shoreline is the difference hetween the prestorm and poststorm positions 
of the MSL intercept on the profiles (poststorm distance minus prestorm 
distance). In those cases where MSL intersects the profile more than once 
(usually due to an accretionary ridge on the poststorm profile), the most 
seaward of the multiple intercepts is defined as the shoreline. 
In the tables, unit volume change (in cubic yards per lineal foot of 
beach) is given in two ways: ''PRCHAR' unit volume and "Plus 12" unit 
volume (Fig. 8). For most cases, PRCHAR unit volume is identical to Plus 
12. Both unit volume changes are measured above MSL; i.e., above a hori- 
zontal line drawn landward from the most seaward MSL intercept. If either 
the prestorm or poststorm survey reaches 2 feet MSL but failed to cross 
MSL (perhaps because of high water at the time of the survey), that profile 
was extrapolated linearly to MSL. If either of the before-or-after pro- 
files did not cross 2 feet MSL, unit volume was not computed. A positive 
area change indicates a net accretion on the profile line; negative area 
change indicates net erosion. 
The distinction between PRCHAR and Plus 12 unit volume changes is in 
the limits on the landward side of the profile. The PRCHAR landward limit 
is defined by a vertical line intersecting both profiles and passing 
through the landward termination of at least one profile. (In most cases, 
both profiles terminate landward at the same point.) The Plus 12 landward 
limit is defined by drawing a horizontal line at +12 feet MSL elevation 
through both profiles, provided both profiles go above +12 feet MSL. If 
there is more than one Plus 12 intercept on a profile, the most seaward 
Imtercept.1sS used) lf eather oryboth profilies; fail to exceed +12 feet 
elevation, then the landward limit is the PRCHAR limit, modified if nec- 
essary so as not to include area above +12 feet elevation. 
The choice of which landward limit to use becomes important on high 
profiles such as those at Cape Cod, Westhampton Beach, and Long Beach 
Island. The Plus 12 unit volume change differs from PRCHAR in not includ- 
ing the effect of changes at high elevations on cliffs, bluffs, or high 
dunes. Such changes include accretion of windblown sand and slumping of 
unstable slopes. 
1. Cape Cod, Massachusetts. 
The profile line locations are plotted in Figure 9, surveyed storm 
changes in Figure 10, and MSL contour and area changes in Table 3. A 
trend of decreasing erosion from north to south was noted which corre- 
lates with changes in beach morphology from the high (greater than 100 
feet on profile 02), actively eroding scarps at Wellfleet, to the low 
accreting spit of Nauset Beach. Generally, erosion seemed to be greatest 
on the upper part of the profile (above +2 feet MSL) with deposition 
occurring below +l foot elevation. The average net unit volume change 
above MSL between 10 and 18 December on the 10 Cape Cod profile lines was 
-5.5 cubic yards per foot or -8.1 cubic yards per foot if profile line 06 
is eliminated because of the suspiciously large accretion on the face of 
hey eilantre 
23 
