Kp. Black et Gd. Parry, Entrainment, dispersal, and settlement of scallop dredge sediment plumes: field measurements and numerical modelling, CAN J FISH, 56(12), 1999, pp. 2271-2281
Citations number
21
Categorie Soggetti
Aquatic Sciences
Journal title
CANADIAN JOURNAL OF FISHERIES AND AQUATIC SCIENCES
Entrainment, dispersal, and settlement of sediment plumes generated by scal
lop dredging were measured with an instrumented towed sled and downstream s
ensors during a series of experiments conducted in the main scallop grounds
in Port Phillip Bay in southeastern Australia. When three 36-ha experiment
al plots were subjected to closely supervised, intensive dredging by commer
cial fishers, it was found that dredges suspend a thin layer of sediment (s
imilar to 0.5 cm thick) inducing initial near-bed concentrations of 2-15 kg
.m(-3) in a billowing turbid plume. At one field site where 30% of seabed s
ediment was less than 4 phi, concentrations reduced after 30 min to about 2
% of the initial value and grain sizes decreased to a predominantly mud-siz
ed sediment with a mean size of 5-6 phi. A numerical model was developed to
depict plume transformations and settlement patterns. The model accurately
predicted patterns of sedimentation and temporal changes to suspended sedi
ment concentration and grain size distribution in the plume. By explicitly
treating local seabed grain size, current, and water column turbulence, the
model can be applied to other locations and conditions to examine suspende
d sediment concentrations and potential sediment-related impacts of scallop
dredging.