Enquiry Question 2 Flashcards
How are waves created?
Friction between the wind and surface of the water generates circular movements of energy
What happens when the wave approaches the shore?
The bottom of the wave experiences friction with the sea bed, causing the bottom of the wave to slow down faster than the wave crest. Therefore the movement becomes eliptical. This causes the wave to break, creating breakers.
What impacts the strength of a wave?
- Wind speed/ strength
- The fetch
- The duration of the wind
Fetch
Distance the wave travels in open water
Swell waves
Waves continue after wind stops, they have a long time to lose energy.
Characteristics of constructive waves
- Have a long wavelength
- Low frequency of waves: Every 6-8 mins
- The swash is stronger than the backwash (surging waves)
- Very little erosion caused by backwash
- Causes a gradual build-up of sediment creating a flatter beach
- Very low wave height
Surging waves
The swash is stronger than the backwash
Characteristics of destructive waves
- Shorter wavelength
- More frequent waves: 10-15 mins
- Backwash stronger than swash
- Very little deposition; more erosion
- Much steeper beach profile
- Sand removed from the beach is deposited offshore creating an offshore bar
- High wave height
- High energy environment
Sediment profile:
The pattern of distribution of different sized or shaped deposited material
Formation of an Offshore bar:
Destructive waves, backwash removes sediment off the beach.
As the backwash loses energy, deposition occurs in the offshore/nearshore region
Once the ridge exists, it creates more friction with backwash, leading to more deposition and therefore larger offshore bars.
Swash aligned beach
When beaches/ coastlines are sheltered means waves run parallel to the beach and are swash aligned
Ridges
Areas of the foreshore that are raised
Runnels
A shallow trough in the foreshore
Berms
Shingle ridges formed beneath the storm beach
Storm Beach
Very coarse sediment deposited here during severe storms
