1. Coastal Processes

2. Objectives Examine Physical Properties of Waves
Examine behavioral changes of waves approaching coast
Explain the role of waves in sediment erosion, transportation and deposition
Discuss tides and their role in coastal erosion and deposition
Discuss effects of storms and crustal movement on coastal landscapes.

3. Coastal Processes Shape the landscapes along the coast Impact humans
Must understand processes shaping coast
Impact humans
More and more people moving to coast
Coastal areas heavily developed
Must learn to manage coastal areas
Knowledge of coastal processes is management key

4. Waves Most important agent in shaping coastal landforms
Size of waves depends on:
Velocity
Wind persistance
Fetch
Garrison, Oceanography An invitation to marine science

5. Wave Properties Height = vertical distance from crest to trough
Wavelength = horizontal distance between successive crests or troughs
Wave period = time required for two successive crests to pass a fixed point

6. Motion in Deep Water Waves
Motion is orbital
Waves with orbital particle motion termed waves of oscillation
Particle motion ceases at ½ wavelength

7. Waves Against the Shore
Swells shoal as approach coastline
Feel bottom at ½ wavelength
Wavelength decreases
Wave height increases
Wave particle motion becomes elliptical
Wave breaks
Swash and backwash move on beach

8. Wave Refraction Bending of waves as they approach coastline
Part of wave in shallow area slows
Part of wave in deeper area continues with higher speed
Results in longshore current

9. Erosion of Coastal Headlands
Wave refraction concentrates energy on headlands
Sand accumulation occurs in lower energy bays
Results in straightening of coastline

10. Shore Zone Currents—Rip Currents
Strong narrow currents moving from beach to ocean
May be identifiable through interruption of breakers and muddier sediment moving seaward

11. Shore Zone Currents—Longshore Currents
Currents moving along the coast set up by wave refraction

12. Longshore Drift
The movement of sediment along the shoreline by longshore currents
Beach drift is movement of sediment on the beach
Swash moves sand at an angle up beach
Backwash swash moves sand down the beach
Groins and other structures used to interrupt drift and stabilize beaches

13. Tides High and low tides tend to widen beaches
Tidal range is greatest in estuaries, bays, and lagoons
Erode and deposit sediment
Erosion occurs in narrow rocky bays with great tidal ranges
Where currents slow down deposition takes place

14. Tides

15. Storms May modify coastal areas in short period
Storm surges plus low atmospheric pressure result in increased sea level
Wave aggressively attack coastal features
High tides aggravate conditions

16. Crustal Movements Influence development of coastal features
Tectonic activity leads mostly to raising and erosion of coast
California, Oregon, & Washington are examples
Some coastal areas are sinking due to accumulation of sediment
Texas and Louisiana are examples