Coasts

• sediment cell: a length of coastline with a self contained sediment movement (closed system)
• sediment cells within the UK

  • 11 major cells
  • each cells has a input, store and output which produces a dynamic equilibrium
• sediment budget

  sediment enters - exited

  • positive = coastline grows
  • negative = coastline recedes
• coastal system inputs and outputs:

  • inputs - waves, tides, wind and pollution
  • outputs - oceans, currents and evaporation
• coastal transfers:

  • mass movement
  • weathering
  • erosion
  • transportation
  • deposition
  • long-shore drift
• coastal sediment sources and energy

  • sources - rivers, cliffs, long-shore drift, wind, glaciers
  • energy - wind, gravitational, flowing water and sun
• formation of waves:

  • air moves across the water making ripples which turns into a domino effect
• factors affecting wave energy:

  • strength and direction of wind
  • length of fetch
• constructive wave profile:

  • formed in open oceans
  • long wavelengths
  • strong swash, weak backwash
  • low waves and beach gain / summer waves
• destructive wave profile:

  • formed in located storm events
  • short wavelengths
  • weak swash and strong backwash
  • high waves and beach loss/winter waves
• negative feedback coastal loop:

  • constructive waves cause deposition producing steep slopes promoting destructive waves which erode the beach
• production of tides:

  • changes in sea level caused by gravitational pull of the moon and the sun
  • moon has a strong pull due to it being closer the earth
• Spring Tide:

  • highest tidal range when the sun and moon are aligned causing the most gravitational pull
• Neap Tide:

  • lowest tidal range when the sun and moon are perpendicular to each other both gravitational forces act against each other, but due to the moons stronger pull there's a slight higher tide
• rip currents:

  • when plunging waves/destructive waves cause a build up of water on the beach
  • backwash is forced below the breaking waves which can drag people into deep waters
• high energy coasts

  • powerful waves with rocky coasts
  • rate of deposition < rate of erosion
• Low energy coasts

  • constructive waves in sheltered coasts
  • rate of deposition > rate of erosion
• wave refraction

  • waves distort on uneven coastlines
  • wave energy is focused on headlands and dissipated in the bays