1. WAVES . . .
The motion of the ocean . . .

2. Basic Wave Structure: Wavelength Crest Trough Height Water Depth
Still Water Line
Trough
Water Depth
Height
Ocean Bottom

3. Deep Water Wave: Water depth is greater than ½ the wavelength
Particle motion in orbital pattern

4. Shallow Water Wave: Wavelength greater than water depth
Particle motion in flat elliptical pattern

5. Transitional Wave:
Wavelength greater than 2X but less than 20X the water depth
Particle motion in flat elliptical pattern

6. Water Particle Motion Wavelength decreases as depth decreases
Deep Water Wave
Shallow Water Wave
Wavelength decreases as depth decreases

7. Progressive Waves: Appear to be moving in a definite direction
Wind generated, Catastrophic, Internal
(example: rock dropped into pond)

8. Standing Waves:
Appear as vertical undulation of sea, does not propagate (move)
(example: sailboat in harbor moving up and down but no apparent waves “passing by”)

9. Wave Interference:
Constructive
Destructive
Mixed

10. Constructive Interference:
Two waves meet crest to crest and trough to trough
Resulting new wave has same original wavelength and height is the total sum of two original waves

11. Destructive Interference:
Two waves meet crest to trough and trough to crest
Resulting new wave is canceled out leaving calm surface

12. Mixed Interference: Two waves of different heights and lengths meet
Resulting new wave has irregular wave pattern created, sequence of high waves followed by sequence of low waves

13. Fetch – the distance over which the wind blows in one direction
Wave Action:
Refraction
Reflection
Diffraction
Fetch – the distance over which the wind blows in one direction

14. Refraction:
Process by which the part of wave in shallow water is slowed down to cause wave to bend and tend to align itself with underwater contours

15. Reflection:
Process by which a wave has part of its energy returned seaward by a reflecting surface (shoreline)

16. Diffraction:
Any bending of a wave around an obstacle that can not be interpreted as refraction or reflection

17. Wave Breaking:
Ideally, when water depth is 1.3 times breaker height, the crest will topple
Spilling breaker
Plunging breakers
Surging breakers
Deep water waves hit bottom in shallow water (reef, etc), look like walls of white water (tsunami)

18. Erosion . . . Effects of waves . . .
Summer – low energy waves cause beaches to build out
Winter – high energy waves cause the sand to be removed

19. Erosion . . .
Steep, narrow, rocky headlands or coast caused by HIGH ENERGY waves
Broad gentle slopes with sandy beaches, calm coast or bay caused by LOW ENERGY waves

20. Erosion

21. Wave Effect: Headlands vs Bays
Energy is spread out = smaller waves
Bay Shore
Headland Shore
Energy is concentrated = large waves

22. Bay & Headland

23. Protection Against Erosion:
Natural protection (dunes, plants)
Man made objects - built to protect the shore and may work for a limited area, but often increases erosion to adjacent land (sea wall, breakwater, jetty/groin)

24. Area of increased erosion
Sea Wall (revetment). . .
Area of increased erosion

25. Sea Wall (Revetment)

26. Area of increased erosion
Breakwater Wall . . .
Area of increased erosion
Longshore current
Calm area (sand deposited)

27. Breakwater Wall
Harbour

28. Rock Groin (short) or Jetties (long) . . .
erosion
erosion
deposition
deposition
Longshore current
Longshore current

29. Jetty/Groin

30. Natural - Vegetation

31. Natural - Dune