Beach Notes

1.Summer v. Winter Beach

• Summer:
  • Broad, gentle slope, sand on the beach
• Winter
  • Narrow, steep slope, sand moves offshore, beach may be rocky

2. East v. West

• East
  • Broad continental shelf
  • Sinking coastline
  • Broad sandy beaches, gentle slope
  • Barrier islands and offshore bars
• West
  • Narrow continental shelf
  • Rising coastline
  • Narrow, steep beaches
  • Coarse sediment, rocky

3. Littoral Cell

• Sand transport system, from sand entering system at river, along the beach, to where sand leaves system by dropping off the continental shelf.

4. Longshore current

• waves breaking at angle to beach
• water flows parallel to beach

5. Why do cliffs retreat?

• Beach is an equilibrium system
• Amount of sand carried is in equilibrium with energy of waves
• Increase wave energy, increase amount of sand that can be carried
• Decrease the amount of sand available to waves, increase the amount of erosion
• Wave energy increases in storms, so coastal erosion should increase with global warming
• Dams reduce sediment reaching to sea, so coastal erosion increases with number of dams