Example Problem II-8-2 (Continued)

The distribution of high water tide elevations above mean sea level is given by Harris (1981) for a nearby location

with similar tidal response (Figure II-8-21). For this example, the traditional *joint probability method *(as described

by Harris (1981)) was used to combine high-water tide frequencies with storm surge probability expressed as

frequency of occurrence *per year*. Combined tide and storm surge probabilities for design return periods are

included in Figure II-8-21.

CURRENTS:

The north jetty will deflect a strong longshore current seaward. Therefore strong offshore-directed

currents can be expected along the north side of the jetty. Because of the local bathymetry, principally a rocky

reef parallel to shore, the current is expected to affect only the area near the jetty head. Local currents can be

estimated based on experience at similar sites (if any exist), physical modeling, and, possibly, numerical modeling.

For this example, moderate current speed is taken as 1.5 m/s and design current as 3.0 m/s. Tidal currents can

also be significant, since the tide range is fairly large. Tidal currents will affect navigation in the entrance, but are

not expected to influence jetty structural design.

Example Problem II-9-2 (Sheet 4 of 21)

II-8-38

Hydrodynamic Analysis and Design Conditions

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