Table 8 shovs the results of the analysis with redundant variahles 

 X3 and X5 removed. This procedure restjlts in the disclosure that lag 

 periods 3 and 6, corresponding to periods of rising tide, are the most 

 influential on net deposition, and that the variahles S^, T, Hq, and a 

 are the four most influential variables in combination. 



Summary Based upon an analysis involving 12 independent variables, 



it is possible to say that the 6 most-influential variables in determining 

 net deposition on the lower foreshore are Sf, T, Hq, Uq^, a, and p, and 

 that this combination of variables expresses itself 8 to 12 and 20 to 2h 

 hours prior to the low-tide time of measurement of net deposition; i.e., 

 this combination of variables expresses itself during times of rising tide. 



Net Erosion (K^) 



Results . — Table 9 shows the results of the first stage of the analy- 

 sis. Total '^-SS-reductions for the six lag periods are considerably lower 

 than those obtained for J.^ (table 7)- Taken individually, lag periods 1 

 and 2 exert the greatest influence on net erosion of the lower foreshore, 

 as net erosion is measured at low tide after two tidal cycles. If the 

 total ^-SS-reduction values for lag periods for correlative tide stages 

 (p. 35) are added together, however, lag periods 1 and h, 2 and 5^ and 3 

 and 6 have total "^-SS-reduction values of 113-^1, 10^1.26, and 72. 60, re- 

 spectively. Thus, the variables acting during times of high tide or fall- 

 ing tides exert the greatest influence on foreshore erosion. 



It is noted that variable X12, tate of rise of still-water level, 

 shows slight percent reductions in SS during lag periods 1 and h, times 

 of falling tide level. This is due to the fact that the time of measure- 

 ment of K^ was based upon the predicted time of low water. But because 

 the actual time of low water, used in computing rj^, sometimes occurred 

 slightly before predicted low water, K-f was sometimes measured just after 

 the still-water level had begun to rise. The effect on the analysis in 

 lag periods 1 and h is believed negligible. 



The influence (table 9) of lower foreshore slope, XI, on net erosion 

 tends to be relatively uniform over the six lag periods, and amounts to 

 about one-third of its observed influence on net deposition (table 7)' 

 The only variables exceeeding slope angl£ in influence in a given lag period 

 are y\^ in lag period 3^ and U f., QC, and V in lag period 2. 



The five strongest io SS reductions by combinations of variables 

 two to six at a time are shown in tables B15-B20, and the five weakest in 

 tables B21-B26. Frequency tables of the computer output are not presented 

 for Kf . 



Discussion . --The strongest combinations of independent variables 

 taken six at a time, for the two most- influential lag periods (l and 2), 

 include Sf, Lq, Hq/L , U^^, a, p, and D (tables B15 and Bl6) . Because 

 variables Xll and Xi4 contribute also to the weakest combinations (tables 



39 



