems. Observations from two strongly advective systems (the Columbia and Fraser Rivers) are used to investigate seasonal cycles of SPM retention and the effects of very high flows. Results for the Fraser and Columbia plus literature values for 13 other estuaries illustrate the applicability of scaling parameters and the response of ETM phenomena to a range of river flow (UR) levels and tidal forcing. The most efficient trapping (represented by Trapping Efficiency E, the ratio of maximum ETM concentration to the source SPM concentration) occurs for low ratios of river flow to tidal current amplitude (UT), represented by low values of the Supply number SR. E in the Columbia is found to be maximal in a null zone where advection or tidal asymmetry (represented by Advection number A) is weak (A ∼ 0). The ratio of aggregation to disaggregation (the Floc number Θ) is maximal on neap tides, while the ratio of erosion to deposition (the Erosion number Π) is maximal on spring tides. The ratio of settling velocity to vertical mixing (Rouse number P) is relatively constant in the Columbia ETM (P ∼ 0.7), because particle settling velocity and turbulence levels adjust together. Assuming that this result applies broadly, scaling variables and data are combined to express ETM properties in terms of the friction velocity (U *), UR, and UT, allowing a considerable simplification of the parameters used to describe ETM.
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U2 - 10.1007/BF02841400
DO - 10.1007/BF02841400
M3 - Article
AN - SCOPUS:40949098604
SN - 1559-2723
VL - 30
SP - 1106
EP - 1125
JO - Estuaries and Coasts
JF - Estuaries and Coasts
IS - 6
ER -