10 - 



X 







Reach 4 

 (average / = 9) 



Reaches 1-3 

 (average / =4) 







10 



Distance from Spit Tip -Miles 



Figure 4-51, 



Variation of y with Distance Along the Spit, 

 before Inlet Condition 



FIND: 



(a) Annual littoral drift trapped by inlet. 



(b) After-inlet erosion rate of the beach to the left of the inlet. 



(c) After-inlet nourishment needed to maintain the historic erosion 

 rate on the beach to the left of the inlet. 



(d) After-inlet nourishment needed to eliminate erosion left of the 

 inlet. 



SOLUTION : Divide the beach under study into four sand budget compart- 

 ments (control volumes called reaches) as shown in Figure 4-50a. Shore 

 perpendicular boundaries are established where important changes in the 

 littoral system occur. To identify and quantify the hefore-inlet sys- 

 tem, the continuity of the net transport rate along the spit must be 

 established. The terminology of Figure 4-43 and Table 4-13 is used 



4-136 



