The Reservoir Model simulations shown in Figure 10 give a reasonable match between measured
and predicted flood and ebb shoal volumes between 1950 and 2000. The model as calibrated for this
study agrees closely with the most recent measurements of flood and ebb shoal volumes at Sebastian
Inlet, but under predicts volumes determined for the late 1980's (Fig. 10) However, the calculations
and measurements are in agreement for the past decade with respect to the overall impact of sand
bypassing. Topographic data indicate a slight decrease in ebb and flood shoal volumes since 1989
(Table 1), whereas the model indicates a decrease in the rate of flood shoal growth. The model
simulation shown in Figure 10 includes sediment volume removed from the sand trap during the
model run to simulate sand-bypassing projects conducted between 1972 and 1999. Figure 11
illustrates shoal evolution without the prescribed of sand bypassing from the Sebastian Inlet sand
trap. In this case, the volume of the flood shoal sharply increases, reflecting both the additional sand
volume in the system. This result is expected under the assumption of flood-dominant sand
transport with the main inlet channel (pathway C in Fig. 8) of the Reservoir Model as applied to
Sebastian Inlet.
Fig. 11. Reservoir Model results without bypassing from Sebastian Inlet sand trap.
CONCLUSIONS
The Tidal Inlet Reservoir Model has been adapted to a realistic situation with a more complex
system of sediment transport paths than in previous applications (Kraus 2000; Militello and Kraus
2001). In particular, seasonal and episodic reversals in longshore drift can be simulated together
with bypassing of prescribed sand volumes. The model is applicable to investigation and
verification of beach and inlet morphology responses to sand management plans. The model can
also serve as a predictive tool to provide insight concerning possible consequences of removing sand
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Zarillo et al.
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