Table 3-4. Storms selected for beach- and dune-erosion calculations and source of water- 

 level data. 



Storm 



Date 



NOS Tide Gauge 



Thanksgiving Day northeaster 



November 24, 1984 



Mayport 



(No name) Northeaster 



March 11, 1989 



Fernandina 



Tropical Storm Gordon 



November 16, 1994 



St. Augustine 



Thanksgiving Day northeaster 1984. This northeaster was the most devastating erosive 

 storm to impact Brevard County in modern times. Water level (Figure E-l) was elevated through 

 several high tides during a broad peak of high waves (Figure E-2) lasting about 3 days. 

 Therefore, severe northeasters, which are slow moving and of large size, can be as or more 

 erosive than hurricanes (Larson and Kraus 1991), which are typically of smaller size and faster 

 moving. 



Northeaster of 1989. A March 1989 northeaster substantially eroded the Brevard County 

 coast, having high waves for more than 4 days through several high tides combined with storm 

 surge. See Figures E-3 and E-4. 



Tropical Storm Gordon 1994. This storm crossed the Florida Peninsula at Naples, exited at 

 Canaveral, went along the coast to North Carolina, then returned. Elevated water level 

 (Figure E-5) and high waves (Figure E-6) persisted over a relatively long duration 

 (approximately 6 days) for a tropical cyclone. 



3.4.3. Analysis of Storm-Induced Erosion at the Applegate Property 



To conduct the analysis of beach and dune erosion by multiple storms at the Applegate 

 property, the July 1983 FDEP profile survey at R-7 was selected to represent the pre-storm 



27 



conditions for the 1984 Thanksgiving Day northeaster. As discussed in Chapter 1, for the 

 period of the analysis (November 1984 to November 1994), substantial rubble on the beach berm 

 fronted the structure and upland of the Applegate property. Therefore, the upland behind the 

 structure will not notably respond to storm action, because the rubble serves as shore protection 

 or armoring, similar to, but not as efficient as, a rubble revetment or a bulkhead. The beach and 

 dune can only erode to the rubble, which was the situation after placement of the 1974/75 fill. 



Horizontal coverage offshore is coarse at 50-ft intervals, but the survey extends from landward of the dune crest to an 

 elevation of -5.89 ft NGVD. To complete the profile so that it could serve as a realistic initial condition for subjection to the 

 three storms, the December 1 993 offshore survey data for R-7 were appended from elevation -5.9 ft and translated as 

 required. After the dune-erosion calculation for each storm was completed, the resultant calculated profile, which was in 

 equilibrium with the storm, was replaced with data from the December 1993 survey from the +4-ft elevation to the seaward 

 limit of the survey data. This combination of profiles provided a realistic and consistent profile shape to serve as the next 

 initial condition for the subsequent storm. 



Chapter 3 Assessment of Coastal Change 3-17 



