GEOGRAPHY PAPER 3
Coasts
Coastal processes
Waves
Size depends on: wind speed, length of time wind blows in constant direction and
length of fetch
California: very big waves as come from Aleutian Islands, 4000m fetch so time for
wave energy to build up.
Mediterranean: very small waves as surrounded by islands so reduced fetch
available for wave generation.
wave form moves, water particles rotate in circular/elliptical movement. energy of
wave that moves towards shore. when wave breaks, energy translates into
movement of water towards shore.
Terminology
wave crest: top of the wave
wave trough: bottom of the wave
wave height: difference in height between crest and trough
wave length: distance between two crests
wave period: time taken for wave to travel through one wave length
wave velocity: speed of movement of wave crest. av wave length / av wave period
wave frequency: no. of waves that break on beach in given period of time
wave steepness: wave height / wave length. cannot exceed 1:7 as wave will break
wave energy: energy is proportional to wave length, multiplied wave height
squared. wave energy directly related to height; energy released when wave
breaks
plunge line: point at which wave breaks
swash: foaming water that rushes up beach when wave breaks, obtains energy
from energy released by breaking wave
backwash: water which returns down beach after wave has broken
Types of wave
wide, gently sloping beach can absorb wave energy so protects coastline.
if waves break against cliff/sea wall, wave energy directed at vertical surface,
effective erosion.
high energy waves: strong winds blowing onto coastline can produce storm waves.
when they break on steep sloping beach, plunging breakers are produced. example
of destructive waves.
destructive waves: remove sediment from beach. steep high waves. short wave
length. high wave frequency. weak swash and strong back wash. sediment
removed builds up as longshore bars near low tide mark.
low energy waves: if wind dies down over ocean, waves move in same direction
until reach coastline. wave height decreases and wave length increases. swell
waves when reach shore. smooth crest when approach coast, wave slides up beach
even if steep. called surging breakers. example of constructive waves.
Coasts
Coastal processes
Waves
Size depends on: wind speed, length of time wind blows in constant direction and
length of fetch
California: very big waves as come from Aleutian Islands, 4000m fetch so time for
wave energy to build up.
Mediterranean: very small waves as surrounded by islands so reduced fetch
available for wave generation.
wave form moves, water particles rotate in circular/elliptical movement. energy of
wave that moves towards shore. when wave breaks, energy translates into
movement of water towards shore.
Terminology
wave crest: top of the wave
wave trough: bottom of the wave
wave height: difference in height between crest and trough
wave length: distance between two crests
wave period: time taken for wave to travel through one wave length
wave velocity: speed of movement of wave crest. av wave length / av wave period
wave frequency: no. of waves that break on beach in given period of time
wave steepness: wave height / wave length. cannot exceed 1:7 as wave will break
wave energy: energy is proportional to wave length, multiplied wave height
squared. wave energy directly related to height; energy released when wave
breaks
plunge line: point at which wave breaks
swash: foaming water that rushes up beach when wave breaks, obtains energy
from energy released by breaking wave
backwash: water which returns down beach after wave has broken
Types of wave
wide, gently sloping beach can absorb wave energy so protects coastline.
if waves break against cliff/sea wall, wave energy directed at vertical surface,
effective erosion.
high energy waves: strong winds blowing onto coastline can produce storm waves.
when they break on steep sloping beach, plunging breakers are produced. example
of destructive waves.
destructive waves: remove sediment from beach. steep high waves. short wave
length. high wave frequency. weak swash and strong back wash. sediment
removed builds up as longshore bars near low tide mark.
low energy waves: if wind dies down over ocean, waves move in same direction
until reach coastline. wave height decreases and wave length increases. swell
waves when reach shore. smooth crest when approach coast, wave slides up beach
even if steep. called surging breakers. example of constructive waves.
