rivers

• Hydraulic Action: The motion of water hitting against the surface
• Abrasion: Scraping or wearing away
• Attrition: The impact of the rock grains hitting off one another
• Solution: Minerals are dissolved in the water and carried along
• The material carried by a river is called its load
• Rivers deposit their load when they slow down or lose energy.

  • When a river runs through a flatter gradient
  • At the mouth of a river
  • At the inside bend of a meander
• Features of Deposition:

  • Levee
  • Ox bow lake
  • Delta 
• Formation of a Waterfall 

  • When a river flows over an area of hard rock that lies over soft rock the soft rock erodes faster causing a vertical drop to form
  • A plunge pool is formed from the force of the moving water (hydraulic action) and the river’s load smashing  against the base (abrasion)
  • Sometimes an undercut is formed leaving rock hanging above that will eventually collapse into the plunge pool  
  • The process continues and the waterfall continues to retreat upstream.
• Social Impacts of Flooding: 

  Loss of lives and property. Immediate impacts of flooding include loss of human life, damage to property, destruction of crops, loss of livestock, non-functioning of infrastructure facilities and deterioration of health condition owing to waterborne diseases
• Settlement occurred near rivers in the past for the following reasons: 

  • Source of fresh drinking water
  • Source of food (fish)
  • Mode of transport back to coast
  • Bridging point
  • Recreational activities
  • Defence 
• Levees are found in the old stage of a river where the river is losing energy. A Levee is made up of alluvium on the banks of a river. Levees form during floods when the river banks burst and deposits its load either side of the river channel. Heavier material is deposited on the flood plain. After many floods mounds form on the river bank to form levees.