144. The effects of Plan 1 on tidal currents were mainly local and 

 caused by sand-tightening of the south jetty. Velocities at the end of the 

 jetties and at tide Gage 1 increased by approximately 10 percent. There were 

 no significant changes in velocities at the throat of the inlet, including 

 Range 1 and the Fort Clinch area. 



145. Model B predicts an increase in deposition and erosion rates be- 

 tween sta -97+76 and sta 325+00 from base to Plan 1 . For the reach of channel 

 between sta -80+00 and sta 325+00, the predicted yearly shoaling volumes are 

 475,000 and 788,000 cu yd/year for base and Plan 1, respectively, or an in- 

 crease of 66 percent for Plan 1 . 



146. On the basis of Model B results and all other available informa- 

 tion, recommendations on advance maintenance dredging were made for different 

 reaches of the navigation channel (Table 5) • 



147. For the length of channel between sta -97+76 and sta 325+00, if 

 only the rectangular portion of the planned channel cross section is consid- 

 ered, the total dredging volume for advance maintenance in accordance with 

 Model B recommendations represents a savings of approximately 630,000 cu yd or 

 nearly 27 percent compared to the dredging volume for a channel with 3-ft 

 advance maintenance throughout according to Plan 1. 



148. In summary, the study successfully accomplished all the study 

 objectives, as set forth in paragraph 3, "Purpose," except for the determina- 

 tion of waves and wave-induced currents under plan conditions. The numerical 

 models for these processes were not rerun, as originally planned, in order to 

 meet the urgent needs of the sponsor. 



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