Boca Raton Summary & Conclusions

• The beach nourishment project area has lost approximately 399,000 cubic yards of sand since 1988.  The erosion of the restored beach has slowed from a first year loss of 151,000 cubic yards to a loss of 18,700 cubic yards over the 1996-1997 study period.
• In 1988, the wave-adjusted (equilibrium) shoreline was extended approximately 150 feet seaward with the construction of the project.  Initially, the beach was constructed an additional 100 feet wider to allow for the steep construction slopes to adjust to the natural slopes.  After construction and over the first two years, sand from the beach moved offshore until the system achieved a natural (equilibrium) slope.  Almost half of the expected adjustment (45 feet) had occurred by August 1988 when the beach surveys were conducted after construction.
• In June 1997, the project beach was an average of 45 feet wider than the 1988 pre-construction beach.  The slope of the beach has reached equilibrium, and with the exception of a major storm, future shoreline retreat should be limited to primarily longshore losses.  In 1998, the beach without construction is anticipated to be an average of 35 feet wider than its pre-construction condition, assuming a retreat rate of 10 feet/year.

• Approximately 60% of the 680,000 cubic yards placed in 1998 remains in the project area.  The remaining four year post-construction beach width of 75 feet is 55% of the construction beach width, which was 137 feet on average.
• Between April/May 1998 and July 2002, shoreline recession in the southern half of the project ranged from 88 to 128 feet.  Shoreline recession in the northern half (R-206 to R-208) of the project ranged from 44 to 67 feet.  The southern half of the beach fill featured more added beach width than the northern half which was based on monitoring results from the initial fill placement in 1988.   As a result of the recession and erosion patterns, the beach width relative to the pre-project conditions is approximately uniform.  The loss of material in the southern portion of the project area was expected because of the advanced state of erosion of the beach south of the project area.  It is anticipated that nourishment of the central section of Boca Raton will slow the erosion losses.