Geography Lesson2

• What is a drainage basin?

  area of land drained by a river and its tributaries , also called as “river catchment”
• what is a watershed?

  edge of highland surrounding a drainage basin which marks the boundary between two drainage basins
• what is a tributary?

  a smaller river or stream
• where does the water start flowing at a drainage basin?

  it starts at the highland/upland area
• what is a confluence/confluence point

  the point where two rivers meet
• how will the water eventually leave the river basin?

  through its mouth into the sea or a lake in a lowland area
• what is abrasion/corrosion?

  when boulders or stones wear away the river banks and bed
• what is hydraulic action?

  when sediment particles knock against the bed or each other and break, becoming more rounded and smaller as you move down the river
• what is attrition?

  force of fast flowing water hits the bed and banks and forces the water and air into cracks in the bedrock. The repeated changes in air pressure cause the river bed to weaken
• what is solution/corrosion (geography)?

  when acidic water dissolved rocks suck as chalk or limestone
• what is vertical erosion?

  downwards erosion which makes the riverbed deeper
• what is lateral erosion?

  side to side erosion , makes the channel more wider
• what are the stages in fluvial processes?

  Traction, saltation, suspension, solution
• what is traction

  rolling or dragging of large grains along river bed or shore aided by the push of smaller grains
• what is saltation

  small rocks or pebbles which are too big to be carried within water are transported and bounce along the bottom of the river bed
• what is suspension?

  lighter sediment is suspended (carried) within water most commonly near the mouth
• what is solution?

  dissolving of rocks such as chalk or limestone
• what is deposition?


  when material transported by a river is dropped