For the three sites, there was a systematic measured decrease in the 

 severity of the wave climate, from north to south, as well as a decrease 

 in the magnitude of beach changes from north to south (Figs. 66, 67, and 

 68). Breaker heights averaged 2.8 feet at an average approach direction 

 from 2.9° to the north of shore-normal at Jupiter, 2.0 feet from a near- 

 normal shoreline approach at Boca Raton, 1.6 feet feet at an average 

 approach direction from 0.6° to the south of shore-normal at Hollywood. 

 Direction data may be observer-biased toward larger angles from shore- 

 normal (see Fig. 14) . It is concluded that this systematic change is a 

 result of the sheltering effect of the Bahamas. 



Net longshore current speed increased with an increasing breaker 

 angle from the shore-normal approach. Average longshore current speed 

 (nondirectional) decreased from a maximum of 0.93 foot per second at 

 Jupiter, to 0.92 foot per second at Boca Raton, and 0.81 foot per second 

 at Hollywood. 



The greatest fluctuation in width of the three beaches (50 to 180 

 feet) was observed at Jupiter. Boca Raton displayed the least fluctua- 

 tion, 80 to 131' feet, as a result of the natural stabilizing effect from 

 the coquina ledge occurring in the intertidal zone. Beach width at Holly- 

 wood ranged from 66 to 130 feet. 



2. Seasonal Changes . 



The lowest waves at all three sites occur during the summer months 

 and arrive from the southeast; the higher waves occur during the winter 

 months and arrive from the northeast. Net longshore current speed and 

 direction are directly related to breaker direction. Breakers approach- 

 ing from the northeast generate currents flowing toward the south; break- 

 ers approaching from the southeast generate currents flowing toward the 

 north. 



Beach changes are seasonal at the three localities, but are reversed 

 at Boca Raton. At Jupiter and Hollywood, beaches are narrowest in the 

 winter with the least amount of sand in storage. At Boca Raton, which 

 is 40 miles south of Jupiter and 25 miles north of Hollywood, the beach 

 is widest in the winter with the greatest amount of sand in storage; the 

 maximum beach loss rates occur during the summer months. Seasonal beach 

 changes are two to three times the magnitude of year-to-year changes. 

 The magnitude of beach changes through a tidal cycle was of the same 

 order as the observed seasonal changes. 



3. Transport . 



Prediction of longshore transport rates at each site, using breaker 

 height and direction data, confirms a previously published southward- 

 decreasing trend. The prediction of net longshore transport rates 

 suggests a nodal zone of convergence between Boca Raton and Jupiter, 

 although this feature has not been demonstrated in other studies. 



96 



