River Hazards & Opportunities (Cambridge (CIE) O Level Geography)

Causes of River Hazards

• 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