both with similar features which appear to be waves; however, on one record 

 these features indicate the irregular bottom left after dredging. For this 

 reason, all data reduction under the hybrid method was performed by the field 

 investigators who observed conditions at the time of data collection. Also, 

 this possible misinterpretation was the reason no smoothing was done under the 

 automated method . 



The data quality rating in Table 2 is a subjective rating, from (poor) 

 to 10 (good), determined by the field investigators after examining the data on 

 hand, field notes, and all profile plots. Using this approach, it was deter- 

 mined that data collected 18 June 197A and 27 March 1975 (see Fig. 7) were 

 unreliable (Table 2) . 



In the survey analysis, deposition from upcoast (northerly) transport 

 during times of reversals in wave direction and possible deposition due to 

 reversals in the area of the trap seaward and upcoast of the jetties were 

 examined. Figure 9 is a plot of the first profile upcoast of the jetties. 

 Survey dates of 17 April 1974 and 16 September 1975 are plotted, showing the 

 total change at this profile over that period. The plot shows little deposi- 

 tion at the end of the jetty. All profile data were examined in detail to 

 define the area of deposition attributable to influx of material from north 

 (upcoast) to the trap. No significant deposition was measured at distances 

 more than 485 meters from the base line. Using this distance (485 meters) from 

 the base line as an outward boundary to calculate volumes, errors due to influx 

 of material from reversals were minimal. 



Volume changes were calculated, using the area between the base line and 

 485 meters offshore and the north jetty and 670 meters upcoast. Over this area 

 a volume accuracy of within ±5,000 cubic meters was expected when survey errors 

 had been minimized. 



.16 Sept. 1975 



50 100 150 200 250 300 350 400 450 500 550 600 



Distance from Bose Line (m) 



Figure 9. Range 101+00 at beginning and end of study. 



22 



