EM 1110-2-1100 (Part II)
30 Apr 02
Figure II-6-47.
1988 and 1989 bathymetry of Moriches Inlet
of Oregon Inlet, North Carolina. It is based on the premise that the natural geometry of an inlet's ebb tide
delta on the ocean bar results from the integrated effects of tidal currents, wave action, and associated
sediment transport and deposition. Of particular importance is the natural elevation of the ocean bar, which
represents both the limiting elevation of sediment accumulation resulting from the influx of littoral materials
from adjacent shores and the level below which littoral sediments will collect if the ocean bar is dredged to
provide a navigation channel. Sediment accumulation should increase with increasing channel depth until
it becomes so deep that the channel traps all sediment crossing the inlet.
(2) Procedure. In order to develop a day-by-day simulation of siltation processes and dredging effects,
a procedure consisting of three main phases was developed. The phases are (a) daily littoral materials
transport volumes, (b) channel sedimentation, and (c) regression analysis.
(3) Phase I: Daily littoral materials transport volumes. It is assumed that the relative magnitude of
alongshore sediment transport can be estimated simply on the basis of wave height squared in accordance
with the relationship
2
Hi
Qi ' Qg
(II-6-34)
j Hi
n
2
i'1
where
i = number of the day during the year
Qi = littoral transport occurring on day i [L3]
II-6-56
Hydrodynamics of Tidal Inlets
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