EM 1110-2-1100 (Part II)
30 Apr 02
Figure II-6-10.
Schematic diagram of flood and ebb currents outside an inlet (O'Brien 1969)
2πt
V . Vm sin
(II-6-9)
T
and bay tide can be represented as (see Figure II-6-17)
2πt
hb . ab cos
&ε
(II-6-10)
T
where g is phase lag, ab is bay tide amplitude (one-half the bay tide range), T is tide period, and t is time of
interest during the tide cycle. Also King's K1 and K2 are related to the Keulegan repletion coefficient K by
1
1
K'
(II-6-11)
K2
K1
c. Tidal prism.
(1) The volume of water that enters through the inlet channel during flood flow and then exits during ebb
flow is known as the tidal prism. If the hydraulic analysis as described above is used, then tidal prism P can
be calculated as
P ' 2 ab Ab
(II-6-12)
(2) Another technique for prism estimation can use observed velocity (or discharge Q) data. Assuming
a sinusoidal discharge in the channel and integrating over the flood or ebb portion of the tidal cycle
T Qmax
T Vm Aavg
/
P'
P'
(II-6-13)
π
π
Hydrodynamics of Tidal Inlets
II-6-13
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