Ch. 17] ABSECON INLET, NEW JERSEY 313 



solid-dam plans on the harbor as a whole, that the method that added 

 a sufficient portion of the Back River tidal prism to Front River to 

 increase appreciably the velocities in lower Front River would also 

 have the effect of decreasing the tidal prism of the harbor. A decrease 

 in tidal prism might cause shoaling in areas of the harbor not subject 

 to shoaling at present, because such decrease would be accompanied by 

 decreases in mean current velocities of a magnitude proportional to the 

 decrease in tidal prism. It was recommended, therefore, that it first 

 be attempted to reduce shoaling in lower Front River by improving 

 the hydraulic efficiency of the navigation channel and then, if addi- 

 tional works are required, to install either the tide-gate or the solid- 

 dam plan, whichever effected only a slight reduction in the tidal prism 

 of the harbor. 



ABSECON INLET, NEW JERSEY 



A fourth type of sedimentation problem, and one encountered fre- 

 quently by the coastal districts of the Corps of Engineers, is that of 

 shoaling of the entrance channel to a bay or estuary by the alongshore 

 or littoral drift of sand, as influenced by the combined action of waves, 

 tidal currents, and littoral currents. As an example of the investiga- 

 tion of this type of problem by means of hydraulic models, the study 

 of Absecon Inlet, New Jersey, has been selected. 



Absecon Inlet (see Fig. 9) is located on the coast of New Jersey 

 and lies between Brigantine Beach on the north and Atlantic City 

 Beach on the south. At the time of the model study a 400- by 20-foot 

 channel was maintained through the inlet to afford access to the port 

 of Atlantic City by coastal vessels and pleasure and fishing craft. The 

 entrance channel was subject to very heavy shoaling and required fre- 

 quent maintenance dredging; furthermore, because it was exposed 

 to the direct attack of ocean waves, both navigation and dredging op- 

 erations were extremely hazardous during winter months. 



The predominant littoral drift at Absecon Inlet is from northeast to 

 southwest, the sand being moved along Brigantine Beach, across the 

 inlet, thence southwesterly along the Atlantic City Beach. This sand 

 provides a continuous supply of material to the Atlantic City Beach 

 and, since maintenance of the stability of this beach was of utmost im- 

 portance, it was essential that a plan of improvement designed to re- 

 duce shoaling of the entrance channels should not reduce the supply of 

 sand from beyond the inlet channel. 



The model used for this study reproduced approximately 110 square 

 miles of the Atlantic Ocean and Absecon Inlet to a point slightly above 



