Table 1 presents shoreline positions (with and without lake level correc- 
tions) as a function of distance along the coast, as determined from the aerial 
photos. The corrected shoreline positions are referenced to a common lake level 
of 578.5 feet, as determined by a regression against lake level. Figure 23 
Shows the 1973 Holland Harbor shoreline. The origin of the coastline coordinate 
is taken at the harbor, positive in the north direction. The shoreline position 
was measured at 290-foot increments along the coast. 
A regression of shoreline position against lake level and time provided an 
estimate of the long-term evolutionary trend of the shoreline at each station 
along the coast. The regression study revealed general erosion extending south 
of the harbor and accretion immediately north of the harbor. Over an 8,410- 
foot span south of the harbor, the average beach erosion rate was 0.75 foot 
per year. Over a 4,060-foot span immediately north of the harbor, the average 
accretion rate was 1.65 feet per year. A span of 10,585 feet, starting 4,930 
feet north of the harbor, had an average erosion rate of 1.28 feet per year. 
These evolutionary trends of the shoreline include natural effects as well as 
any effects which can be attributed to the harbor. 
Figure 24 shows the evolutionary smoothed trend (defined as the average 
accretion or erosion rate between 1950 and 1973) along the coast near Holland 
Harbor. Erosion dominates south of the harbor, accretion immediately north, 
and erosion again farther north of the harbor. The smoothed curve in Figure 20 
demonstrates that the accretion resulting from the harbor extends about 5,000 
feet north of the harbor. These estimates of the evolutionary trend of the 
shoreline are subject to large annual and spatial fluctuations. 
8. Comparisons of Profiles from 1945 and 1975 Surveys. 
The surveys of May 1945 and April 1973 (lake levels at 578.4 and at 580.1 
feet, International Great Lakes Datum (IGLD), respectively) permit a comparison 
of profile changes from which sediment volume changes can be estimated. Since 
the actual profile locations in the two surveys did not coincide (in general), 
the 1945 survey was interpolated on the lines of the 1973 survey to allow a 
comparison. Table 2 summarizes the cross-sectional area changes and the volume 
computations in two parts (above and below low water datum). The last colum 
in the table gives the erosion or accretion rates determined from the aerial 
photos. 
The average volumetric accretion rate on the north side (from ground survey 
data) is 2.13 cubic yards per year per foot of shoreline for 1,950 feet (450 to 
2,400 feet north of the breakwater) compared with the average shoreline accre- 
tion rate of 1.92 feet per year for this same region determined from Figure 20. 
The average volumetric erosion rate on the south side of the harbor from the 
survey comparisons is 1.41 cubic yards per year per foot of beach, whereas the 
values from Figure 20 for the south stretch (470 to 5,550 feet south) give 0.82 
foot per year as an average rate of shoreline erosion. The agreement on the 
north side indicates that the approximation of 1 square foot of beach per cubic 
yard is reasonably valid, whereas on the south side this is less true. The dis- 
crepancy on the south side is related to the bluff erosion contribution. The 
main erosion rate below the low water datum level is only 0.16 cubic yard per 
year per foot. Hence, the bluffs contribute at least an additional 1.25 cubic 
yards per year per foot, which exceeds the conditions for the approximation of 
1 square foot of beach to correspond to 1 cubic yard of material. 
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