Wave types - constructive and destructive

When the wind blows over the sea, it creates waves. The size and energy of the wave depends on certain factors:

  • the - how far the wave has travelled
  • the strength of the wind
  • how long the wind has been blowing for
Long fetch (up to 8,000 km) - South-westerly wind will produce large powerful waves. Short fetch (less than 200 km) - South-easterly wind will produce small waves.

Wave types

There are two different types of wave - constructive and destructive. They can affect the coastline in different ways. When a wave reaches the shore, the water that rushes up the beach is known as the . The water that flows back towards the sea is known as the . The energy of the swash and backwash determine the type of wave.

Destructive waves

Constructive waves are high in proportion to their length. They have a weak swash but a strong backwash. A tall breaker is a tall wave which breaks downwards with great force.

The characteristics of a are:

  • weak swash and strong backwash
  • the strong backwash removes from the beach
  • the waves are steep and close together

Constructive waves

Destructive waves are low in proportion to their height. They have a strong swash and weak backwash.

The characteristics of a are:

  • strong swash and weak backwash
  • the strong swash brings sediments to build up the beach
  • the backwash is not strong enough to remove the sediment
  • the waves are low and further apart