The equilibrium areas after waves were run are slightly larger than the areas
measured after the tide without wave action runs. The larger area generated with
waves might be caused by increased transport capacity after wave energy is added,
thus enlarging minimum area. Because this study did not introduce littoral drift
into the inlet, which might have tended to inhibit channel enlargement when wave
action was added, this tendancy for channel enlargement with waves and tides
appears reasonable.
The relationship described by Equation 2 demonstrates its utility if a compari-
son is made of plots of Jarrett's (1976) relationship between tidal prism and area
(A = 5.74 10 -5 P 0.95) and that of Equation 2 for both field and laboratory data
(Figures 13 and 14, respectively). The agreement for small inlets (Figure 14) is
much better for Equation 2; however, some of the small field inlets (Byrne, Gam-
misch, and Thomas 1980) fall below the line of perfect fit. For the small field
inlets, this could be due to some of these inlets not being in an equilibrium state.
Byrne, Gammisch, and Thomas (1980) report that these sites "are exposed to rela-
tively weak littoral drift so disturbances from `equilibrium' may require longer
recovery times. Moreover, those systems with relatively large upland drainage
basins . . . may have periodically large freshwater outflow which temporarily en-
large the channel throat area."
1E7
1000000
100000
10000
1000
Line of perfect fit
100
10
1
0.1
0.01
0.01
0.1
1
10
100
1000 10000 100000 1000000 1E7
0.95
2
Calculated Area, 5.74E-5 * P
, ft
Figure 13. Actual versus calculated area for Jarrett's tidal prism
minimum
equilibrium area relationship
22
Chapter 4 Experiments and Results
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