Rivers: a revision session

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Rivers a revision session
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River facts

• River landforms are formed by erosion,
  transportation and deposition
• The main processes of river erosion are
  abrasion, hydraulic action, attrition and
  solution. These operate best at times of flood.
• A rivers load is transported by solution,
  suspension, saltation and traction

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Parts of a rivers course

• A river can be subdivided into its upper, middle
  and lower course. Each part will have distinctive
  landforms and characteristics.
• Upper potholes, V shaped valleys, waterfalls and
  interlocking spurs.
• Middle slip off slopes, river cliffs, meanders
  and asymmetric cross section
• Lower flood plains, levees, ox bow lakes and
  deltas

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Flooding

• Rivers will flood when the discharge or flow is
  greater than the channel can cope with.
• Deforestation and the building of roads and
  houses on the flood plain increases surface
  runoff and reduces infiltration, increasing flood
  danger.
• Flooding can be reduced by building reservoirs,
  levees, and relief channels.
• Straightening the channel will increase the flow

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Flood management

• Two case studies
• MEDC Boscastle causes effects and solutions
• LEDC Mozambique, causes, effects and solutions.

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Future

• There has been a move away from hard solutions,
  e.g. the construction of levees to soft
  solutions e.g. flood plain zoning.
• This is particularly true in LEDCs where they
  cannot afford the costs of large schemes