River Hazards & Opportunities (CIE IGCSE Geography)

• The main river hazards are flooding and erosion
• Rivers flood when the water in them reaches bankfull discharge and then overspills across the floodplain
• Flooding occurs as the result of two main causes;
  • If there is a period of heavy, torrential rain leading to high levels of overland flow because the water cannot infiltrate 
  • A prolonged period of steady rain which means that the ground becomes saturated leading to high levels of overland flow because the water cannot infiltrate
• There are other natural causes of river flooding which include;
  • Landslides
  • Snow and ice melt
  • Storm surges pushing water up the river channel
• Although the root cause of flooding is precipitation the risk of flooding can be increased by human activities such as;
  • Urbanisation
  • Deforestation
  • Building of bridges and dams
  • Human induced climate change
  • Agriculture
• Flooding often goes hand in hand with erosion of the banks due to increased discharge and velocity

Hazards of flooding and erosion

• Flood waters may increase the spread of water related diseases;
  • The water may act as a breeding ground for the animals that spread disease for example, the mosquito 
  • The water may be contaminated by bacteria which can spread diseases such as cholera
• Deaths and injuries as floodplains are often densely populated due to the fertile soils
• Bridges and transport routes may be damaged or destroyed by the flood waters
• Erosion of the river banks leads to the loss of farmland, housing and transport routes
• Destruction of crops 
• Increased insurance costs 
• Lower house prices

Opportunities

• As well as the hazards there are many opportunities provided by rivers:
  • The silt deposited during flooding is often rich in minerals and nutrients, making it ideal for growing crops
  • Rivers are a source of food 
  • The floodplains are flat land which makes the construction and building of transport networks easier
  • Water can be used to irrigate farmland
  • Leisure and tourism
  • Generating electricity
  • Transporting goods and people