capable of an adequate prediction of gross storm related erosion. In view of 

 this observation, a necessary comparison of the models must be made which 

 will assess the performance of each with respect to changes in certain of the 

 basic input parameters. Sargent and Birkemeier (1985) presented plots, 

 reproduced in Figures 18 and 19, showing predicted erosion volumes for a spe- 

 cific profile shape (5-m-high dune of infinite width) as a function of sedi- 

 ment diameter, deepwater significant wave height, and surge height. Similar 

 sensitivity plots, using a schematic representation of the same profile, are 

 presented for the Kriebel model in Figures 20 and 21. Figure 22 shows the 

 volumes of erosion computed as a function of storm duration. The shape 

 coefficient A is primarily a function of the sediment diameter; therefore, 

 Figures 18 and 21 are approximately equivalent. The limited effect of wave 

 height on the Kriebel results is readily apparent in Figure 20, particularly 

 between wave heights of 6 and 8 m. The coefficient A and the storm dur- 

 ation have a greater impact. 



102. It is difficult to compare the two models simply by examining the 

 estimated volumes of erosion which would occur as a result of a given storm 



PRE-STORM PROFILE 



0.30 0.35 0.40 



MEDIAN SEDIMENT SIZE. D„, i 



Figure 18. Relationship between erosion above surge level 



median sediment size, and deepwater wave heights for the 



Vellinga model (Sargent and Birkemeier 1985) 



59 



