Using a set of LEO data from the vicinity of Channel Islands Harbor, 

 Balsillie (1976) showed that monthly averages of longshore current obser- 

 vations are a qualitative predictor of longshore transport. Figures 34, 

 35, and 36 are plots of monthly mean longshore current velocity versus 

 the longshore energy flux in the surf zone (U.S. Army, Corps of Engineers, 

 Coastal Engineering Research Center, 1975, eq. 4-29). The observed agree- 

 ment confirmed that the longshore current velocity data from southeast 

 Florida would also be a reasonable predictor of longshore transport. 



6. Tides. 



A summary of the hi^est observed water levels recorded (by month) at 

 Miami Beach by NOAA (National Ocean Survey) during the study period, is 

 shown in Figure 37. These data show an annual cycle with the maximum 

 highest tides occurring in October each year; the lowest tides generally 

 occurred between April and June. Harris (1963) concluded that this annual 

 cyclicity is predominately meteorological in origin. 



7. Other Observations. 



Beach ciosps were recorded for 5.3 percent of the observations at 

 Jupiter, 8.3 percent at Boca Raton, and 0.4 percent at Hollywood (one 

 observation) ; cusps were present more frequently during January through 

 April. Rip currents were observed during 12.7 percent of the observa- 

 tions at Jupiter, 7.8 percent at Boca Raton, and 6.0 percent at Hollywood. 



IV. RESULTS: BEACH SURVEYS 



Beach changes are primarily reflected as changes in beach width, slope, 

 elevation, and volume. This disciission is divided into the changes ana- 

 lyzed over short terms (between surveys) and the changes analyzed over 

 the longer seasonal and yearly terms. The term "average" used in describ- 

 ing beach changes at a locality means the average of data from all pro- 

 file lines at that locality; i.e., two at Jupiter, four at Boca Raton, 

 or two at Hollywood. 



Survey frequency was generally daily at Boca Raton (except weekends) 

 and weekly at Jupiter and Hollywood. In addition, several sets of 3 

 hourly surveys were collected through two complete tidal cycles at each 

 site. 



1. Pipe Profile Method . 



Coirparison of the pipe profile method for beach surveys with standard 

 tape and level surveying techniques shows advantages as well as disadvan- 

 tages . 



Advantages include the ease of measuring the exact set of points over 

 successive surveys of the profile lines, more rapid surveys, a minimum of 

 crew and equipment, and accurate data through the surf zone and nearshore. 

 After the installation of the pipe profile lines was completed, one person 



55 



