River Pollution Case Study: Nairobi River (Cambridge (CIE) IGCSE Geography) : Revision Note

Causes of pollution in the Nairobi River

Background

• The Nairobi River is 390 km long

• Its source is in the Ondiri swamp to the west of Nairobi

• Flowing through Nairobi, the capital city of Kenya

• Over 50% of the state's population lives on the banks of the river

• Much of the pollution in the river comes from the informal settlements which do not have a sewage or sanitation system

• The city does not have an effective waste management system

• The river contains various types of pollutants, including:

  • plastics

  • human effluent (sewage)

  • petrochemicals

  • heavy metals

  • disinfectants

  • detergents

Solid waste

• It is estimated that 2475 tonnes of waste is produced in the city every day

  • Much of this is disposed of in the river

khyk54, CC BY 2.0, via Wikimedia Commons

Industrial waste

• Many industries dispose of waste directly into the river; these include heavy metals and toxins

• Mining waste is washed into the river and its tributaries by rain

Agricultural waste

• Pesticides and fertilisers used on agricultural land are washed into the river

Impacts of pollution in the Nairobi River

• The Nairobi River is the only source of water for many people living in Nairobi

• It is used for cleaning, bathing, washing and watering

• People are consuming the river water, which leads to a range of health issues

  • Bacteria from sewage can lead to diseases such as typhoid, cholera and dysentery

  • Heavy metals and toxins lead to an increase in rates of cancer, damage to human and animal nervous systems and birth defects

• The polluted water is used to irrigate the market gardens, which also increases the risk of diseases

• Fertilisers have increased eutrophication and the growth of water hyacinth

  • Water hyacinth grows very rapidly and can clog the waterways and harm both plant and animal life in the river

  • The oxygen levels in the water are reduced

• The water has a foul smell and bubbles due to the presence of methane gas and hydrogen sulphide

• Aquatic life and habitats are destroyed and damaged by the presence of pollutants in the water

Strategies to manage pollution in the Nairobi River

• Past efforts to clean the Nairobi River have failed due to a lack of:

  • funding

  • education regarding the impacts of polluting the water

  • enforcement

  • data regarding the levels of pollution

  • effective waste management

• There is also corruption within local and national government

• In February 2023, the Nairobi Rivers Commission was launched

• The commission will:

  • Employ over 12,000 people to clean the river and plant trees

  • Introduce a plastic tax to help reduce plastic pollution

  • Involve and educate local people so they have an understanding of the impact their waste has on the river

• There is also work underway to improve the city's sewerage system