Qe avg = ^l(e 1/2 t r S2) 



4/5 



(13) 



where 



Qe avg = average erosion for a particular area, m^/m 



g = acceleration of gravity, m/sec 2 



t r = rise time (the time required to reach the peak surge 

 level) , sec 



S = peak storm surge, m 



The data from the 10 cases used to determine this equation show a remarkable 



linear fit (Figure 14). This equation is interesting because it relates the 



final erosion quantity only to the surge level and the rise time rather 



u e avg 

 (m 3 /m) 



uu 



JB 



i 



l I 



1 ' 



I— I 1 | 1 



i 



I T 







80 



















■ 



60 



• 









^^-^"» 









_ 



40 



















- 



20 



n 



-^"i 







— • 

 1 1 



i.l. 



' (g 1 ' 2 1 





i 



- 



5x10 10x10 



4/5 

 (g" 2 t f S 2 ) (m 3 /m) 



15x10 



Figure 14. Relationship between measured average net erosion 

 Qe avg and the factor (g 1 / 2 t r S 2 ) (Balsillie 1986) 



than to grain size, beach slope, offshore features, or wave height. Unlike 

 the Kriebel and Vellinga models, since the profile does not adjust to 

 equilibrium based on a balance between erosion and deposition, successive 

 similar storms will produce the same amount of erosion. As in the Vellinga 

 model, the peak surge is most important. The duration is incorporated 

 through use of the rise time, which correctly reduces the erosion potential 

 of fast moving storms. 



89. Since for a particular purpose the model of Balsillie (1985a) was 



44 



