Wave (geography)

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In Geography, waves occur in oceans, and are very important in the coastal system. There are two types of wave:

Constructive wavesEdit

  • Mainly deposit
  • Mainly operate in summer (when the wind isn't as strong and the waves are calmer)
  • Breaks gently, then swashes up the beach
  • Strong swash
  • Weak backwash
  • Gentle sloping beach profile
  • 6-9 waves/minute
  • 1-2m high
  • Shorter wave-lenght and higher wave frequency
  • Fetch distance is longer

Destructive wavesEdit

  • Mainly erode
  • Operate in storm conditions (most common in winter)
  • Created from big, strong waves when the wind is strong and has been blowing for a long time
  • Occur when wave energy is high and the wave has travelled for a long time
  • Tend to remove material from the coast and associated with erosion
  • Backwash is stronger than the swash.
  • 5-6m high
  • Steep sloped sandy beach
  • Wave frequency 10-15 per min
  • Fetch distance shorter

Formation of wavesEdit

Waves form because of the friction between the wind and the sea. The areas of high pressure become troughs and the areas of low pressure become the wave crests.

Breaking wavesEdit

Waves break when they are too steep to maintain their height. Near the coast waves steepen because of a fall in velocity because of friction with the seabed.

Wave energyEdit

Wave energy is generally affected by three main factors:

  • Wind speed - higher wind speed means more wave energy, because the energy is transfered from the wind to the wave.
  • Fetch - the distance of open water over which the wave has travelled across makes a big differenece on wave height and wave energy, as a longer fetch gives the waves longer to 'grow'.
  • Wind duration - with a longer storm, the waves will be bigger.

Wave energy and coastal enviromentEdit

How much energy the waves have will change how the coast looks:

  • High wave energy --> jagged cliffs, rocky coastlines, large boulders
    • Example: Cornwall
  • Medium wave energy --> sandy beaches, spits
    • Example: S.Coast
  • Low wave energy --> mudflats, salt marshes
    • Example: Norfolk coast

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