Impact of human factors

• There are lots of ways in which people can disrupt the water and drainage basin cycles. For example:

  • Deforestation
  • (Over)abstraction
  • Creating reservoirs
  • Urbanisation
• Deforestation


  • The tropics - fragile natural environments
  • Removal of dense forest canopy protecting topsoil can have devastating consequences
  • E.g. for new roads, palm oil plantations, and agribusiness
  • Disrupts drainage basin cycle by accelerating natural processes
• Overabstraction


  Thames basin - 13m people

  • 690mm of rainfall a year
  • 40% of London's water comes from chalk aquifers
  • Abstracting too much water from groundwater reserves leads to rivers drying up in times of low rainfall
• Changing land use - urbanisation

  • Building new storage reservoirs, or abstracting more water from rivers and groundwater reserves helps to satisfy increasing water demands of expanding cities at the expense of natural water flows
  • Physical character of urban areas can also affect local hydrological cycle
• Reservoirs


  • Man-made storage reservoirs interrupt natural flows of water by delaying flows through a drainage basin and adding to the amounts lost through evaporation
  • Estimated 7% more water is evaporated from reservoirs than is actually used
• Cloud seeding


  The attempt to change the amount or type of precipitation by dispersing substances in the air that serve as cloud condensation nuclei.

  • E.g. Dubai, Beijing, California