Coastal landscapes

• Backshore


  The area between high watermark and the landward limit
• Foreshore


  The area between the high water mark and the low water mark
• Nearshore


  The area between the low water mark and the point where the waves don't really have any influence
• Offshore


  The point beyond where the waves cease to impact upon the seabed
• Coast should be seen as a system with flows, inputs and stores
• Inputs to the coastal system come in the form of wind, waves, sea currents and tides
• Wave movement at the beach

  1. Friction in the seabed slows the wave

  2. Wave crest continues to move forward

  3. Elliptical orbit of wave

  4. Wave rushes up the beach as swash and returns as backwash
• Constructive waves


  Have a low wave height, low frequency, weak backwash but strong swash
• Destructive waves


  Have a higher wave height, higher frequency, powerful backwash
• Wave refraction


  1. Waves bend towards shallower water

  2. Quicker the change in water depth, the quicker the refraction
• Longshore drift


  1. Prevailing wind pushes wave up the beach at an angle

  2. Sediment is dragged back out to sea

  3. Picked up by prevailing wind and waves push it back up the beach
• Rip currents


  Strong currents that move away from the shoreline
• Tide


  Periodic rise and fall of the sea level
• Spring tide


  Tide just after new or full moon
• Neap tide


  Tide just after the first or third quarters of the moon
• Tidal range


  Difference between high and low tide
• Macro


  Large scale
• Micro


  Extremely small scale
• High energy coastline


  Wave energy is high, erosion is likely to be greater
• Low energy coastline


  Wave energy is typically lower, deposition is normally greater
• Coastal processes


  • Marine processes (erosion, transportation, deposition)
  • Sub-aerial processes (weathering, mass movement)
• Coastal landforms


  • Caves
  • Arches
  • Stacks
  • Stumps
  • Wave cut notches
  • Wave cut platforms
• Beach features


  • Runnel
  • Cusps
• Simple spit


  Spit that goes out roughly parallel to the coast
• Compound spit


  Spit with occasional changes in the dominant wind process, resulting in a hooked or curved feature
• Bar


  Ridge of sand and shingle which joins up to headlands, often cutting off a bay behind which a lagoon forms
• Mud flats


  Found at the edges of permanently submerged marine zones, susceptible to changes in sea level, wave action, river volume and tidal flows
• Salt marshes


  Develop from mud flats in sheltered shorelines with river estuaries, salt water and fine sediment
• Eustatic sea level change

  Caused by volume of water in the sea or by the change in the shape of the ocean basin
• Isostatic sea level change

  Caused by vertical movements of the land relative to the sea
• Submergent coastline


  Stretches along the coast that have been inundated by the sea due to a rise in sea level
• Emergent coastline


  Coast that has been exposed due to a fall in sea level
• Submergence landforms


  • Rias
  • Fjords
• Emergence landforms


  • Raised beaches
  • Marine platforms
  • Relict cliffs
• Shoreline management plan


  Developed as part of the UK government's efforts to make coastal management more sustainable, matching up with sediment cells
• Shoreline management options


  • Hold the line
  • Managed realignment
  • No active intervention
  • Advance the line
• Integrated coastal zone management


  Integrates and views the environment as a whole, considering different uses and involving authorities at local, regional and national levels
• The Sundarbans is one of the largest mangrove forests in the world, facing threats from climate change, industrial projects and destructive human activities
• Approaches to managing threats in the Sundarbans

  • Develop resilience
  • Mitigation
  • Adaptation
• Tidal barrier


  a barrier that traps water at high tide, creating a tidal basin