1. COASTS

2. Theme Overview
COASTS
PROCESSES
COASTAL
LANDFORMS
MANAGEMENT

3. Objectives define terms associated with coasts
describe the relationship between wave energy and fetch
explain how swash and backwash is formed.
describe the characteristics of constructive and destructive waves.

4. Define: Coast
It refers to a zone where land meets and interacts with the sea.

5. AGENT 1 WAVES

6. Define: Waves
Waves: refers to a rising and falling movement of the water surface.
It is produced by winds blowing across the ocean or sea.

7. R/Ship: Erosion & Waves
The extent of erosion depends on the energy of the waves.
Factors affecting wave energy
Wind Energy
Fetch

8. Factor: Wave Energy Wind Energy
The greater the difference in pressure, greater the wind speed.
The greater the wind speed, larger the waves and greater the extent of erosion.

9. Factor: Wave Energy Fetch
This refers to distance over which wind blow across open water to form waves.
The longer the fetch, the larger the waves and greater the extent of erosion.

10. Types of Waves
Swash
Backwash

11. Waves approach the coast
Shallow sea bed causes friction
Friction causes loss of energy
Waves (back) pushes waves (front)
Waves (front) forced to rise
Waves collapse and breaks
SWASH!!!

12. DEFINITION: SWASH
This refers to the forward movement of a wave onto the beach.
Swash brings materials to the beach. Hence it is also known as constructive waves.

13. Swash moves up the coast
Wave energy is gradually lost
Gravity pulls the wave back
Waves move back into the sea
BACKWASH!!!

14. DEFINITION: BACKWASH
This refers to the backward movement of waves into the sea.
This causes the removal of materials from the beach. Hence it is also known as destructive waves.

15. Constructive Vs Destructive Waves

16. DESTRUCTIVE WAVES Large, high waves Common on steep coastal slope
Plunging over when breaking
More powerful backswash than swash
Erodes coasts

17. CONSTRUCTIVE WAVES Small, low waves Common on gentle coastal slope
Spilling over when breaking
Builds coast up by deposition