Chapter 1

Waves are created by wind blowing over the surface of the sea, creating friction, the energy in transferred which creates the waves

stronger wind-> greater friction-> higher and more powerful waves

• The effect of a wave on the shore depends on its height
• wave height is affected by the wind speed and the fetch of the wave
• fetch= maximum distance of sea the wind has blown over creating the waves
• a high wind speed and long fetch creates high waves

waves move across open ocean in a circular motion as a swell,

• as waves approach the shore they break, friction with the sea bed slows down the bottom of the waves and makes their motion more elliptical, the crest of the wave rises up and then collapses
• water washing up the beach/force= swash,
• water washing back= gravitational backwash

Amount of energy in a wave formula= H²T

• build up beaches
• long wavelength
• low frequency (about 6-8 waves per minute)
• they are long and low- gives more elliptical cross profile
• swash is quickly absorbed by the beach because of the low levels of energy
• sediment thrown up by the breaking waves accumulates in ridges or 'berms'
• backwash has little power to  move the sediment back towards the sea

• high and steep
• more circular cross profile
• higher frequency (10-14 waves per minute)
• wavelengths are shorter
• wave breaks at considerable height creating a large amounts of energy which cannot be easily absorbed by the beach
• powerful waves run up on the beach, the volume of water creating the opportunity for strong backwash to move sediment back down the beach and eventually out to sea.

Wave Period: time interval between successive waves crests arriving at a given point

Swell Waves: relatively smooth ocean wave that travels some distance from the area of its generation

Storm wave: wave generated locally by high wind energy

Swash: movement of water up a beach after a wave has broken

Backwash: flow of water down a beach after a wave has broken

Highest surface part of the wave is the crest, lowest is the trough. The vertical distance between the crest and the trough is the wave height. The horizontal distance between 2 adjacent crests or troughs is the wavelength.

Wave behaviour is influenced by many factors such as:

• gradient of sea floor
• irregularity of coastline.

Swell waves that have been formed in open oceans can travel huge distances-they generally have a long wavelength with a wave period of up to 20 secs.

Storm waves-generated locally, have shor wavelength, greater height and shorter wave period.