per hour on 5 December and southeast at 22 miles (35 kilometers) per hour 

 on 9 December. Otherwise winds were west and northwest at 19 miles (30 

 kilometers) per hour or less. Daily Weather Maps (National Oceanic and 

 Atmospheric Administration, 1969) indicated a front passing through the 

 study area late on 7 December or early 8 December. 



The largest accretion between weekly surveys occurred on profile line 

 I between the 27 February and 6 March 1973 surveys. A volume gain of 7.8 

 cubic yards per foot (19.6 cubic meters per meter) and a shoreline advance 

 of 57 feet (17.4 meters) were computed. This accretion occurred shortly 

 after the 9 to 12 February 1973 storm. 



b. Long-Term Changes . A seasonal trend was not as apparent at Holly- 

 wood as at Jupiter and Boca Raton (Figs. 59 and 60). The average rate of 

 change of the MSL shoreline for the two profiles was 2.9 feet (0.9 meter) 

 per year in a landward direction. However, the net volume rate of change 

 for the two profiles indicated a slight gain of 0.04 cubic yard per foot 

 (0.10 cubic meter per meter) per year. 



The two profiles, which were spaced only 250 feet apart often under- 

 went changes that were opposite in sign; i.e., when profile line I was 

 undergoing a gain in shoreline position and sand volume, profile line II 

 was often eroding. When profile line II was accreting, profile line I 

 was often eroding. This suggests that sand waves were moving along the 

 shore, although more than two profile lines are needed to confirm wave- 

 lengths and direction of movement. A volumetric gain or loss on either 

 profile was generally associated with a gain or loss in the MSL shoreline 

 position on the profile. The average monthly gain or loss on the Holly- 

 wood profiles was a volume change of 0.88 cubic yard per foot (2.2 cubic 

 meters per meter) per month and a shoreline change of 5.2 feet per month. 



Monthly averages of the MSL shoreline position and sand volume for 

 an average year are plotted in Figures 61 and 62. These averages indi- 

 cate that November is the month of minimum sand in storage on the beach 

 and minimum beach width. Maximum beach volume occurs in May and Septem- 

 ber; maximum beach width in March. 



5. Three-Hourly Observations . 



Ten sets of continuous LEO observations and beach profile surveys 

 were made at 3-hour intervals through two complete tidal cycles during 

 the following periods: 4 and 5 December 1969, 8 and 9 February 1973, and 

 6 and 7 JuQe 1973 at Jupiter; 16 and 17 October 1969, 1 and 2 February 

 1973, 23 and 24 May 1973, and 18 and 19 June 1973 at Boca Raton; and 6 

 and 7 January 1970, 3 and 4 February 1973, and 30 and 31 May 1973 at 

 Hollywood. Data from three sets of these observations are summarized 

 in Figures 63, 64, and 65. Each set represents the series showing the 

 largest change in the beach profiles at the locality. 



In general, weather was relatively calm throughout most of the con- 

 tinuous observation sets, and changes in the subaerial beach profiles 

 were small. Subaqueous surveys were not included in the 3-hour ly surveys. 



88 



