Coastal Landscapes and Waves

Introduction

• Focus on coasts, coastal landscapes, and coastal management
• Today's topic: Importance of waves in coastline environments

Definition of a Coastline

• Where land meets the sea
• Waves influence the shape of coastlines
• Human attempts to manage coastal changes

Formation of Waves

• Wind blows across the sea surface creating friction
• Friction causes small ripples forming waves
• Wave energy depends on "fetch" (strength and duration of wind)

Wave Behavior

• Deep ocean: Waves travel in circular orbit
• Approaching coastline: Friction causes elliptical shape; wave breaks
• Swash: Water rushes up the beach
• Backwash: Water retreats to the sea

Types of Waves

Constructive Waves

• Function: Construct beaches
• Characteristics:
  • Low wave height (<1m)
  • Strong swash; weak backwash
  • Long wavelength
  • Low frequency (8-10 waves/minute)
• Effects:
  • Deposits sediment, building up beaches

Destructive Waves

• Function: Erode beaches
• Characteristics:
  • Tall wave height (>1m)
  • Weak swash; strong backwash
  • Short wavelength
  • High frequency (10-14 waves/minute)
• Effects:
  • Causes erosion, reducing beach sediment

Summary of Wave Comparison

• Wave Height: Constructive (low) vs Destructive (high)
• Wavelength: Constructive (long) vs Destructive (short)
• Wave Frequency: Constructive (8-10/min) vs Destructive (10-14/min)
• Swash Strength: Constructive (strong) vs Destructive (weak)
• Backwash Strength: Constructive (weak) vs Destructive (strong)
• Net Beach Sediment: Constructive (increase) vs Destructive (decrease)

Conclusion

• Waves play a crucial role in shaping coastlines
• Different types of waves have distinct impacts on coastal environments

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