structure in the lee of the step. Dye caught in the turbulent wake zone of the step
moved laterally along the step in the direction of increasing step height. This is
well illustrated by the dye concentrations in the photograph of Figure 56 where
the higher vertical step is at the bottom of the image, and the dye moved from
upper right to lower left in the photograph. The slower velocities in the turbulent
region allow more time for suspended sediments to be deposited adjacent to the
vertical cut.
There was no flow separation evident for the sloping transition (see
Figure 55), and dye injected upstream of the transition moved straight into the
dredged area without any substantial decrease in velocity as shown in Figure 57.
Consequently, deposition of suspended sediment should be less because of
decreased resident time in the harbor.
Figure 56. Photograph of flow entering dredged region over vertical transition
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Chapter 6 Impact of Dredging Planform
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