Beach Erosion

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Beach Erosion
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Part 1

• Natural Beach Erosion

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• Blowing wind puts energy into waves

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1. How does energy get into most ocean waves?

1. Sunlight
2. Density differences
3. Wind
4. Hydrothermal vents

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When the waves hit the shore, they travel at an
angle.

• The water hitting the beach can pick up and move
  grains of sand.

Top View
People, too!
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2. What causes longshore current?

• Objects falling from space
• Waves hitting the shore at an angle
• Undersea earthquakes
• Sunlight

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3. What are barrier islands made up of?

1. Coral
2. Volcanic rock
3. Sand
4. Sedimentary rock

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Rip currents, sometimes called rip tides, are
dangerous. They pull swimmers under water and
away from shore. If caught in a rip current, you
may escape by swimming parallel to the shore and
out of the current.
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4. How can a swimmer escape a rip current?

1. Swim parallel to the shore
2. Swim out to sea with the current
3. Swim against the current towards shore
4. Let the current carry you until you get to shore

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Rip currents form as water flows out between sand
bars. Notice the dark areas in the photos
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Ocean City, Maryland is a barrier island. In
1933, a storm washed away this part of the
island, opening a connection between the
bayside and oceanside parts of Ocean City.
Before that event 2 parts of the island were
connected.
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5. Ocean City, Maryland is a barrier island

1. True
2. False

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6. Ocean City, Maryland used to be 1 long island
until a storm broke it into two islands

1. True
2. False

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Natural barrier island migration
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7. It is natural for barrier islands to move.

1. True
2. False

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Part 2

• Human influences

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Jetties

• A jetty is a wall built out into the ocean.
  Jetties slow beach erosion by stopping sand from
  being carried away.

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8. How does a jetty slow beach erosion?

1. Jetties stop waves from hitting the beach
2. Jetties add sand from the sea floor to the beach
3. Jetties stop sand from leaving the beach
4. Jetties block the waves from hitting the shore

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These jetties, also called groins, block the sand
from moving down the beach.
Note the direction of drift.
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What is the direction of longshore drift here?
A
B
C
D
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A
B
This is a jetty in Ocean City, New Jersey.
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9. Which arrow shows the directionof longshore
drift?
C
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• 10. How many jetties do you count on this stretch
  of beach?
• 1
• 25
• 5-10
• none

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Jetties/Groins side view

• Based on the images youve seen, use your
  imagination to draw the side view on your paper.

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This view of Baltimores Inner Harbor shows the
top of the seawall.
What would happen to Baltimores streets and
buildings if the seawall were not there?
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If youve shopped at the Inner Harbor, youve
been to these places!
seawall
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Sea Wall side view

• Based on the images youve seen, use your
  imagination to draw the side view on your paper.

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11. What are the walls facing the sea called?

1. Jetties
2. Seawalls

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Dunes
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Dunes Side View
Sand Dunes
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Sand dunes and fences
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12. What holds the sand in place at dunes?

1. Fences
2. Foot traffic
3. Jetties
4. Plant roots

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Dredging and pumping
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This is a dredging ship
This picture is of the land-side of the submerged
pipe just as the first load of sand is being
pumped through it.
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Dredging/Pumping top view

• Based on the images youve seen, use your
  imagination to draw the top view on your paper.

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13. Which method shoots sand from the sea floor
onto the beach?

1. Jetties
2. Sand Dunes
3. Sea Walls
4. Dredging and Pumping