Page 422 - Laboratory Manual in Physical Geology

ACTIVIT Y 15.4 The Threat of Rising Seas

Name: ______________________________________ Course/Section: ______________________ Date: ___________

In planning for coastal management and safe and economical coastal development, responsible planning commissions and real
estate developers should “play it safe” and assume that sea level will continue to rise. There are many predictions of future rises in
global mean sea level, but regional trends should also be considered as in these examples.

A. Imagine that you are planning to buy a shorefront property in Ocean City, Maryland, this year. You plan to use the property
for family vacation getaways over the next 50 years and then sell the property. The front door of the property was four feet
above mean sea level in 2010.

1. According to the U.S. National Oceanic and Atmospheric Administration, the historic rate of sea level rise here since 1975
has been 5.48 +/– 1.67 mm/yr. Using the “plus or minus” error, what has been the minimum rate and the maximum rate
of mean sea level rise here in mm/yr?

a. __________________ mm/yr minimum rate b. ____________________ mm/yr maximum rate

2. Using the minimum and maximum rates above, calculate how much sea level will rise in mm and inches at Ocean City
over the next 50 years.

a. __________________ mm minimum b. ____________________ inches minimum

c. __________________ mm maximum d. ____________________ inches maximum

3. Mean sea level is the average position of sea level between low and high tides. High tides occasionally reach 2.9 feet
(0.88 m) above mean sea level here, and storm surges often raise sea level an additional foot (0.3 m). When Hurricane
Sandy passed offshore of Ocean City in 2012, the storm surge caused a total storm tide of 3.59 feet. Given these natural
day-to-day variations in sea level, and the prospect of sea level rise calculated above, would it be a wise decision to
purchase the shorefront property that you planned to buy? Explain your reasoning.

4. The City of Ocean City expects the following temporary increases in sea level due to storm surges in hurricanes. How
would this affect your purchasing decision? Why?
Category 1 hurricane: 74–95 mph winds, Storm Surge: 4–5 feet
Category 2 hurricane: 96–110 mph winds, Storm Surge: 6–8 feet
Category 3 hurricane: 111–130 mph winds, Storm Surge: 9–12 feet
Category 4 hurricane: 131–155 mph winds, Storm Surge: 13–18 feet
Category 5 hurricane: 156 mph + winds, Storm Surge: more than 18 feet

5. REFLECT & DISCUSS Given the fact that most existing topographic maps of coastal areas have contour intervals of
5 feet, what would you suggest as the contour line below which construction of the living/working floor of homes should
not occur along the Ocean City coast? Explain.

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