Constructive and destructive waves

1. Lesson ObjectivesLesson Objectives
This lesson is looking at the different types of wave
you can get and how they effect the coast
differently.
By the end of the lesson you should be able to:
Name the two types of wave
Describe the differences between them
Explain how they change the coastline in different
ways.

2. What is the definition of a
coastline?

3. The coast – a narrow zone where
land, sea and atmosphere meet

4. Swash and Backwash!
Swash
Backwash

5. Constructive Waves
Swash
Backwash
Material deposited on beach

6. Destructive Waves
Swash
Backwash
Material eroded off beach

7. Destructive waves mean steep, stepped beach caused by waves pulling sediment
off the beach
Constructive waves mean wide, flat and usually sandy beaches as waves deposit
sediment on the beach

8. Constructive Waves
Destructive Waves

9. Constructive and Destructive WavesConstructive and Destructive Waves
ConstructiveConstructive
•Height = Low (less than 1
metre)
•Length = Long
•Frequency = Fewer than 10 a
minute
•Energy = Low
•Beach gradient = flat
•Main process = deposition
•Stronger swash
DestructiveDestructive
•Height = High (more than 1
metre)
•Length = Short
•Frequency = More than 10 a
minute
•Energy = High
•Beach gradient = steep
•Main process = erosion
•Stronger backwash

10. Key WordsKey Words
Fetch – the distance a wave has travelled
Swash – the forward movement of a wave up the beach
after the wave has broken
Backwash – water from a breaking wave which flows under
gravity down the beach
Constructive Wave – deposits sediment, building up the
beach
Destructive Wave – a wave that removes sediment from
the beach, eroding it.