2.4. Datums and Shoreline Definitions 



The position and movement of the shoreline along the project site are central to the plaintiffs' 

 claim of taking and procedures of this study. Shoreline position can be determined by two 

 methods, (l)with reference to a vertical datum, and (2) as an identifiable and interpreted 

 topographic feature formed by waves and tide (e.g., the berm crest, debris line, wet/dry boundary 

 for predicted MHW, toe of dune). In previous studies at the project site and in the present study, 

 shoreline position has been determined by both methods. Jurisdictional and legal marine 

 boundaries are defined in terms of tidal datums (the first method). Application of datums and 

 measurement methods without knowledge of the errors and data inconsistencies of each method 

 may lead to inaccurate conclusions about change in shoreline position and sand volume through 

 time. The following section describes characteristic reference datums involved in the study. 



Tidal datums as determined by the NOS at Canaveral Harbor Entrance (NOS Station 

 872 1608) are shown schematically in Figure 2-7. These datums are representative of the beach 

 directly south of the Harbor. Tidal datums will change slightly with distance moved along the 

 shore of Brevard County. The nomenclature shown in Figure 2-7 is discussed next. 



4.17 ft. 

 3.79 ft- 



1.99 ft. 

 1.80 ft" 



0.19 ft. 

 0.00 ff 



.Mean Higher High Water (MHHW) 

 .Mean High Water (MHW) 



Mean Tide Level (MTL) 



National Geodetic Vertical 

 Datum 1929 (NGVD) 



Mean Low Water (MLW) 



Mean Lower Low Water (MLLW) 



Figure 2-7. Canaveral Harbor Entrance tidal datums to gauge zero. 



Chapter 2 Background 



2-11 



