215 



Robert A. Dalrjmiple 



Department of Civil Engineering 



University of Delaware 



Newark, DE 19716 



GENERAL COMMENTS 



The authors have made a thorough review of the effects of sea level 

 rise on hydrodynamic factors, such as storm surges and waves, and on 

 natural coastlines and man-made structures. I feel that their analysis is 

 complete and thorough, and I agree with their conclusions. More specific 

 comments follow for each section. 



SECT. 5. STORM SURGE AND WIND-WAVE RESPONSE 



Relative sea level rise affects the heights of storm surges, the 

 height of wind- generated waves, and the reduction of wave height due to 

 bottom friction. An illustration of the magnitude of the effect is shown 

 for each. 



Storm Surge 



For the case of storm surge, the change in total water level at the 

 shoreline for a constant-depth shelf is due to two causes: the increase in 

 mean water depth, which reduces the hydrostatic response of the shelf due 

 to the applied stress; and the increase in shelf width due to inundation 

 and shoreline recession. The first of these effects can be examined by the 

 governing equation for surge at constant water depth, h^. 



dr? B 



dx (ho + r,) (A.l) 



Clearly if the water depth, hg, increases, then the water surface response 

 slope decreases, leading to the obvious fact that the storm surges on very 

 shallow shelves, such as the Gulf of Mexico, are much greater than those on 

 deeper shelves . 



It is perhaps more informative to determine relative changes in 

 variables, such as storm surge, due to sea level rise rather than the 



