5
Conclusions
This study was designed to examine a relationship between channel area, tidal
period, tidal prism, and maximum channel velocity through the inlet. Movable-
bed model experiments were conducted to define an equilibrium area for two dif-
ferent tidal periods and two sand grain sizes. The magnitude of the areas meas-
ured provided additional data for the tidal prism versus minimum channel area
relationship in a size range slightly larger than previous laboratory data in the con-
tinuum to very large field inlets. These data may help define the tidal prism-
minimum channel cross-sectional area in the midrange region of channel size.
The following conclusions were reached:
a. Physical model simulations in the idealized inlet model facility and other
laboratory data and field data support a relationship, initially derived ana-
lytically, between an inlet equilibrium area, maximum inlet velocity, tidal
period, and tidal prism as:
Ac =
P
(2 bis)
TUm
b. Equation 2 is applicable to define equilibrium inlets that meet the
assumptions entering its derivation; namely, an inlet with a bay or lagoon
that fills uniformly (i.e., the tidal wavelength is much greater than bay
length); a sinusoidal bay tide, or nearly so; and a channel cross-sectional
area that does not change significantly during the tidal cycle. This con-
clusion was reached from noting how well the laboratory data (which rep-
resent true equilibrium inlets) was equivilent to the calculated area of
Equation 2.
c. The relationship could be applied to field data to evaluate data points that
do not define an equilibrium relationship between minimum cross-
sectional area and tidal prism. These filtered data may then be used to de-
fine new, more accurate tidal prism versus equilibrium area relationships
among all sizes of inlets, from laboratory to large field inlets.
d. Laboratory experiments conducted in this study indicate that Equation 2
is maintained for various inlet hydraulic conditions (e.g., inlet bays that
nearly fill and those so large that they have a tidal range much less than
27
Chapter 5 Conclusions
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