presenting the data involves fixing the longshore distance by selecting 
data from a given range and analyzing the surveys along that range. The 
surveyed distance-elevation pairs along that range are used to obtain the 
interpolated position of equally spaced depths; e.g., -0.1, -0.2, and 
-0.3 on the hypothetical profile in Figure 9(a). These contour positions 
from each survey are then plotted against time (Fig. 9,b). 
A horizontal line in Figure 9(b) represents no change in contour 
position. An upward-sloping line indicates landward movement of contour 
position (i.e., erosion); a downward-sloping line indicates deposition. 
The slope of a line indicates the rate of erosion or deposition (horizon- 
tally) at that elevation. The three x's at time t, (Fig. 9,b) indicate 
multiple contour positions at elevation -0.2 which is shown by the 
intersection of the dashline with profile t, in Figure 9(a). 
Three types of contour movement plots included in this study are: 
(a) The seawardmost intercepts along one range for specified depths; 
(b) the seawardmost intercepts for one selected depth along all ranges; 
and (c) all contour intercepts including multiple intercepts along one 
range, for up to 12 selected depths. The coordinate system used for the 
contour movement plots is shown in Figure 10. 
The elevations referred to in the discussion that follows are: 
-0.1 foot (-3.0 centimeters), -0.2 foot (6.1 centimeters), -0.8 foot 
(24.4 centimeters), -0.9 foot (-27.4 centimeters), -1.0 foot (-30.5 
centimeters), -l1.1 feet (-33.5 centimeters), -1.2 feet (-36.6 centi- 
meters), -1.3 feet (-39.6 centimeters), -1.5 feet (-45.7 centimeters), 
-1.6 feet (-48.8 centimeters), -1.7 feet (-51.8 centimeters), -1.8 feet 
(-54.9 centimeters), -1.9 feet (57.9 centimeters), -2.0 feet (61.0 
centimeters), -2.1 feet (64.0 centimeters), and -2.2 feet (-67.1 centi- 
meters). 
b. Profile Zones. Definitions of coastal engineering terms used 
in LEBS reports conform to Allen (1972) and the Shore Protection Manual 
(SPM), (U.S. Army, Corps of Engineers, Coastal Engineering Research 
Center, 1977). In this study, the wave broke at the toe of the fore- 
shore and, thus, there was no inshore zone. The boundary between the 
foreshore and offshore zones is defined for these profiles at elevation 
-0.9 foot, which was the bottom of the foreshore and the lower limit 
of the backwash effect but not the lower limit of backwash. 
A definition sketch of the profile zones shows the major changes 
along the center range of experiment 72A-06 (Fig. 11). Profiles up to 
100 hours (solid line in Fig. 1l,a) had a long, steep foreshore and an 
offshore zone consisting of an almost flat shelf between stations 8 and 
18, a steep slope near station 18, and a flat area between stations 22 
and 30. Later profiles in experiment 72A-06 (broken line in Fig. 1l,a) 
also had a long, steep foreshore but a more gently sloping offshore. 
The boundary between the foreshore and offshore remained stationary. 
Profiles in experiment 72A-10 (Fig. 11,b) had a steep foreshore and an 
offshore that consisted of an almost flat shelf between stations 5 and 
12 and a flatter seaward slope, but no offshore flat area. 
20 
