The hydrological cycle. Image credit

ZIMSEC O Level Geography Notes:Natural Resources: Water: Hydrological cycle

  • If you are looking for the Hydrological Cycle explanation from Physical Geography please click/tap here.
  • The water cycle replenishes the world’s water resources through rain.
  • Hydro means water.
  • Rain water flows into streams and rivers as run-off sinks into the ground to form ground water.
  • Ground water is usually trapped in porous rocks which lie between impermeable rocks.
  • These underground water storing rock layer are referred to as aquifers.
  • The water from aquifers is made available to people by drilling wells and boreholes then pumping it out.
  • The water available for human consumption is also being replenished by the melting of ice caps and glaciers as the world’s climate becomes increasingly warmer.
  • Though water is a crucial resource for human survival, it is increasingly becoming limited resource in many countries, particularly the developing countries.
  • It is also noted that where supplies of fresh water are limited, the quality of the water available deteriorates and human health is compromised as the quality of life also deteriorates.
  • Where water supplies are below 1 000 m3 per person per year, the area is referred to as a water scarcity zone.
  • Areas with 1 000 m3 per person per year but less than 1 700 m3 per person per year of fresh water supplies are described as water stress zones.
  • Areas with more than 1 700 m3 of fresh water supplies per person per year are described as water abundance zones.
  • Most developing countries are experiencing a decline from water abundance situation to situations of acute scarcity due to increased consumption levels which are far above the natural water replenishing rates.
  • This is a result of expanding populations accompanied by frequent droughts and a general lack of resources resulting in obtaining water from great distances.
  • Most developing countries still have large percentages of their populations with no access to safe fresh water.
  • Almost all people in developing countries have access to safe water.
  • Developed countries which generally have 100% access to safe water and sanitation have infant mortality rates below 10 per 1 000 births.

To access more topics go to the O Level Geography Notes page