considerable distances offshore. Figure 4-60 is an example of an inlet on the 

 gulf coast of Florida where the ebb-tidal delta extends 6.4 kilometers (4 

 miles) offshore. Dean and Walton (1973) attribute the large extent of this 

 offshore delta to the relatively low amount of incoming wave energy expended 

 on the ebb delta to move the sand shoreward. 



SCALE 



(AFTER DEAN AND WALTON. 19731 



Figure 4-60. Ebb-tidal delta showing volumes accumulated in outer shoals 

 adjacent to Boca Grande Inlet, Florida (low-energy shoreline). 



Normally, three major forms of sediment accumulation are associated with 

 ebb-tidal deltas (see Fig. 4-61): 



(a) Asymmetric svash bars, oriented landward and formed by uave 

 action, which form a broken semicircle around the perimeter of the ebb- 

 tidal delta and sometimes meet the shore obliquely on either side of the 

 inlet. Swash bars are essentially sediment masses arrested from the 

 general longshore drift system. They form at the inlets because of a 

 combination of the influence of (1) the ebb-tidal currents, which deposit 

 the main lobe of the ebb-tidal delta, and (2) vave refraction around the 

 lobe, which tends to slow down, or halt, the transport of sand past the 

 inlet. 



(b) Channel margin linear sand bars that trend perpendicular to shore 

 and parallel to the main channel. 



4- 149 



