E.2. Fernandina and Mayport Extreme Water Levels 



This section summarizes an analysis of extreme water levels at the Fenandina Beach, Florida, 

 and Mayport, Florida, tide gauges operated by NOS (NOS Tide Stations 872 0030 and 872 0220, 

 respectively). These are the closest long-term or primary tide stations to the Brevard County 

 beaches that provide records approximating the ocean water level at the project site. The 

 Fernandina Station is located in Cumberland Sound, St. Mary's Entrance, on the Florida-Georgia 

 border, 169 miles north of Canaveral Harbor. The Mayport Station is located in St. Johns River, 

 in Mayport (near Jacksonville), and is located about 145 miles north of Canaveral Harbor. 



The plates compiled below contain the elevations and corresponding duration in hours above 

 MSL of water levels exceeding 4.5 ft for the Fernandina Station and 3.7 ft for the Mayport 

 Stations. The plates run from 1979, the year of Hurricane David, to 1995 for Fernandina and to 

 1985 for Mayport (the end of the continuous record). Hourly water-level data were analyzed to 

 arrive at the values. The cutoffs represent extreme water levels that are likely to produce erosion 

 by allowing waves to reach the upper beach and dune. For reference, the half-tide ranges, 

 defined as half of the difference between mean high water and mean low water (the half range 

 represents the average reach of the tide above MTL or mean sea level), are 2.3 ft for Mayport and 

 3.0 ft for Fernandina. 



The plates were examined by reference to the storms compiled in Appendix C and were 

 found to indicate their presence for the years covered. Because storm-induced erosion increases 

 with increase in water level and the duration of higher water levels, the plates below give a 

 qualitative indication of storm-induced erosion potential for the given storm and year. 



Appendix E Water Levels and Waves £-5 



