Lecture 16: Coastlines and Real Estate
Focus Question: How does coastal change impact real estate?
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Coastlines and Beaches: The problem of Erosion
1. “Approximately 25 percent of homes and other structures within 500
feet
of the
of erosion within the next 60 years, according to a study released recently by
the
Federal Emergency Management Agency (FEMA, 2000)”.
2. “Sixty percent of nationwide losses will occur along the Atlantic
and Gulf of Mexico
coastlines (FEMA, 2000), with costs to
billion dollars per year (FEMA, 2000)”.
3. Coastal Erosion is driven by storm activity (especially hurricanes)
and by longshore
current activity. Property owners try to slow or stop erosion, but this
usually doesn’t work.
Examples:
Longshore transport,
4. Shaping a
Longshore drift = movement of sand along a beach by
wave action
Graphic: Garrison Fig. 12.16, pg. 326 (Fig. 12.15, pg 285).
5. Shoreline Stabilization
People have attempted to stabilize coasts and beaches using:
Groins - walls perpendicular to the shore
Seawalls - "armoring" the shore
Sand replenishment - importing sand
Graphic: Garrison, Figs. 12.35 and 12.36, pgs. 341-342 (Figs. 12.33 and 12.34, pg 299.)
6. Other Shore Stabilization Strategies
Riprap - irregular rocky structures that dissipate wave energy
Wind Fences - reduce beach erosion by the wind
7. Along-Shore Drift - An Example
Sand accumulates "upstream" of the barrier
Sand is depleted and erosion is accelerated "downstream" of the
barrier
8. Coastal Erosion
Coastal erosion varies from place to place, depending on
- hardness and resistance of rock
- wave action
- local range of tides
Graphic: Garrison, Fig. 12.38, pg. 343, (Fig. 12.36, pg 300).
9. FEMA Federal
Emergency Management Agency,
independent federal agency, reports directly to the President since 1979
has 27 other federal partner agencies, and is also partnered with the American
Red Cross
10. FEMA includes the Federal Insurance
Administration,
the National Fire Prevention and Control Administration,
the National Weather Service Community Preparedness Program,
the Federal Preparedness Agency of the General Services Administration
and the Federal Disaster Assistance Administration activities from HUD.
11.
subject to severe erosion during storms
in the
famous barrier islands include
Ocean City, MD
Miami Beach FL
Palm Beach, FL
12. FEMA regulations, rebuilding after storm
destruction
a. structure must be 2 feet higher than the water level that destroyed it
b. no new construction on barrier islands
13. Choosing a coastal property
a. which direction is the longshore transport?
b. Is your section of beach gaining or losing?
c. Where is the dune field?
d. What changes are being made to the beach just upcurrent
and downcurrent from you?
e. Is there a recent history of erosion/storm damage?
f. Is the house on a cliff? What is the condition of the foot of the
cliff?
g. Do you know where to get coastal erosion maps or flood maps?
Next lecture: Coastlines and Pollution Reading: Ch. 12, pgs. 336-340, Ch. 18, pgs. 505-523 (Ch. 12, 295-297,
Focus Question: What are the sources of pollution in the ocean?