Beach Erosion

1. Beach Erosion

2. Part 1 Natural Beach Erosion

3. Blowing wind puts energy into waves

4. 1. How does energy get into most ocean waves? • Sunlight • Density differences • Wind • Hydrothermal vents

5. 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!

6. 2. What causes longshore current? • Objects falling from space • Waves hitting the shore at an angle • Undersea earthquakes • Sunlight

9. 3. What are barrier islands made up of? • Coral • Volcanic rock • Sand • Sedimentary rock

10. 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.

11. 4. How can a swimmer escape a rip current? • Swim parallel to the shore • Swim out to sea with the current • Swim against the current towards shore • Let the current carry you until you get to shore

13. Rip currents form as water flows out between sand bars. Notice the dark areas in the photos

14. 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.

15. 5. Ocean City, Maryland is a barrier island • True • False

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

17. Natural barrier island migration

18. 7. It is natural for barrier islands to move. • True • False

19. Part 2 Human influences

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

21. 8. How does a jetty slow beach erosion? • Jetties stop waves from hitting the beach • Jetties add sand from the sea floor to the beach • Jetties stop sand from leaving the beach • Jetties block the waves from hitting the shore

23. These jetties, also called groins, block the sand from moving down the beach. Note the direction of drift.

24. What is the direction of longshore drift here? A B C D

25. A B This is a jetty in Ocean City, New Jersey. D 9. Which arrow shows the directionof longshore drift? C

26. 10. How many jetties do you count on this stretch of beach? • 1 • 25 • 5-10 • none

27. Jetties/Groins side view Based on the images you’ve seen, use your imagination to draw the side view on your paper.

29. This view of Baltimore’s Inner Harbor shows the top of the seawall. What would happen to Baltimore’s streets and buildings if the seawall were not there?

30. If you’ve shopped at the Inner Harbor, you’ve been to these places! seawall

31. Sea Wall side view Based on the images you’ve seen, use your imagination to draw the side view on your paper.

32. 11. What are the walls facing the sea called? • Jetties • Seawalls

33. Dunes

34. Dunes Side View Sand Dunes

35. Sand dunes and fences

36. 12. What holds the sand in place at dunes? • Fences • Foot traffic • Jetties • Plant roots

37. Dredging and pumping

38. 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.

39. Dredging/Pumping top view Based on the images you’ve seen, use your imagination to draw the top view on your paper.

40. 13. Which method shoots sand from the sea floor onto the beach? • Jetties • Sand Dunes • Sea Walls • Dredging and Pumping