TY - JOUR
T1 - Comparing calculated and observed vertical suspended-sediment distributions from a Hudson River Estuary turbidity maximum
AU - Orton, P. M.
AU - Kineke, G. C.
PY - 2001
Y1 - 2001
N2 - Suspended-sediment concentrations calculated using a vertical suspended-sediment distribution equation were compared to observations from a field study of the lower turbidity maximum of the Hudson River Estuary. At four stations, an instrumented tripod measured vertical profiles of suspended-sediment concentration, current velocity, salinity and temperature through a tidal cycle. Bed and suspended-sediment samples were also analysed to determine inorganic sediment size distributions. Velocities were as high as 1·3 ms−1, with suspended-sediment concentrations up to 2000 mg 1−1. When a well-defined pycnocline existed, cross-isopycnal mixing was strongly damped (based on the gradient Richardson number). Suspended-sediment profiles were calculated with a stratification-modified Rouse equation, using (1) reference concentrations measured at 20 cm above the bed, (2) estimates of shear velocity based on the quadratic stress law, and (3) a constant sediment settling velocity of 0·22 cm s−1. Differences between mean calculated and observed total suspended load for each station were - 17, 7, 14 and 58%, respectively. An uncertainty analysis revealed that the two parameterizations most likely to account for differences of this magnitude were those used for settling velocity and stratification. Best results were found when substituting a power law relationship for settling velocity based on suspended-sediment concentration. This demonstrates the improvement which a power law formulation can provide over the commonly used constant ws parameterization in fine sediment environments.
AB - Suspended-sediment concentrations calculated using a vertical suspended-sediment distribution equation were compared to observations from a field study of the lower turbidity maximum of the Hudson River Estuary. At four stations, an instrumented tripod measured vertical profiles of suspended-sediment concentration, current velocity, salinity and temperature through a tidal cycle. Bed and suspended-sediment samples were also analysed to determine inorganic sediment size distributions. Velocities were as high as 1·3 ms−1, with suspended-sediment concentrations up to 2000 mg 1−1. When a well-defined pycnocline existed, cross-isopycnal mixing was strongly damped (based on the gradient Richardson number). Suspended-sediment profiles were calculated with a stratification-modified Rouse equation, using (1) reference concentrations measured at 20 cm above the bed, (2) estimates of shear velocity based on the quadratic stress law, and (3) a constant sediment settling velocity of 0·22 cm s−1. Differences between mean calculated and observed total suspended load for each station were - 17, 7, 14 and 58%, respectively. An uncertainty analysis revealed that the two parameterizations most likely to account for differences of this magnitude were those used for settling velocity and stratification. Best results were found when substituting a power law relationship for settling velocity based on suspended-sediment concentration. This demonstrates the improvement which a power law formulation can provide over the commonly used constant ws parameterization in fine sediment environments.
KW - Aggregation
KW - Hudson River
KW - Sediment transport
KW - Stratification
KW - Tidal estuaries
KW - Turbidity maximum
UR - http://www.scopus.com/inward/record.url?scp=0034977575&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0034977575&partnerID=8YFLogxK
U2 - 10.1006/ecss.2000.0747
DO - 10.1006/ecss.2000.0747
M3 - Article
AN - SCOPUS:0034977575
SN - 0272-7714
VL - 52
SP - 401
EP - 410
JO - Estuarine, Coastal and Shelf Science
JF - Estuarine, Coastal and Shelf Science
IS - 3
ER -