there is no obvious correlation between the volume changes on the two 

 parts of the surveyed profiles. This may be an indication that most 

 sand is moving in an alongshore direction, rather than in an onshore- 

 offshore direction. The apparent lack of correlation also suggests that 

 nearshore changes are not related to beach changes, but rather are re- 

 lated to the migration of nearshore bars in and out of the area being 

 surveyed. 



Other investigators working in the area CDuane and Meisburger, 1969; 

 Raymond, 1972; Richter, 1974) have suggested that although sand can move 

 offshore from the beaches, it is unlikely to move back onshore, due to 

 the steplike configuration of the shore-parallel reefs. This might be 

 reflected by a gain in the subaqueous profiles at the expense of the 

 subaerial profiles. However, no such evidence is apparent from Figures 

 51 to 54. 



4. Hollywood . 



The beach width on the two Hollywood profiles ranged from a minimum 

 of 66 feet (20 meters) to a maximum of 130 feet (40 meters) , both occur- 

 ring in February 1973. The average berm elevation was 5.4 feet (1.6 

 meters). The average monthly foreshore slope ranged from 9° to 12°, with 

 an average slope of 11° (1 on 5.1). The maximum elevation change at any 

 station was 6.8 feet (2.1 meters) of erosion between December 1970 and 

 December 1972 at pipe 4 (north row) . This change was concurrent with a 

 subaerial beach volume loss of 9.34 cubic yards per foot (23.3 cubic 

 meters per meter) during the 2-year period. 



a. Short-Term Changes . A total of 223 sets of profile surveys was 

 made at Hollywood at an average of once each 7.4 days over the study 

 period. Plots of the cumulative change between surveys in the MSL- 

 shoreline position and in the volume change above the MSL contour are 

 presented in Appendixes F and G. 



The average change in the MSL shoreline position between weekly sur- 

 veys was approximately 5 feet in either a landward or seaward direction. 

 The average volumetric gain between weekly surveys when accretion oc- 

 curred was 0.9 cubic yard per foot (2.3 cubic meters per meter) of beach; 

 the average loss was 0.7 cubic yard per foot. 



Storm changes for three specific storms are listed in Table 4. The 

 largest volume loss between weekly surveys (-4.9 cubic yards per foot) 

 occurred on profile line I (north) between surveys on 2 and 9 December 

 1969. This corresponded to a shoreline retreat on profile line I of 8 

 feet. Profile line II (south) accreted 2.9 cubic yards per foot (7.3 

 cubic meters per meter), with a 28- foot seaward translation of the shore- 

 line over the same 7-day interval. The Lake Worth wave gage was not 

 operational during this interval. LEO data collected during the two 

 surveys do not indicate unusual wind, wave, or current conditions. 

 Breaker heights of 2 feet or less were observed at Boca Raton during 

 the period of 2 to 9 December 1969. Winds were northeast at 18 miles 



87 



