V SHORELINE POSITION 

 VERTICAL OflTUn 18 ML 

 HQRIZONTRL DATUIt 18 

 BASE LINE 



-190 -100 -SO SO too 180 ZOO 



OISTHUCe ( H) 



Figure 13. Surveys of profile line 4 at plot 2 (sand fence with side spurs) 



segments of the plot had trapped similar amounts of sand, 30 and 35 cubic 

 meters. Final crest elevation in the southern section was somewhat lower than 

 the northern section, 4.9 versus 5.3 meters. Dune slope of the southern sec- 

 tion was 1 on 15 landward and 1 on 18 seaward. Dune slope in the undamaged 

 section was twice as steep, 1 on 7.7 landward and 1 on 7.9 seaward. Base 

 width of the dune in 1977 was about 41.2 meters in the southern section and 

 about 32.9 meters in the northern section. While the bayward shore remained 

 stable, the seaward shore retreated about 25 meters during the 8 years of 

 observation. 



d. Performance Summary. Table 4 summarizes dune development from 1970 to 



1977. 



3. American Beachgrass with 60-Centimeter Spacing (Plot 3) . 



a. Installation, Damage, and Repair. Plot 3 was planted in 1970 with 



American beachgrass on 60-centimeter centers, three to five sprigs per hill. 

 Survival was initially very low (about 10 percent as measured in June 1971) 

 because of the migration of a storm berm into the planting area. The plot was 

 replanted in October 1971. Much of the replanted area was buried with sand 

 during a February 1972 storm and survival of the second planting was less than 

 20 percent the following year. Observations in May 1973 indicated that the 

 area was replanted, possibly by local volunteer groups, though no additional 

 planting was made as part of this study (Fig. 14). The presence of the storm 

 berm in the planting area and evidence of overwash were observed in October 

 1973 and May 1974. After 1973, two washover areas became natural pathways for 

 foot and vehicular traffic. These two thoroughfares, lying east-west, con- 

 nected the seaward beach with a pathway running north-south that roughly 

 bisected the dune longitudinally. Neither of the plot 3 profile lines (lines 

 5 and 6) coincide with the east-west thoroughfare; however, the north-south 



2i 



