Breaker height during the 6 and 7 June 1973 series at Jupiter aver- 

 aged 2.7 feet (0.8 meter) (Fig. 63). The longshore current averaged 1.2 

 feet (0.37 meter) per second from the north, except for a period of flow 

 toward the north between 1500 and 2400 hours, when two observations of 

 -1.9 feet (-0.58 meter) per second were made. Almost no change was ob- 

 served on profile line I; profile line II showed a slight loss (0.6 cubic 

 yard per foot, 1.5 cubic meters per meter) coincident with the second 

 current reversal (returning to flow from the north) and high tide. This 

 was followed by a recovery on the falling tide. 



The 1 and 2 February 1973 series at Boca Raton shows the strongest 

 wave and current conditions and the largest beach changes of any of the 

 series of 3-hour observations (Fig. 64). Breakers averaging 3.7 feet 

 (1.1 meters) high generated current velocities averaging 1 foot per sec- 

 ond to the north. A shoreline migration of +30 feet (+9.1 meters), rep- 

 resenting a volume gain of 2 cubic yards per foot (5.02 cubic meters per 

 meter), occurred during a 9-hour interval on profile line I. This coin- 

 cided with a sharp drop in the longshore current velocity from -1.5 feet 

 (-0.5 meter) per second to less than -0.5 foot (-0.2 meter per second) 

 ebbtide. Shoreline and volume changes on profile lines II, III, and IV 

 were significantly smaller. 



The 6 and 7 January 1970 series at Hollywood began in a moderate 

 breeze from the southeast, with 4- foot breakers and a falling tide. By 

 the end of the series conditions were nearly calm. At the beginning of 

 the series, profile line I was eroding, while profile line II was accret- 

 ing. The maximum shoreline migration was about 5 feet on both profiles. 

 Volume changes were 0.8 cubic yard per foot (2.0 cubic meters per meter) 

 on profile line I and 0.2 cubic yard per foot (0.5 cubic meter per meter) 

 on profile line II (Fig. 65). 



A significant correlation was observed between recorded sand level 

 changes and changes in observers during those series when more than one 

 observer was used. This observer correlation was most apparent when 

 sand level was recorded to the nearest 0.5 foot. Apparent sand level 

 changes appeared to be merely cases of rounding errors and differences 

 in measurement techniques. 



V. SUMMARY 



1. Observations . 



During the 4.5-year period from January 1969 through June 1973, series 

 of littoral environment observations and beach profile surveys were made 

 at three locations along the southeast coast of Florida. Frequency of~ 

 observations ranged from once weekly to once daily to once every 3 hours. 



Prevailing winds were onshore at speeds ranging from 8 to 15 miles 

 per hour. No hurricanes or major storms occurred during the study period. 

 Gale-force winds were observed only once, at Jupiter, during the study. 

 A good correlation was found between wind velocity and direction and 

 breaker height and direction. 



95 



