Rivers

• 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
• River stages


  • Upper course
  • Middle course
  • Lower course
• Upper course

  • Tributaries are narrow and v-shaped
  • Low volume of water
• Middle course

  • Channel is rounder in shape and deeper than upper course
  • More energy due to higher volume of water
  • Floodplain around river channel
• Lower course

  • Largest volume of water in a very wide and very deep channel
  • Ridges either side of river banks called Levees
  • Valley is wider and flatter than middle course
• Friction between water and riverbed

  Slows down the water
• More contact between water and riverbed

  More friction, slower rate of flow
• Less contact between water and riverbed

  Less friction, faster velocity
• Vertical erosion

  Erosion that occurs downwards on the river bed
• Lateral erosion

  Erosion that occurs sideways along the banks of the river
• Types of river erosion

  • Abrasion
  • Attrition
  • Hydraulic action
  • Solution

  
• Types of river transportation

  • Solution
  • Suspension
  • Saltation
  • Traction

  
• Deposition occurs when the water in a river decreases in speed
• Deposition is the dropping of the river's load
• Heaviest materials get deposited first in the upper course, finer sediment travels to the lower course
• Most deposition occurs in the lower course of the river
• Typical 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

  
• Interlocking Spurs

  • Found in upper course where water doesn't have a lot of energy
  • River re-routes and curls around resistant rocks
• Formation of Waterfalls


  1. River flows over rocks with different resistances to erosion

  2. Soft rock erodes more quickly

  3. Soft rock erodes away around hard rock over time, creating a step

  4. Soft rock continues to erode, undercutting the hard rock

  5. Hard rock is left suspended in the air as an overhang

  6. Rotational movement of water quickens erosion, creating a deep plunge pool

  7. Unsupported overhang collapses, broken rocks fall into plunge pool

  8. Erosion continues to undercut underneath the hard rock, creating an overhang again further upstream

  9. Continual process of overhang collapsing causes the waterfall to retreat upstream over time

  
• Gorges


  Steep valleys carved into rock by retreating waterfalls

  
• Banbury Case Study

  Historic market town in the south-east of England, located within an hour's drive of London, Birmingham and Oxford
• Banbury


  • Influential to local and national trade since the medieval ages
  • Close proximity to three major UK cities
  • Prime location for businesses and commuting workers
• Banbury was destroyed during major flooding in 1998
• Further flooding has happened again in Banbury
• This has resulted in government strategies and management of the local river, which has benefited the town's recovery but has come at a cost for its environment
• River that flooded

  River Cherwell
• Date of Flooding

  Easter 1998
• Cost of Damages = £12.5 million
• Lives Lost = 0
• People forced to evacuate = 350
• Schemes to reduce the risk of flooding

  Benefited the economy and allowed the town to develop
• Costs of the schemes

  • Social
  • Environmental
  • Economic
• Social benefits


  • House owners no longer worried about damage to their property
  • Uninsured houses especially at risk during flooding
  • New footpaths and parks surrounding the flood water storage
  • Improved quality of life for dog walkers and families
• Environmental costs


  • Biodiversity plan will increase vegetation to reduce risk of flooding
  • Heavy machinery damaged nearby vegetation during construction
  • Soil removed from areas surrounding Banbury to make embankments, disrupting habitats and wildlife
• Economic costs and benefits

  • Construction work cost £18.5 million
  • Construction jobs created
  • Jobs to maintain the biodiversity plan
  • Estimated £100 million saved in avoiding damages