River landforms

• A river basin is the area of land surrounding a river, where any rain falling on the land eventually makes it way into that river

  A tributary is a small river that joins a main river

  The source is where the river starts, and the mouth is where it ends

  
• a river has an upper corse, a middle course, and a lower course
• rivers form channels and valleys as they flow downhill; they erode the landscape and wear it down
• V-Shaped valleys are formed by vertical erosion in the upper course
• V shape valley formation

  1. fast flowing water causes loose rough particles and boulders to be transported by the river and scraped along the river bed
  2. causes downward erosion of the river channel
  3. river doesn’t have enough energy to erode sideways, deepening the vertical erosion
  4. creates steep sided V shape
• Waterfall formation

  1. Form where a river flows over an area of hard rock followed by an area of softer rock
  2. Softer rock is eroded more than hard rock, creating a ‘step’
  3. Steep drop is eventually created, which is a waterfall
  4. The hard rock is undercut by erosion, and it becomes unsupported and collapses
  5. Collapsed rock erodes softer rock below
  6. overtime, the waterfall retreats, leaving behind a steep sided gorge

  
• meanders are large bends in rivers in the middle and lower courses
• meander formation

  1. Water takes the most energy efficient way when flowing downhill, causing it to slightly curve
  2. Current is faster on the outside of the bend as it is deeper there
  3. More erosion takes place on the outside of the bend, forming river cliffs
  4. Current is slower on the inside, deposition occurs
  5. Slip off slopes in the inside
• Oxbow lakes are formed from meanders
• Oxbow lake formation

  1. Erosion causes river meanders to get bendier and makes the neck narrow
  2. During floods the river takes the shortest course through the neck
  3. Deposition eventually cuts off the meander
  4. Leaves an oxbow lake

  
• Floodplains are the flat areas of land around a river that flood
• floodplains

  it is the wide valley floor on either side of a river

  • when a river floods onto the floodplain, the water slows down and deposits the eroded material on the floodplain
  • this builds it up, making it higher
  • they are found in the lower course
• Levees are natural embankments (raised bits) along the edges of a river channel

  • during a flood, eroded material is deposited over the whole floodplain
  • The heaviest material is deposited first, meaning it is deposited closest to the river channel
  • This builds up, creating levees along the edges of the channel