Rivers part 2

• What are the 4 types of erosion

  Abrasion, Attrition, Hydraulic action, Solution
• Hydraulic action


  The force of the moving water wears away the banks and bed of the river
• Solution


  Acids in the water dissolve the bed and banks
• Attrition


  material carried by the river bump into each other so are smoothed and broken down into smaller pieces
• Abrasion


  The bed and banks are wore down as the river throws rocks against them
• What are the 4 types of transportation

  Traction

  Saltation

  Suspension

  Solution
• Traction

  heavy rocks and boulders are rolled along the river bed because they are to big for the water to pick up
• Saltation

  Small pebbles and stones are 'bounced' along the river bed
• Suspension

  very small particles of sand or clay are easy to pick up so are 'suspended' in the water
• Solution

  when material is dissolved in the water it is carried by the river
• The 3 parts of a river

  Upper course

  Middle course

  Lower course
• Upper course landforms


  Waterfalls

  Gorges

  V-shaped valleys

  Interlocking spurs
• Middle course landforms


  Meanders and oxbow lakes
• Lower course landforms


  estuaries, floodplains and levees
• What is the profile of a river like at the top of the river

  The average velocity and discharge of a river increases along its course. Although the upper course has a steep gradient and is V shaped, the velocity depends on how much water comes into contact with the channel banks and bed.

  In the upper course the channel is shallow due to vertical erosion and narrow, so there is less friction. This is because in the upper course the rock is harder and so the valley sides are not widened out much by weathering and erosion. Therefore velocity is low
• What is the profile of a river like in the middle of a river

  In the middle course the river is flowing through lower country. The gradient is less steep, so the river begins to meander and erode laterally into the valley sides. The rate of erosion increases as the rocks that make up the valley sides. The rate of erosion increases as the rocks that make up the valley sides are softer. As the river uses more energy in lateral erosion it isn't able to remove all the eroded material so this builds up the valley floor to give it a more gentle profile
• What is the profile of a river like at the bottom of a river

  The lower course of a river flows through low lying land and has a wide an deep channel. Therefore, there is much friction resulting in a high velocity. The speed is boosted by the additional discharge from all tributaries. Deposition from floods builds up the flood plain and meanders migrate. This builds up and widens the river
• How are V-shaped valleys formed?

  Rivers begin high up in the mountains and erode the landscape vertically by cutting a deep notch using hydraulic action and abrasion. Freeze-thaw weathering loosens rocks on the valley sides, which fall into the river, aiding in corrasion and further erosion.
• What causes the steepening of valley sides in V-shaped valleys?

  Freeze-thaw weathering exposes the valley sides to erosion, loosening rocks that fall into the river, aiding in corrasion and further erosion.
• Interlocking spurs


  A series of ridges projecting out on alternate sides of a valley and around which a river winds its course.