sea

• Types of waves


  • Destructive
  • Constructive
• Erosion


  Rocks are broken down and carried away by something (e.g. sea water)
• Destructive waves


  Erode the coast and destroy the beach
• Constructive waves


  Deposit material at the coast and build up the beach
• Destructive waves


  Backwash is more powerful than swash
• Longshore drift


  The way water moves in a specific direction, following the direction of the prevailing wind, with the swash carrying material up the beach and the backwash carrying it down the beach at right angles, resulting in a zigzag pattern along the coast
• Constructive waves


  Swash is more powerful than backwash
• Longshore drift


  1. Waves follow the direction of the prevailing wind

  2. Waves hit the coast at an angle

  3. Swash carries material up the beach

  4. Backwash carries material down the beach at right angles

  5. Material zigzags along the coast
• Processes of transportation


  • Traction (large particles like boulders pushed along the seabed)
  • Saltation (pebble-sized particles bouncing along the seabed)
  • Suspension (smaller particles like silt and clay carried in the water)
  • Solution (soluble materials dissolved in the water)
• Deposition


  Occurs when water carrying sediment loses energy and slows down, letting go of the material
• Factors affecting the rate of deposition

  • Rate of erosion elsewhere (material availability)
  • Amount of material already transported into the area
• Hard engineering


  Man-made structures built to control the flow of the sea and reduce flooding and erosion
• Soft engineering


  Schemes that are set up using knowledge of the sea and its processes to reduce the effects of flooding and erosion
• Seawall


  • Wall built at the edge of the coastline to protect the base of cliffs, land and buildings against erosion
  • Can also prevent coastal flooding
  • Expensive to build
  • Curved seawalls reflect wave energy back onto the sea, keeping waves powerful
  • High maintenance costs over time
• Groins


  • Wooden barriers built at right angles to the beach
  • Prevent the movement of beach material along the coast (longshore drift)
  • Allow the build-up of a beach
  • Beaches are a natural defense against erosion
  • Attractive for tourists
  • Can be seen as unattractive
  • Costly to build and maintain
• Rock armor and boulder barriers

  • Large boulders piled up on the beach
  • Absorb wave energy
  • Allow the build-up of a beach
  • Expensive to obtain and transport
• Beach nourishment


  • Replaces beach or cliff material removed by erosion or longshore drift
  • Beaches are a natural defense against erosion and coastal flooding
  • Attractive for tourists
  • Relatively inexpensive but requires constant maintenance
• Managed retreat


  • Areas of the coast are allowed to erode and flood naturally, usually low-value areas
  • Encourages the development of beaches and natural defenses like salt marshes
  • Low cost but requires compensating people for loss of buildings and farmland
• Hard engineering strategies include seawalls, groins, and rock armor/boulder barriers
• Soft engineering strategies include beach nourishment and managed retreat