Coastal Hazards - Investigations in Environmental Geology - page 180

FIGURE 11.5 Aerial photograph taken in 1993 at Painesville Township Park, Lake County, Ohio (Ohio Department of Natural Resources).

22. Describe the differences between the actual recession and
the recession that you predicted. What are possible reasons
for the differences, if any?

27. Many coastal experts have suggested that structures that
interfere with longshore drift should not be build along
shorelines because they produce net erosion. Do you agree
or disagree with the experts? Explain.

23. What were the average annual recession rates at the two
lines that had the most rapid retreat between 1973 and 1993?
a. At line , the recession rate in feet/year between
1973 and 1993 was

28. As a consulting coastal geoscientist, you are asked by the
residents of the area for help in solving their problem. What
advice do you give them?

b. At line , the recession rate in feet/year between
1973 and 1993 was

PART B. ANNUAL AND LONG-TERM
WATER-LEVEL FLUCTUATIONS
ON THE GREAT LAKES

24. Compare the position and number of houses in the 1954,
1973, and 1993 photographs. What changes occurred?

Many factors control erosion rates on coasts. In addi-
tion to engineered structures, earth material, and wave
energy, among others, water level is also important.
High-water and low-water levels on the Great Lakes
cause problems for coastal communities and trans-
portation systems. The problems associated with high
water generally cause the greatest losses for individual
homeowners.
Flooding of docks, farmland, roads, and residen-
tial areas is the result of high water due to long-term
(climatic), annual (seasonal), or short-term (meteoro-
logical) conditions. Increased erosion or the potential
for it leads to lost property or expensive engineered
shore-protection systems. Even recreation is impacted

25. How do the average annual rates for recession of the
bluffs for the periods 1954-1973 and 1973-1993 compare
with the rate of recession from 1876-1937? What factors
might explain the differences?

26. If installation of the groins was a factor in the different
rates, when do you think they were installed? Explain.

Refer to Figure 11.3.