Table 1. Volume change per unit width of shore. 





Time 







;m /m/yr) 



Station 



between 



Volume 



changes ( 



No. 



surveys 



Zone 1^ 



Zone 2^ 



' Zone 3^ 





(yr) 



1 



4.2 



-11.1 



-18.8 



-8.7 



2 



4.3 



-6.6 



-10.6 



2.3 



3 



4.3 



-11.7 



-15.5 



-20.4 



4 



4.3 



-6.8 



-9.4 



37.2 



5 



4.3 



2.6 



1.4 



37.6 



6 



4.3 



-0.5 



-1.9 



30.0 



7 



4.3 



-6.0 



-14.8 



-3.5 



8 



6.2 



-4.8 



-9.0 



5.6 



10 



4.3 



-12.2 



-16.2 



9.6 



11 



5.8 



0.0 



-2.4 



26.9 



12 



6.3 



0.3 



-0.2 



12.0 



13 



4.2 



-16.5 



-17.9 



11.6 



18 



4.2 



-3.3 



-17.4 



18.1 



19 



4.2 



-11.5 



-20.3 



4.5 



20 



6.2 



-7.3 



-8.4 



3.7 



24 



4.2 



-0.9 



-8.0 



-2.4 



26 



4.2 



-8.7 



-10.4 



10.4 



27 



5.9 



-10.2 



-13.1 



-44.3 



29 



4.2 



0.0 



-1.9 



-65.2 



Avg. 





-6.1 



-10.3 



3.4 



Extends from dune to shore. 



2 

 Extends from shore to bottom of first longshore 



trough. 



3 



Extends over entire profile. 



For the entire study area, the total volume lost from the upper beaeh in 4 

 years (column 4, Table 1) averaged 41 cubic meters per meter. About 59 per- 

 cent of this loss reflects erosion above the water surface (column 3, Table 

 1), the remaining 41 percent occurs between the shore and the first longshore 

 bar. The net volume change summed over the entire active profile produced a 

 small positive, but statistically insignificant net gain of sediment (3 cubic 

 meters per meter of shore per year). Thus, within the overall survey area, 

 there was a volumetric balance between erosion on the inner part of the beach 

 and deposition offshore. This balance suggests that future profile adjust- 

 ments to different changes in water level may be predicted by a simple geo- 

 metric model discussed in the next section. This situation will not exist on 

 many open ocean coasts where eroded beach sands are transported landward by 

 overwash or wind, or are carried into inlets and deposited on ebb or flood 

 tidal shoals. 



IV. PREDICTION MODEL 



This section presents an idealized concept of profile adjustment, dis- 

 cusses objections and difficulties with applying the concept, and shows how 

 these difficulties are minimized for the present data set. Application of the 

 concept using actual measurements is followed by generalizations and specific 

 guidance on applying the concept to other areas of the Great Lakes. 



24 



