PART III: VERIFICATION AND BASE CONDITION TESTS 



Tides 



72. Astronomical tides are the primary driving force for currents 

 within St. Marys Inlet; they also contribute significantly to the ocean cur- 

 rents in the study area. WIFM is used to compute the currents for an average 

 tide range in order to supply the sediment transport model with a time-series 

 of depth-averaged horizontal velocity fields covering one tidal cycle 

 (12.42 hr for the semidiurnal tide at Kings Bay). 



Verification 



73. Bathymetry. Most of the bathymetry and topography information used 

 to define the grid cell elevations in Grid 1 (Figure 3) came from NOS nautical 

 charts 11488, 11502, and 11503. Detailed soundings taken by the US Army Engi- 

 neer District, Jacksonville (CESAJ) , in June 1982 provided bathymetry for the 

 navigation channels. All depths in the grid were referenced to mlw, and a 

 datum difference of 3.0 ft between mlw and mean sea level (msl) was used. The 

 maximum water depth in Grid 1 was 66 ft mlw. 



74. Prototype data. The prototype tide data used to calibrate and 

 verify WIFM in this study consisted of tidal elevations and currents. Fig- 

 ure 10 shows the locations of the tide and velocity gages deployed in the 

 Kings Bay study area. Tide data were collected by the United States Geologi- 

 cal Survey (USGS) and CEWES between September and December 1982. Currents 

 were measured along ranges 1-4 (Figure 10) on 10 November 1982, and along 

 ranges 5-7 on 12 November 1982. These surveys recorded approximately one 

 tidal cycle. At each range, currents were measured at three stations: A, B, 

 and C. At each station, velocities were measured at the surface, middepth, 

 and close to the bottom. Only ranges 1-4 lay within the bounds of the compu- 

 tational grids, so ranges 5-7 were not used in this report. These current 

 measurements were accurate and error-free, so they were used by WIFM in veri- 

 fication. The details of the prototype tide and current data collection 

 effort are reported by Granat et al. (in preparation). 



75. Plates 1-4 show the measured tides at Gages 1-4 of Figure 10 for 

 November 1982. The mean long-term tide ranges, as given by the 1982 NOS Tide 

 Tables, vary between 5.8 ft (St. Marys Entrance, north jetty) and 6.0 ft 

 (Fernandina Beach, Amelia River). The measured tide data for the range survey 



44 



