EM 1110-2-1100 (Part II)
30 Apr 02
alongshore sediment transport analyses for the shorelines adjacent to each of the inlets, and (d) one or more
sets of inlet hydrographic surveys, each set consisting of two surveys taken at different times, thereby
allowing measurement of the volume of sediment filling within the navigation channels in the time periods
between surveys.
(7) Ebb tidal energy flux. For each inlet selected, the parameter E∆T , representing the change of ebb
tidal energy flux across the ocean bar between natural and channel conditions, was computed and fixed as
constant for the given inlet using the following equation:
2
2
4T 3 d2 & d1
qmax
E∆T
(II-6-38)
'
3π
2
2
d1 d2
where
T = tidal wave period [T]
qmax = maximum instantaneous ebb tide discharge per unit width [L3/T/L]
d2 = depth of navigation channel [L]
d1 = natural depth of ocean bar [L]
The next parameter is Ew , the average daily wave energy flux per unit width of wave crest, offshore of the
site of interest. This parameter represents the intensity of sediment transport from the adjacent beaches to
the inlet environment. Daily wave energy flux can be expressed as
ML 2
6
2
EW ' K 10 (H0 ) T
(II-6-39)
T2
where
K = constant (K = 1.769 slugs/sec in English engineering units or 0.121 Kg/sec) [M/T]
Ho = deepwater wave height equivalent to observed shallow-water wave, if unaffected by refraction and
friction [L]
T = wave period [T]
The last parameter is a depth ratio DR, which is given as
d2 & d1
DR '
(II-6-40)
d3 & d1
where
d3 = water depth where seaward tip of ocean bar meets offshore sea bottom [L]
Hydrodynamics of Tidal Inlets
II-6-59
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