Lecture Notes: Coastal Geography

Wave Action

• Fetch: The distance over water that the wind blows uninterrupted.
• Factors Influencing Wave Size:
  • Strength of the Wind: Stronger wind creates larger waves.
  • Duration: Longer wind duration increases wave size.
  • Fetch Size: Longer fetch results in larger waves.
• Prevailing Wind: Dominant wind direction; affects wave size.
• Wave Formation:
  • Wind creates wave shapes on water.
  • Water moves in a circular motion.
  • Waves break due to friction in shallow water.
• Wave Types:
  • Constructive Waves: Long wavelength, strong swash, weak backwash; build up beaches.
  • Destructive Waves: Short wavelength, strong backwash, weak swash; erode beaches.

Coastal Weathering

• Weathering: Breakdown of rocks at the Earth's surface.
• Types:
  • Mechanical Weathering: Physical breakdown; includes freeze-thaw, onion skin weathering, wetting, and drying.
  • Chemical Weathering: Breakdown via chemicals.
  • Biological Weathering: Breakdown by living organisms.

Mass Movement

• Definition: Downward movement of sediment due to gravity.
• Types:
  • Rockfall: Rocks fall off cliffs.
  • Mudslides: Saturated soil slides down slopes.
  • Landslides: Large rock chunks slide downhill.
  • Slumping: Cliff segments move down slopes.
  • Rotational Slip: Saturated soil slumps down a curved surface.

Coastal Erosion, Transportation, and Deposition

• Erosion Types:
  • Abrasion: Rocks erode cliffs like sandpaper.
  • Hydraulic Action: Water and air in cracks erode cliffs.
  • Corrosion (Solution): Chemical erosion of cliffs.
  • Attrition: Rocks collide and become smaller.
• Deposition: Occurs when waves lose energy and drop sediment.
• Transportation: Movement of material by sea:
  • Traction: Large rocks roll on the seabed.
  • Saltation: Small stones bounce on the seabed.
  • Solution: Transport of dissolved rock.
• Longshore Drift: Sediment transport along a coast in a zigzag pattern due to angled waves.

Factors Affecting Coastal Environments

• Rock Type: Harder rocks are less prone to erosion.
• Human Activity: Settlements, tourism, and engineering strategies impact coastlines.
• Fishing Practices: Overfishing and pollution affect ecosystems.
• Climate Change: Rising sea levels due to melting ice caps.
• Vegetation: Stabilizes slopes but can lead to biological weathering.

Formation of Coastal Landforms

• Headlands and Bays: Form from differential erosion of hard and soft rocks.
• Wave Cut Platforms: Notches in cliffs created by waves; lead to cliff retreat.
• Caves, Arches, Stacks, and Stumps: Result from erosion of headlands.

Depositional Landforms

• Beaches: Formed by low-energy constructive waves.
• Spits and Bars: Created by longshore drift depositing sediment.
• Lagoons: Form behind bars.

Coral Reefs and Mangroves

• Coral Reefs:
  • Composed of coral polyps and calcium carbonate.
  • Require specific temperatures and conditions.
• Mangroves:
  • Trees that grow in coastal intertidal zones.
  • Require high rainfall and temperature, and shallow waters.

Sand Dunes and Salt Marshes

• Sand Dunes: Formed by wind-blown sand; stabilized by vegetation.
• Salt Marshes: Flooded coastal wetlands; important for biodiversity.

Coastal Ecosystem Threats

• Human Activities: Industrial waste, tourism, deforestation, agriculture.
• Pollution: Impacts biodiversity and marine life.
• Ecosystem Services: Provide food, protection, biodiversity.

Conflicts in Coastal Use

• Goods and Services: Fishing, tourism, construction.
• Conflicts: Between conservation and resource use.

Causes of Coastal Flooding

• Storm Surges: Temporary sea-level rises during storms.
• Tsunamis: Caused by underwater earthquakes.
• Climate Change: Melting ice caps lead to rising sea levels.