Table 5 (Concluded) 



Target 



Easting 



Northing 



Elevation, m (ft) 



South Jetty (continued) 



56 



2177231.46 



462314.69 



6.09(19.99) 



57 



2177227.63 



462323.25 



5.43(17.82) 



58 



2177222.17 



462326.94 



4.20(13.77) 



59 



2177218.84 



462326.78 



5.04(16.54) 



60 



2177212.47 



462326.46 



5.21 (17.09) 



(Sheet 4 of 4) 



moved upward slightly and some slightly subsided. The majority of elevation 

 changes was less than 0.03 m (0.1 ft) on both structures. 



Comparisons of armor unit movement data to this point have included only 

 target data and not movement of the entire armor unit. Therefore, to assess the 

 motions of the entire armor unit, outlines of each targeted dolos were extracted 

 from the stereo models and compared for the 1994 and 1998 surveys. These 

 comparisons depicted horizontal positions, and actual distances moved were 

 scaled off the photogrammetric maps that were prepared. To determine vertical 

 movements of the targeted armor units, additional elevations were obtained from 

 the stereo models at one or two additional points on the dolosse (points other 

 than the established targets). An example of the position of a targeted armor unit 

 and additional elevations for the two surveys is shown in Figure 28. 



Evaluation of horizontal motions of the targeted dolosse indicated that, for 

 the majority of units, movement was relatively uniform. The entire unit tended 

 to move in the same direction (linear as opposed to rotational). Forty-eight per- 

 cent of the targeted armor units on the north jetty and 20 percent of those on the 

 south jetty slightly rotated in either a clockwise or counterclockwise direction. 

 Considering all the rotated armor units on both structures, there was not a domi- 

 nance of clockwise or counterclockwise rotation observed. However, the majo- 

 rity of the armor units that rotated on the north jetty tended to move in a 

 clockwise direction, while those on the south jetty tended to rotate in counter- 

 clockwise directions. In general, randomly placed dolosse tend to be oriented 

 with one fluke positioned near vertical and the other lying near horizontal. In 

 some cases, the vertical fluke is positioned nearer to the jetty center line and the 

 horizontal portion downslope farther from the jetty center line. In other 

 instances, the horizontal fluke is placed closer to the center line with the vertical 

 fluke farther downslope. Of the targeted armor units that rotated on the jetties, 

 the majority consisted of those placed with the vertical fluke farther downslope 

 and the horizontal fluke closer to the jetty center line. Considering movements 

 of the entire armor unit, maximum horizontal displacements for any point on the 

 targeted dolosse on the north and south jetties were approximately 0.7 m (2.3 ft) 

 and 0.091 m (0.3 ft), respectively, between 1994 and 1998. The averages of the 

 maximum horizontal movements for the targeted dolosse during this time frame 



Chapter 3 Current Monitoring Plan and Data Comparison 



43 



