shows net advance during this time period, supporting the independent estimate of sand 

 bypassing presented above (Figure 3-3). 



In summary, regional shoreline-change analysis shows that erosion of the natural (pre- 

 preject) beach that can be attributed to sand blockage by Canaveral Harbor occurs in a zone that 

 extends about 7,000 ft south of the south jetty (Figure 3-3). Also, FDEP beach-profile data 

 indicate net shoreline recession extending as far as 17,000 ft south of the Harbor after the 

 1974/75 beach fill was completed (Figure 3-5b). It is emphasized that the 7,000-ft erosion zone 

 pertains to the natural beach (beach prior to beach fill), and the 1 7,000-ft erosion zone pertains to 

 the beach-fill area. In other words, along the beach extending south from 7,000 to 17,000 ft 

 from the south jetty, primarily beach fill has eroded and spread since its placement in 1974/75, 

 and not the preexisting beach (prior to the fill) that was in the area. According to the present 

 study, the bypassing rate required for mitigating Harbor-induced downdrift erosion along the 

 beach from the south jetty to 7,000 ft south is 155,000 ±26,000 cy/year. 



3.4. Impact of Storms on Brevard County Beaches 



Brevard County is susceptible to erosion by tropical cyclones (hurricanes and tropical storms) 

 and extratropical storms (northeasters). The more severe storms that have impacted the project 

 coast are discussed in Chapter 2, and Appendix C gives an annotated listing of storms that have 

 been documented to cause notable erosion in recent times. Erosion of the beach and dune by 

 storms is independent of the presence of the Harbor. Therefore, at the properties of the test 

 plaintiffs, erosion caused by storms must be estimated so that it is not attributed to the Harbor. 



As seen in Figure 2-6, the number of documented erosional hurricanes and tropical storms 

 increased in the period 1947 to 1975, as compared with the periods 1899 to 1946 and 1976 to 

 1995. In particular, the frequency of storms became higher immediately after construction of 

 Canaveral Harbor, for the period 1954 to 1975 (see, also, Bodge and Savage 1992). 



The elevated water level (tide plus storm surge) accompanying more severe storms allows 

 waves to reach the dune face, causing erosion. A beach berm protects the dune from wave attack 

 and erosion by milder storms, but elevated water levels of more severe storms allow waves to 

 travel over even a wide beach to reach the dunes. Appendix D contains photographs of dune 

 scarping (a scarp is a vertical or near-vertical cut in the beach or dune produced by waves and 

 currents) both to the north and to the south of the Harbor. 



In contrast to storm-induced beach and dune erosion, which is rapid, accretion or buildup of beaches and dunes is a 

 gradual process of transport of sand from the dry beach berm to the dune during times of stronger onshore wind. Dune 

 buildup takes many years, assuming that the dunes are not disturbed and the process is left uninhibited. Along the coast 

 south of the Canaveral Harbor, construction on top of the dunes (lawns, houses, parking lots, and shore-protection 

 structures) interferes with the dune-building process. The dunes cannot grow in elevation with subsequent increase in width 

 that would increase their volume. Placement of sand fences on the upper portion of the beach adjacent to the south jetty of 

 Canaveral Harbor is a notable exception in which growth of sand dunes is promoted. A sufficient width of dry beach is 

 required, typically about 30 ft, for full development of wind-blown sand to occur. 



Chapter 3 Assessment of Coastal Change 3-13 



