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SYSTEMS (Physical Factors (Waves (Breaking Waves (3 types (Spilling -…

- - - - These are Aeolian processes and contribute to the shaping of coastal landscapes
  - - - P = power in kilowatts per metre of wave front
      - H = wave heght in metres
      - T = time interval between wave crests in seconds, (wave period)
      - Relationships between wave height and wave energy is non-linear
      - Wave height is a more important factor in determining wave energy than wave period bc Atlantic waves and 8 times higher than Channel waves, but have 70 times more energy
    - - The crest is the highest surface part of thee wave
      - The trough is the lowest part of a wave
      - Wave height is the vertical distance between the crest and the trough
      - Wave length is the horizontal different between two adjacent troughs/crests
      - Wave behaviour is influenced by many factors e.g. shape and gradient of sea floor and irregularity of coastline
      - Waves formed in open oceans can travel huge distances
        
        These are swell waves nad have a long wavelength with a wave period of up to 20 seconds
      - A local generated storm wave has a short wavelength and a shorter wave period
    - - Shallow water is at a depth of half the wavelength
      - In shallow water, the deepest circling water molecules come into contact witht he seafloor
        
        Friction between seafloor and water = changes between:
        
        Spped
        
        Direction
        
        Shape
      - Waves slow down as they drag across the bottom of the seafloor
      - Wavelength decreases and successive waves bunch together
      - Deepest part of the wave slows down more than the top of the wave
      - Wave beings to steepen as the crest advances ahead of the base
      - Water depth is less than 1.33 * wave height = wave topples over and breaks against the shore - at this point there is significantly forwards movement of water as well as energy
      - 3 types
        
        Spilling - steep waves breaking onto gently sloping breaches; water spills gently forward as the wave breaks
        
        Plunging - moderately steep waves breaking onto steep beaches; water plunges vertically downwards as the crest curls over
        
        Surging - low-angle waves breaking onto steep beaches; the wave slides forward and may not actually break
      - After wave has broken, it moves up the beach as swash - driven by the transfer of energy that occurs when it break
      - Water is pulled back down the beach as backwash when the energy carrying the swash up the beach has been used. The energy for backwash comes form gravity and always occurs perpendicular to the coastline, down the steepest slope angle
    - - Constructive
        
        Low in height
        
        Long wavelength
        
        Low frequency - 6-8/minute
        
        Break as spilling waces
        
        Strong swash travels a long way up the beach
        
        Long wavelength = backwash returns to sea before next wave breaks = next swash movement is uninterrupted and thus retains its energy
        
        Swash exceeds backwash energy
      - Destructive
        
        Greater height
        
        Shorter wavelengths
        
        Higher frequency - 12-14/minute
        
        Break as plunging waves = little forward transfer of energy to move water up beach as swash
        
        Friction from beach slows down swash, so it does not travel far before travelling down beach as backwash
        
        Short wavelength = swash of enxt wave is slowed by frictional effects of meeting the returning backwash of the previous wave
        
        Swash energy is less than backwash
      - Beach gradient and wave type
        
        High energy waves remove material from the top of a beach and transport it to the offshore zones = reduced beach gradient
        
        Low energy waves build up the beach face, steepening the profile
        
        Factors
        
        Wave steepness
        
        Angle of wave apprach
        
        Sediment size particle
  - - - At locations between the 2 bulges, there will be low tide
      - As the moon orbits the earth, high tides follow it
    - - Occurs twice each lunar month = spring tides nad high tidal range
    - - Enclosed areas e.g. Mediterranean, tidal ranges are low = wave action restricted to narrow area of land
        
        Tidal ranges can be as high as 14m in areas where the coast is funnelled e.g. Severn Estuary
      - Tidal range influences:
        
        Where wave action occurs
        
        Weathering processes that happen on land exposed between tides
        
        Potential scouring effects of waves along coasts with a high tidal range
  - - - Physical and chemical composition of rocks
      - Weak lithology = little resistance to erosion, weathering processes + mass movements e.g. clay
        
        Bonds between the particles that make up the rock are quite weak
      - Strong lithology e.g. basalt = resistant to erosion, weathering, mass movements = formation of prominent coastal features e.g. cliffs and headlands
        
        Made of dense interlocking crystals
      - Chalk and carboniferous limestone are made mostly of calcium carbonate = vulnerable to chemical weathering processes e.g. carbonation
    - - Properties of individual rock types
        
        Joingting
        
        Bedding
        
        Faulting
        
        Permeability
        
        In porous rocks, pores separate the mineral particles and are able to store and absorb water - this is primary permeability e.g. chalk
        
        Water seeps into limestone because of its many joints, the joints are easily enlarged by solution = other form of permeability
      - Regional planform of coast
        
        Rock outcrops that are uniform or run parallel to the coast = straight coastlines - CONCORDANT
        
        Rocks that lie at right angles to the coast are DISCORDANT - more resistant rocks form headlands; weaker rocks = bays
      - Angle of dip of rocks
        
        Influences cliff profiles
        
        Horizontally-bedded and landward-dipping strata support sliffs with steep, vertical profiles
        
        When strata inclines seawards, cliff profiles tend to follow the angle of the bedding planes
- - - - Major sources of sediment input
      - Input is increased by coasts with a steep gradient where rivers directly deposit their sediment at the coast
      - Sediment delivery to shoreline is intermittent
        
        Mostly occurs during floods
      - Provides 80% of coastal sediment in some locations
    - - Increased by rising sea levels
      - Amplified by winter storm surges
      - Weak cliffs in high energy environments = 70% of overall materials supplied to beaches
      - Some sediment comprises large rocks and boulders - especially if derived from collpase of undercut cliffs
    - - Supplies sediment from a coastal area by moving it along the coast
  - - - Cliff erosion
      - River sediment
    - - Dunes
      - Beaches
      - Nearshore sandbanks
      - Offshore sandbanks
    - - LSD
      - Offshroe transport
      - Onshore transport
      - Aeolian transport from the coastal zone
  - - - This aeolian material consists of fine sands coz wind has less energy
- - - - Kinetic energy from wind and waves
      - Thermal energy from sun's heat
      - Potential energy from the position of material on slopes
      - Material from marine deposition, weathering and mass movements from cliffs
    - - Marine and wind erosion from beaches and rock surfaces
      - Evaporation
    - - Stores e.g. beach + nearshore sediment accumulations
      - Flows/transfers e.g. movement of sediment along a beach by LSD
  - - - This is an example of negative feedback bc the system produces its own response to the disturbance