Lanforms and landscapes Flashcards
How are waves crated
friction between the wind and water -> transferring energy from wind -> water
-generates ripples -> grow- waves
What effects the size of the wave
- Strength of the wind,
- duration the wind blows for
- water depth
- wave fetch
What is the wave fetch
uninterrupted distance across water which a wind blows
How are waves affected by water depth
as the water shallows shape of waves change significantly
Explain the process of how a wave breaks
- when waves reaching shore reach a depth of 1/2 wavelength- internal orbital motion of water in wave touches sea bed.
- Friction ocurs between wave& sea bed -> slows down wave.
- As wave approaches shore -> wavelength shortens, wave height increases -> waves ‘bunch’ together.
- wave crest begins to move forwards much faster than wave trough
- wave trough experiences friction w sediment & rock
- wave crest outruns trough & wave topples forwards - breaking.
Give 6 characteristics of constructive waves
- Low energy waves -> spilling waves
- Low, flat wave height (<1m)
- Long wavelength (up to 100 m)
- strong swash -> pushes sediment up beach -> creating berm
- weak backwash
- constructs/ builds up the beach - beach gain
What is wave height
vertical distance from peak to trough
What is wave length
horizontal distance from crest to crest (or trough to trough)
What is wave frequency
number of waves passing a particular point over a given period of time
Give 6 characteristics of destructive waves
- High energy waves -> plunging waves
- Large wave height (>1 m)
- Short wavelength (about 20 m)
- weak swash
- strong backwash -> erodes material from beach
- destructs beach- beach loss
What is beach morphology
shape of the beach
What is a beach sediment profile
the pattern of distribution of different sized or shaped deposited material
Name 3 reasons why beach profiles may change over long periods of time
- sediment supply from rivers is reduced
- interference in sediment supply along coast
- changes to climate
What type of wave dominates in the winter
- > what is beach profile like?
- > what is beach like?
- > what landforms form?
- destructive, high-energy waves
- lowering angle of beach profile
- spreading shingle over the whole beach
- Offshore ridges/bars form
What type of wave dominates in the summer
- > what is beach profile like?
- > what is beach like?
- > what landforms form?
- constructive, low-energy waves
- steepening angle of beach profile
- sorting particles by size -> larger shingle particles towards back of beach
- berm
