13
10
12
10
11
10
10
10
109
8
10
7
10
6
10
Jarrett
Byrne, et al
5
10
Mayor-Mora
4
10
This study
Jarrett's equation
103
2
10
1
10
10-2
10-1
100
101
102
103
104
105
106
107
2
Mimimum Cross-sect ion Area , ft
Figure 15. Field and laboratory tidal prism and inlet minimum cross-section area
-5 0.95
plotted with Jarrett's equation (A = 5.74 10 P ) (To convert area to
square meters, multiply by 0.0929. To convert prism volume to cubic
meters, multiply by 0.0283)
Based on the discussion of the previous paragraph it would seem likely that a
regression relationship should be developed based on data that fall on the agree-
ment line. This procedure with "filtered" data would more likely define a more
accurate equilibrium area. There could then be a tidal prism-minimum cross-
sectional area relationship for the continuum of inlets, from the large to the very
small. However, this relationship would represent only inlets that satisfy the sim-
plifying assumptions of Keulegan (1967) described in Chapter 1.
The difference between wave and nonwave conditions is illustrated by Mayor-
Mora's (1973) laboratory data in Figure 16, which shows that the trend is for the
nonwave tidal equilibrium-minimum areas to be larger than tide-plus-wave condi-
tions for the same tidal prism. The smaller tide-plus-wave area would agree with
the trend of the small prototype inlets falling to the right of the equality line for
both Jarrett's relation and the relation discussed in this report. For the present
experiments, the opposite trend occurred. That is, the tide-with-wave experiments
have larger areas than tide-only experiments for a given tidal prism. The larger
cross-sectional areas for the tide-and-wave condition are attributed to the lack of
influx of beach sediment because only the inlet proper was molded in sand and
the adjacent beaches were fixed bed. The wave energy in this case contributed to
moving more sediment from the minimum area because of a deficiency of influx
of sediment from the inlet, which is typically introduced from adjacent beaches.
24
Chapter 4 Experiments and Results
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