Coasts

• What type of coastlines can sea level changes create?

  Submergent - when sea levels rise

  Rias

  Fjords

  Dalmation coasts

  
  

  Emergent - when sea levels fall

  Raised beaches

  Relict cliffs

  Wave cut platforms
• How have rising sea levels impacted coastal areas?

  Storms are becoming more frequent which damages ecosystems and settlements

  
  

  More frequent and severe flooding

  
  

  Submergence of low lying islands; for example, if sea level rises by 0.5M then The Maldives will be fully submerged.

  
  

  Contamination of water and farmland from sea water entering bodies of fresh water.

  
  

  Increased amounts of coastal erosion
• How has climate change affected sea levels?

  Increases in temp are likely to cause increases in sea level, through melting of ice sheets and thermal expansion of water in oceans occurs.

  
  

  Sea level is currently rising at 7mm per year. If greenhouse emissions stay at their current rate then this rate will rise to around 8-16mm by 2100.
• What is isostatic sea level change?


  Local changes in sea level, downward movements of land can cause sea levels to rise and uplift can decrease sea levels.

  
  

  Uplift may occur due to melting of ice sheets, this may occur over thousands of years after the weight of the glacier has gone.

  
  

  Tectonic processes such as one plate forced beneath another.
• What is eustatic sea level change?

  Global changes in sea level

  
  

  An increase in global temp can melt ice sheets which increase sea level and cause water to expand increasing it further.

  
  

  A decrease in global temp could cause more precipitation as snow which increases the volume of water stored in the glaciers and decreases amount store in the sea.

  
  

  Sea floor spreading can decrease sea levels.
• What are the types of the marine transportation?

  Solution -> fine soluble rocks are dissolved and transported via the water.

  
  

  Suspension -> fine material and small particles are whipped up by ocean turbulence and carried in water

  
  

  Saltation -> larger heavier particles are bounced along the sea bed.

  
  

  Traction -> large particles are too heavy to be so they're rolled along the sea bed
• What are the types of deposition and what can affect it?

  Marine deposition is when sediment carried by sea water is deposited.

  
  

  Aeolian deposition is when sediment carried by wind is deposited.

  
  

  Sediment load is what causes the water and wind to lose ability to carry it. For example, an increase in friction when water enters shallow areas or wind reaches land.
• What is salt weathering?

  When saline water enters cracks in the rocks and when the tide eventually goes back out, the water evaporates. When this occurs it forms salt crystals which then expand and in turn weather the rock and break it off.
• What is freeze-thaw weathering?

  In areas where temps drop below 0°c this can occur. Water enters crack in the rocks and as temperatures drop below 0°c the water freezes and expands; as it does this put pressures on expanding rock and weathers it then potentially causing rocks to fall out.
• What is biological weathering?

  The breakdown of rocks due to living organism. For example, lichens grown on the rocks and then they release chemicals that break down the rocks.
• What is chemical weathering?

  The break down of rocks by changing its chemical composition. For example, as C02 mixes with water vapour in the atmosphere to create weak carbonic acid. These acids can break down certain types of rocks such as limestone of which it gradually dissolves.
• What is mass movement?

  The shifting of material down-hill due to gravity. In coastal areas, this can occur when cliffs are undercut by waves, forming a wave cut notch which creates an unsupported overhang which eventually collapses
• What are the types of mass movement?

  Slides -> Material moves in a straight line

  
  

  Slumping -> Material moves with a rotation

  
  

  Rockfalls -> Material breaks up and falls

  
  

  Mudflows -> Flows downslope

  
  

  Material can also gradually go downwards because of soil creep.
• Which rocks are prone to collapse?

  Unconsolidated rock as there is little friction between the particles. Also, heavy rain saturates the unconsolidated rock making it even more prone to collapsing
• What is "wetting" and "drying" ?

  Some rocks contain clay, as clay gets wet it expands and the pressure of this causes fragments of the rock to break off.
• What are the types of erosion?

  Hydraulic Action -> Sheer force of the waves hitting the cliff

  
  

  Abrasion -> Boulders and rocks hitting the cliff face and weakening it

  
  

  Wave quarrying -> Water from waves go into cracks in the rock and pressure builds up. As pressure is released this can create an explosive effect and there in weaken the cliff and break parts off

  
  

  Attrition -> When rocks collide in the water and break down into smaller rocks

  
  

  Solution -> Very fine material gets dissolved by the water
• Where is Formby located and what are the characteristics?

  North West England in Merseyside

  
  

  In the 20th Century the coastline lost 700m between the years of 1920 and 1970

  
  

  Largest dune system in England
• What causes erosion on Formby beach?


  Periodic storms and high tides

  Trampling

  Use of land vehicles

  Digging material for local use

  Hard sea defenses in Southport causing erosion damage
• What been done to protect Sefton coast?

