coastal environments

• hydraulic action is the force of water pushing against the rock and air gets trapped in cracks causing it to break
• abrasion is when rocks are launched against cliff face during high energy conditions, weakening structure
• solution/corrosion: the dissolving of soluble rocks by seawater
• attrition is when particles roll over each other due to friction and strong wave action
• solution is when dissolved material is carried in water
• suspension is when fine sediment is carried in water, making the water look murky
• saltation is when small pebbles bounce along the seabed
• traction is when larger, heavier material are dragged along seabed
• sliding refers to the downhill movement of large material on steep hillsides and cliff faces after heavy rainfall has weakened the slope
• rotational slumping often occurs after long periods of rainfall which seeps through the soil. where the permeable rock meets an impermeable rock, the saturated rock slumps and slips along a curved surface.
• rockfalls happen suddenly when pieces of rock fall from a cliff that has been weathered or undercut by wave action
• chemical weathering (solution) is the breakdown of rocks by chemical reactions in the atmosphere. Water reacts with CaCO3 in rocks which dissolves and is washed away, weakening the rocks
• mechanical weathering (freeze thaw)

  1. water gets trapped in crack in rock
  2. when temperature is really cold, water freezes and expands, putting pressure on rock
  3. process repeats and further weakens the rock
• biological weathering (root action) is the breakdown of rocks by living organisms, such as bacteria and fungi

  1. plant roots can enter a small crack in a rock
  2. as the root grows larger the crack in the rock gets larger
  3. weakens the structure of the rock until it eventually breaks away
• coastal erosion is the wearing away of land at the coastline
• wave refraction is the bending of waves around headlands and spits
• • Longshore drift is the process where the waves transport material (sand) along the beach in the direction of the prevailing wind 
  • swash moves material up the beach at an angle, as the waves approach in a similar direction to the wind
  • backwash moves back down the beach at 90° due to gravity in the direction of the prevailing wind 
  • movement continues at 90 degree angle

  
• influence of geology on the coast

  • headlands are more resistant to erosion since they're made out of hardrock- juts out
  • bays are less resistant and erode quicker because they're made out of softrock
  • causes differential erosion
• influence of vegetation on the coast

  • brings stability to low energy coasts
  • allows flocculation- binding of sediment in big clusters when it's too heavy to carry by wind/water
  • plants protect sediments from current speeds and erosion
• influence of people on the coast

  • housing for commuters
  • agriculture destroys habitats for space to grow crops
  • coral mining ruins coral reefs
  • dynamite fishing causes coastal erosion and beach degradation
• influence of sea level changes on the coast

  • can destroy agriculture and coasts
  • global warming -> thermal expansion and ice sheets melting -> sea levels rise (eustatic change)
  • more frequent storms -> wave energy moves inwards onshore -> erosion of cliffs
• constructive waves have

  • a strong swash but weak backwash
  • long wavelength, low in height and frequency
  • sandy beaches (depositional)
• destructive waves have

  • weak swash but strong backwash
  • short wavelength but high in height and frequency
  • shingle beaches (erosional)
• conflicts on coast

  human needs (development) vs well being of coastal ecosystems (conservation)

  development (farmers and fishermen): provides more jobs to boost economy, more houses to support population and more ports for trade to increase GDP

  conservation (environmentalists): protects wildlife by acting as a coastal barrier and brings more tourism
• what causes coastal flooding

  • high tides: periodic- happen nearly everyday, worse when combined with storm surges, threatens infrastructure and agriculture
  • sea level rise: increased global warming = thermal expansion
  • storm surges: rising sea levels = frequent flooding = severe storms, scale and height are intense making it a huge threat
  • tsunamis: infrequent but predicted by seismometers
• The Holderness coastline is located on the east coast of England and is the fastest eroding coastline in Europe (1.8m each year)
• Reasons for rapid erosion at Holderness

  • Rock types - cliffs are made from less-resistant boulder clay which slumps when wet
  • Narrow beaches- give less protection to the coast as they don't reduce the power of the waves.
  • Hard engineering- groynes stop LSD and build up the beaches which narrows unprotected beaches as new sand does not replace sand eroded by waves.
  • Powerful waves - travel long distances over the North Sea (so have a long fetch) which means they will increase in energy.
• Management strategies

  • Bridlington is protected by a 4.7 km long sea wall.
  • Hornsea is protected by a sea wall, groynes and rock armour.
  • Coastal management at Withernsea has tried to make the beach wider by using groynes, and a sea wall to protect the coast.
  • Mappleton is protected by rock groynes.
  • Spurn Head is protected with groynes and rock armour.
• conflicts

  • There has been an increase in erosion at Mappleton because the groynes used leads to farms being destroyed by erosion
  • Some people disagree with where the sea defences have been located, especially if land in their community is not protected.
  • Some sea defences negatively impact tourism and reduce the amount of money coming in to the area.
• erosional processes are hydraulic action, abrasion, attrition and solution
• mass movement is when rocks loosen and fall down a slope due to gravity (rotational slumping, sliding and rockfall)
• weathering is the breakdown of rocks by natural processes, such as water, and wind (biological, chemical and mechanical)
• what are the 4 ways sediment can be transported along a beach

  solution, suspension, saltatation and traction