Waves:
Key words:
● Crest = the top of a wave
● Trough = the base of a wave
● Wave height = the vertical distance from trough to crest
● Wavelength = the horizontal length between 2 successive crests
● Wave frequency = the number of waves per minute
● Fetch = the maximum distance of open sea that the wind can blow over
Causes:
● Waves are caused by the transfer of energy from the wind to the sea
● They shape coastal lines through erosion and deposition
○ Erosion = the wearing away/removal of material by a moving force, such as a breaking wave
○ Deposition = process in which sediments, soil and rocks are added to a landform or land mass
● eg/ Hampshire and Dorset coast
Strength of waves:
→ The amount of energy in a wave depends on:
● The speed of the wind
○ Strong winds result in stronger waves because more energy is transferred
● How long the wind has been blowing
○ The longer the wind has been blowing, the more energy the waves obtain
● The fetch
○ The greater the fetch, the greater the possibility of larger waves
Constructive waves:
● Found in sheltered bays and spits where they
build up sandy beaches
● More common in summer than in winter
● Long wavelength = low frequency
○ 8 – 10 waves per minute
● Low wave height → under 1 m
● Low energy → wave loses energy from friction
with the sand
● Process:
1. Swash spills over covering a large area
of the beach
2. Wave loses energy as it is in friction
with the sand
3. Some of the water soaks into the sand
4. Swash is stronger that it’s backwash
● Swash > backwash
○ Build up beaches rather than
destroying them
Destructive waves:
● Found in more exposed bays where they build
up pebble beaches
● More common in winter than in summer
● Short wavelength = high frequency
○ 10 – 14 waves per minute
● High wave height → over 1 m
● High energy
● Force generated by a destructive wave can
also erode a headland
● Backwash > swash
○ Can comb beach material back into
the sea and lower beaches in