217 



Real continental shelves are likely to be a combination of both of 

 these cases; and it is likely that the response of surge to sea level rise 

 is directly related to the relative change in water depth, indicating that 

 shallow shelves will be much more affected by sea level rise. 



Wave Heights 



The influences of water depth on wave generation and bottom 

 dissipation are examined in the remainder of Sect. 5. For wave generation 

 on a sloping continental shelf, it is likely that the influence of water 

 depth will be very small, as fetch length for the wave generation will be 

 unchanged. Waves generated locally will not feel the presence of the 

 bottom at the offshore end of the shelf, and thus the generation problem is 

 simply displaced landward by the amount of shoreline recession for a 

 sloping continental shelf. 



The influence of water depth on wave dissipation will also not be 

 different for a sloping shelf, assuming that the waves are in deep water at 

 the offshore end of the continental shelf, since again the problem is 

 simply displaced landward and upward. 



If, on the other hand, the shelf length is fixed, then the wave height 

 change with water depth can be significant, as shown by the example in the 

 text. This is a very important effect, as stabilized shorelines will have 

 fixed shelf lengths. 



Research Needs 



In addition to the recommendations in Sect. 5, the most important 

 research problem is to characterize the statistics of hurricane occurrence 

 and landfall locations. If, as some hypothesize, the likelihood of 

 hurricanes will increase, then the present situation needs to be fully 

 documented. Some of this work has already been done in conjunction with 

 the Federal Emergency Management Agency-Federal Insurance Administration 

 studies for coastal counties. 



SECT. 6. INTERACTION WITH NATURAL FEATURES AND CONSTRUCTED WORKS 



The response of natural and man-made coastal structures to sea level 

 rise is the subject of this section. Natural features such as barrier 



