56 MARINE FISHERIES OF NORTH CAROLINA 



Continuing our quotations from Johnson, the physiographic feature known 

 as the tidal delta that is so characteristic of the North Carolina inlets (Figure 

 25) is described. "...Debris brought by beach drifting or other longshore 

 currents is seized by the inflowing or outflowing current at the inlet and 

 transported into the lagoon or out to sea. Most of the debris is not carried 

 far before being deposited in the quieter water of the larger waterbody to 

 form a tidal delta. The typical tidal delta is wholly submerged and is double, 

 one part facing landward and representing the result of deposition in the 

 lagoon by incoming currents; the other part facing seaward and owing its 

 construction to deposition in the sea by outflowing currents. Because the 

 seaward part of the delta is exposed to the action of waves and longshore 

 currents it is commonly stunted in its growth and margined by contours of 

 simple curvature ; only that portion in the lagoon is apt to acquire appreciable 

 size and the lobate form of ordinary deltas." 



From the above it is clear that the maintenance of a new inlet and its 

 channel is often an engineering task in direct opposition to natural forces 

 which, due to storms, are highly unpredictable. Estimates that are frequently 

 made as a basis for evaluating the economic feasibility of an inlet project are 

 thus subject to error. The experience with New Inlet in Dare County illus- 

 trates this. New Inlet was closed by a storm in 1922. An unsuccessful attempt 

 was made to reopen it artificially in 1924; yet a storm accomplished the 

 reopening in a couple of days in 1932. 



According to the Corps of Engineers (1948), the usual combination caus- 

 ing the formation of a new inlet in the barrier beach off the broad North 

 Carolina sounds begins with a sudden shifting of the waters from the land- 

 ward to the seaward side of the sounds, caused by changes in wind direction 

 during infrequent cyclonic storms of great intensity. The resulting high 

 waters wash over low places in the bar and sometimes flow toward the ocean 

 for a great many hours cutting a deep gorge. The past history of inlets in- 

 dicates that the waters of Albemarle and Pamlico sounds will again carry 

 out this pattern to form additional inlets. The past also indicates that such 

 inlets will probably be filled at a later date by sand drifting along the shore. 



One characteristic of past studies considering new or modified inlets is 

 the tendency to assume that any biological effects will be beneficial. Increas- 

 ing salinity near an inlet would probably better the clam production and 

 possibly the yield of certain other fisheries products; however, harmful 

 results are not inconceivable. Certainly the popular concept, that more inlets 

 will mean increased migration of fishes into the sounds, is unfounded. The 

 concept may be true or partly true; yet there may be some detrimental 

 results. For example, if discharge of brackish water through an inlet attracts 

 fish, the addition of inlets may so reduce this factor for any given inlet as to 

 be less than the amount necessary to stimulate migration. Little or no in- 



