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islands, shoals, and tidal inlets will be affected greatly, in large part 

 by inundation due to the sea level rise. Natural tidal inlets will be 

 affected by sea level rise principally by the increase in tidal prism due 

 to the increased planform area. If the planforra of the back bay remained 

 the same (a bay with vertical sides, which is not very common) and the 

 inlet throat were in equilibrium with the littoral drift on the shoreline, 

 then the principal effect of sea level rise would be the increased shoal 

 volumes needed to keep up with sea level rise. Therefore, there would be 

 increased shoreline erosion, but the hydraulic efficiency of the inlet 

 would remain the same. The deposition on the shoals would occur over the 

 tops of the shoals, which would not produce an areal increase in size. 



For most bays, the increase in water level will increase the bay 

 planform, by inundation and by shoreline recession due to increased wind- 

 wave activity in the bay. Therefore the inlet will increase in size. 

 Jetties that line such inlets will be subjected to not only an increased 

 risk of overtopping due the increased water level, but also an increased 

 scour at the toe of the structure or at its head. Indian River Inlet, 

 Delaware, is an example of a jettied inlet that is in jeopardy of losing 

 the jetties as a result of bottom scour due to an increased tidal prism. 



For coastal shore and harbor protection structures, sea level rise 

 may be accounted for by designing the structure initially to be modified in 

 the future to account for the intervening sea level rise . This 

 recommendation was made in the National Research Council (1987) report. 



It is probably worth noting that there are a few positive results of 

 sea level rise. For example, harbor and maintenance dredging should 

 decrease. Circulation in bay and canal systems should also improve, due to 

 the increased tidal prism. 



Research Needs 



Clearly, as stated in the text, we need to develop an adequate 

 coastal model, which will allow the long-term prediction of shoreline 

 response to the effects of waves , nearshore currents , and sea level rise . 

 This entails the improvement of our knowledge of nearshore hydrodynamics , 

 nearshore wave mechanics, and nearshore sediment transport. I strongly 



