sediment transport rates or "littoral drift" mainly from areal changes between 
shoreline surveys. Four shoreline reaches in the project area were examined 
by this method. The bifurcation or nodal point in the longshore transport 
rate was located at Dover Township, between Manasquan Inlet to the north and 
Barnegat Inlet to the south. North of Dover Township the net transport rate 
was found to be directed to the north, increasing from 0 at the section Man- 
tolokung to Manasquan, to 74,000 cu yd/year between Manasquan and Asbury 
Park, 319,000 cu yd/year from Asbury Park to the base of Sandy Hook, and 
493,000 cu yd/year along Sandy Hook (Figure 6). The transport rate along 
Sandy Hook during the approximate 50-year interval 1899-1953 was 12 percent 
lower than that for the previous approximate 60-year interval (1838-1899). 
This decrease was attributed to active groin and jetty construction. However, 
this conclusion cannot be applied to long-term changes since the beach in a 
groin field may eventually reach a filled state and thereafter bypass sand. 
Also, errors in measurement and interpretation of shoreline position and beach 
profiles are probably larger than 10 percent, making firm conclusions about a 
12 percent change in transport rate doubtful. Additional seawall construction 
in the compared time interval may have reduced the transport rate by elim- 
inating sources of sand that might otherwise be transported north. 
29. In order to compute volumetric beach change based on shoreline 
data, not only change in shoreline position but also associated profiles for 
the compared dates must be available. Caldwell did not specifically address 
this critical third dimension in his paper. For the 1885 and 1933 surveys, 
profiles were compared to "about the 30-foot mean low water contour" (CE 1954, 
p 44). The budget analysis technique requires the compared profiles to match 
at a pinch-off depth or depth of closure. Even with modern ocean survey tech- 
niques, pinch-off depth is a difficult quantity to determine, and inspection 
of profiles shown in Appendix D reveals some lack in achievement of pinch-off. 
The shape of the active profile also changes according to.season, with large 
volumes of sediment translating on-offshore. Volume differences between 
complex and varied profiles are difficult to calculate by hand. Therefore, 
some subjectivity entered Caldwell's analysis, but has gone undocumented. 
However, because of the long time periods involved, over which considerable 
shoreline change occurred, the order of magnitude of Caldwell's results (also 
CE 1954) is probably reliable. 
30. In this paragraph, a short summary is given of the shoreline change 
20 
