geography paper 1

• Constructive waves


  • Strong swash, weak backwash
  • Low wave height, large wavelength
  • Low frequency
  • Depositional - the waves leave material on the beach, and so build up the material (sand, pebbles, etc) over time

  
• Destructive waves


  • Strong backwash, weak swash
  • High wave height, small wavelength
  • High frequency
  • Erosional - the waves erode the beach and any rocks and take the material away to other locations. Over time, the beach wears away

  
• Factors affecting wave size

  • Strength of the wind
  • How long the wind has been blowing for
  • Water depth
  • Fetch - the distance the waves have travelled from where they originated from

  
• Coastlines hit by constructive waves


  Tend to have depositional landforms such as sandy beaches

  
• Coastlines hit by destructive waves


  Typically have erosional landforms such as rocky headlands and landforms, such as tall cliffs and caves

  
• Coastal processes


  • Erosion
  • Weathering
  • Transportation
  • Mass movement
  • Deposition

  
• Corrasion


  Sand and pebbles are picked up by the sea and hurled against the cliffs at high tide, causing the cliffs to be eroded. The shape, weight and quantity of sediment picked up, as well as the wave speed, affects the rate of erosion

  
• Erosional landforms


  • Wave-cut notch
  • Wave-cut platform

  
• Longshore drift


  Sediment is transported along the coast through the process of longshore drift

  
• Longshore drift


  1. Waves hit the beach at an angle determined by the direction of the prevailing wind

  2. The waves push sediment in the direction of the prevailing wind up the beach in the swash

  3. Due to gravity, the wave then carries sediment back down the beach in the backwash

  4. This moves sediment along the beach over time

  
• Deposition


  Occurs when a wave loses energy meaning the sediment becomes too heavy to carry
• Depositional landforms


  • Beaches
  • Spits
  • Bars
  • Sand dunes
• Berm


  Ridges where high tide reaches and deposits a ridge of sand and materials (seaweed, driftwood, etc)

  
• Spit


  A long narrow strip of land which is formed due to deposition. Longshore drift occurs along the coastline but as the waves lose energy (normally due to going into a sheltered area such as behind a headland) they deposit their sediment. Over time this creates a spit

  
• Bar


  Bars can form from spits, but only in certain locations. A bar is a spit that has grown across the mouth of a bay. This cuts off the sea water from the bay, creating a lagoon with still water and over time this will become a freshwater lake
• Yellow dunes form as more sand accumulates and the dunes become more vegetated
• Recurved spit end


  A spit that has grown across the mouth of a bay, cutting off the sea water and creating a lagoon
• Bar formation


  1. Spit grows across the mouth of a bay

  2. Cuts off sea water

  3. Creates a lagoon

  4. Over time becomes a freshwater lake
• Barrier beach


  A spit that grows straight out to an island, joining it up to the mainland
• Weathering


  The breakdown of rocks over time, producing material which creates coastal landforms or sediment taken away through transportation

  
• Types of weathering processes

  • Mechanical (Physical) Weathering
  • Chemical Weathering
  • Biological Weathering
• Carbonation


  Acid rain reacts with calcium carbonate in rocks to form a chemical compound which can then be easily dissolved
• Hard engineering


  Uses man-made, artificial structures to reduce or halt erosion
• Soft engineering


  Uses more natural materials to reduce erosion, in a more environmentally friendly way
• Managed retreat


  Allows erosion rates to carry on unchanged, monitoring the rate of erosion and putting ways of adapting to this erosion in place for the future
• Factors to consider when choosing coastal management strategy


  • Economic value
  • Cultural/social value
  • Environmental value
• Soft engineering methods


  • Dune stabilisation
  • Beach nourishment
• Hard engineering methods


  • Groynes
  • Sea walls
  • Rip rap (rock armour)
  • Revetments
• Drainage basin


  An area of land drained by a river and its tributaries with a boundary (known as the watershed), which are usually hills and mountains
• Upper course


  • Tributaries are narrow and v-shaped
  • Low volume of water
• Friction between water and riverbed


  Slows the water down
• Larger river channel


  Less water is in contact with riverbed, increasing velocity
• Abrasion


  Rocks carried by water scrape and bang against the sides of the river, wearing away the channel
• Attrition


  Rocks and pebbles hit against each other, wearing each other down and becoming round and smaller
• Hydraulic action


  Water under high pressure causes cracks to force apart and widen in rocks along the banks
• Corrosion (solution)


  River can gradually dissolve chemical compounds in rocks it flows over
• Types of transportation


  • Solution
  • Suspension
  • Saltation
  • Traction
• Heaviest materials get deposited first in upper course, finer sediment travels to lower course
• Most deposition occurs in the lower course of the river
• Landforms in each river course

  • Upper course: Waterfalls, Interlocking Spurs, V-Shaped Valley
  • Middle course: Gorges, Meanders
  • Lower course: Floodplains, Ox-Bow Lake, River Estuary