Ch. 17] 



ABSECON INLET, NEW JERSEY 



315 



in the prototype were reproduced accurately. In addition, the model 

 entrance channel was dredged periodically to depths shown on proto- 

 type after-dredging surveys, and it was found that the volume of 

 maintenance dredging required in the model checked very closely with 

 the volume dredged in the prototype during the 3-year verification 

 period. This feature provided a further check on the accuracy of the 

 model adjustment in that the volume of shoaling of the entrance chan- 

 nel, plus general changes in bed configurations, was reproduced. 

 Several types of jetty plans were tested to determine their effects on 



N 



N 



Fig. 10. Absecon Inlet model study. 



channel shoaling and the stability of the Atlantic City Beach. The 

 plan selected as the best (see Fig. 10) consisted of a north jetty 8,000 

 feet long and a south jetty 800 feet long. The first 1,000 feet of the 

 north jetty was at elevation +8.0 feet MLW, the next 4,500 feet was 

 at 0.0 MLW, and the remaining 2,500 feet was at +12.0 feet MLW. 

 The low section of the jetty allowed sand to move across it and into 

 the channel, from whence the sand was moved seaward by ebb cur- 

 rents in the inlet and thence back to the Atlantic City Beach by the 

 action of waves. The south jetty sloped from elevation +9.0 feet 

 MLW at the inner end to 0.0 MLW at the outer end. A large quantity 

 of sand was trapped on the south side of this jetty, and the beaches 

 were therefore improved in that area. During initial tests of this plan, 

 it was noted that the navigation channel tended to shift to a new loca- 

 tion parallel to and approximately 800 feet south of the north jetty; 

 therefore subsequent tests involved relocating the channel in this po- 

 sition. The results of final tests of this plan indicated that mainte- 

 nance dredging in the inlet would be reduced approximately 55 percent 

 by its construction, and that the plan would have no detrimental 



