Waves

Key Terms:

Term	Definition
Swash	Water carried up the beach after a wave breaks
Backwash	The water that flows back down the beach to the sea
Shingle	Made up of small rounded pebbles or stones brought ashore by the sea
Marine Deposition	Another way of saying Coastal Deposition
Backshore	The area of a beach that lies above the high tide level. It is reached by waves only during stormy weather
Foreshore	The lower section of the beach next to the water
Storm Beach	Located in the backshore area and mainly consists of stones and gravel

Waves

• Coastal processes of erosion, deposition and transportation are influenced by the actions of waves
• Waves are created by friction between the wind and sea
• The size of waves depends on two things:
  • Wind Strength: the stronger the wind, the more powerful the wave
  • Fetch: The size of the ocean the wind blows over
• Large ocean combined with high winds = Stronger waves
• When waves reach shallower water at the coast, they break
• Waves running up the shore = swash
• Waves that run back towards the sea = backwash
• Top of the wave = crest
• Bottom = trough

Types of Waves

Constructive Waves

• Formed when the swash is stronger than the backwash
• As the stronger swash runs up the beach, some of the wave soaks into the sand depositing material on the beach
• The weaker backwash then returns to the sea
• They are low energy waves that are also flat and low, less than 1m high
• Constructive waves are most common during summer time

Destructive Waves

• Backwash is stronger than the swash
• Tall, powerful waves break rapidly and plunge onto the beach
• The stronger backwash drags the material back out to sea, eroding the coastline
• The backwash returns quickly without soaking into the sand
• Destructive waves are most common during winter time

Wave Refraction

• Wave Refraction is when waves bend and change their direction as they approach the shore
• As the waves reach the coastline, the headland is encountered first
• As they enter shallow water, they begin to slow down near the headland
• In deeper water the waves continue at greater speeds
• This difference in speed causes the waves to bend inwards around either side of the headland
• The erosive power of the wave is concentrated on the headland, so erosion mainly occurs here
• It is less powerful when it reaches bays, so deposition occurs