  Sefton coast management scheme was introduced in 1980

  
  

  Planted Christmas trees at the seaward edge of the dunes

  
  

  Fencing off areas to prevent trampling

  
  

  Wooden posts at the edge of the dune to encourage growth and deposition - dune regeneration

  
  

  Building boardwalks to prevent trampling

  
  

  Banning off road vehicles

  
  

  Controlling extraction for commercial use
• How have golf courses helped Sefton coast?

  Occupy over a quarter of the dune area and are important areas for wildlife as it is associated with rare species such as sand lizards.

  
  

  Also useful to conserve a semi-natural dune land environment.

  
  

  Also allows floods to flood naturally - not costly to replace.
• What are currents?


  The permanent / seasonal movement in sea surface water

  
  

  Winds that blow along the shoreline, longshore winds affect waves and therefore currents.

  
  

  There are different types of currents such as longshore currents and rip currents.
• What are tides?


  The periodic rise and fall in sea level caused by the gravitational pull of the moon and sun. The moon has the biggest influence as it is closer, pulling the water towards it creating high tide.
• What is spring tide?

  Occurs 2 times a lunar month when the sun, moon and earth are in a straight line ; the ride raising force is strongest and this is the highest monthly tide.
• What is neap tide?

  Occurs 2 times a lunar month when the sun and moon are at 90° to the earth. At this point high and low tides are 10% - 30% which are lower than usual.
• What is tidal range and how can it affect the beach?

  Tidal range is the difference in height of sea water at high tide compared to low tide

  
  

  This can determine the upper and lower limits of erosion and the length of time the littoral zone is exposed to subaerial weathering
• What are some examples of tidal range?

  Mediterranean -> tidal range is low which restricts wave action

  
  

  British isle -> tidal range are high giving a wide zone of wave attack
• What are tidal surges?

  There are occasions (stormy weather), when the meteorological conditions give rise to strong winds which can produce much higher water levels then those at high tide. E.G. British Isles
• What are longshore currents?

  Winds approach the beach at an angle causing waves to approach the beach at an angle. This creates a flow of water (current) running parallel to the coastline.
• What are rip currents?

  A localised current caused by a build up of water at the top of the beach, the backwash is then forced under the surface due to resistance from breaking waves forming an underwater current. This flows away from the beach more quickly due to beach features e.g. sand bar creating a rip current.
• Where is Holderness Coast located?

  East Yorkshire, stretching from Spurnhead to Flambough head.

  
  

  North of the coast experiences a lot of erosional processes such as cliff wave cut platforms.

  
  

  The south is more depositional such as beaches and spits.
• What possible schemes are there for Holderness?

  The SMP for Holderness has been there for 50 years which suggests that holding the line of areas with highly populated areas which has caused tension with land owners with property there.
• What problems have incurred at Holderness management schemes?

  Groynes -> Trap sediment from longshore drift and starves the beach further downdrift of sediment causing erosion there. For example, the Mappleton Scheme used groynes in Mappleton and caused increased erosion on cliffs south.
• What management schemes have been used in Holderness?

  Groynes (Hornsea)

  Seawall (Hornsea and Withernsea)

  East of Yorkshire has a Sin Sea Wall

  A gas terminal is protected by revetment
• What are some impacts of erosion on Holderness?

  Loss of settlements and farmlands, 30 villages have been lost.

  
  

  Loss of infrastructure

  
  

  Loss of special scientific sites
• What are some examples of soft engineering strategies?

  Beach nourishment

  Managed retreat

  Doing nothing

  Land use management

  Dune regeneration
• What is beach nourishment?

  Redistributes new sediment in an attempt to replace material lost through longshore drift, erosion, storms etc.

  
  

  Enlarges the beach which distributes wave energy

  
  

  Sediment must not be taken from somewhere in the sediment cell.

  
  

  Costs are high
• What is managed retreat?

  Abandoning current sea defenses and developing land in some way such as salt marshes to distribute the wave energy.

  
  

  Lets beach do what it naturally does.

  
  

  Restricts building in some areas.
• What is "do nothing"

  Should coasts be protected?

  
  

  Storms in January in Devon showed hard engineering strategies to be ineffective.

  
  

  Should government spending be done elsewhere?
• What is land use management?

  Mitigate impacts from flooding by educating locals.

  
  

  Encourage land owners to think about how they can continue using land at lower risk such as caravan parks.
• What is dune regeneration?

  Sand dunes can be disrupted by human activities such as trampling.

  
  

  Replanting vulnerable areas such as marram grass.

  
  

  Stabilising ground by using wire mesh

  
  

  Afforestation

  
  

  Fencing

  
  

  Boardwalks / promenades