67 



Southeast Shoals have become broader and thicker, and the offshore shoals 

 have migrated slightly to the Southeast. Since 1898 accretion has occurred 

 on the southern sides of Chester and Southeast, while the shoreline between 

 these shoals and to the south of the cape has experienced erosion. This 

 seems to indicate that as sea level has risen the protected areas at False 

 Cape-Chester Shoal and Cape Canaveral -Southeast Shoal have continued to be 

 maintained, apparently at the expense of the region to the south which has 

 become more crenulate in shape due to blockage of longshore drift from the 

 north . 



Natural inlets - are the breaches between barrier islands, usually cut 

 during storms. They generally affect neighboring shorelines as they 

 migrate alongshore, which causes the updrift side to accrete and the 

 downdrift side to erode. After a natural or man-made inlet is cut, ebb 

 shoals along the mouth of the inlet grow and shunt sediment across the 

 inlet and partially maintain the supply of sand to the downdrift beach. 

 Sea level rise will tend to trigger a chain of events which could result in 

 larger shoreline retreat than would occur if the inlet were not present. A 

 rise in mean water level increases the depth and planform area of a bay and 

 increases the hydraulic efficiency of an existing inlet, thereby increasing 

 the tidal prism. An increase in tidal prism increases the velocities in an 

 inlet which in turn may deepen or enlarge the throat. The ebb shoal then 

 demands more sediment from the neighboring shorelines as the inlet grows in 

 size. Sea level rise could possibly have a beneficial effect, in that 

 dredging requirements may decrease. Circulation in bay and canal systems 

 may also improve . 



Natural tidal inlets also trap sediment in shoals on the bay side of 

 the inlet (called flood shoals). Because of the reduced wave climate in 

 the bay, these shoals are usually left behind as the inlet migrates and 

 thus become a sink for sediment. As is the case with ebb shoals, the size 

 of these shoals generally increases with the size of the inlet, and an 

 increase in inlet size due to sea level rise will tend to remove more 

 sediment from the beaches and store it in flood shoals. 



A good example of the effect of long-term sea level rise on a natural 

 inlet is Nassau Sound, Florida, shown in Fig. 6.3. Calculations of the 



