Water on earth is constantly moving. We can see it moving on the Earth, in rivers, lakes and oceans, but did you realize that it also moves above and below us? It also goes through different phases, sometimes it’s a liquid, other times it is a solid or a vapour. The amount of water on the Earth is fairly constant, although it can spend long periods of time “in storage”. the cycle is powered by solar energy. This global process consists of a large number of processes required to complete the cycle.

The many processes involved in the Earth’s water cycle.

Watch the following video by NASA Earth Sciences to learn more about the water cycle from a global perspective. What affect evaporation? Where  and how is water stored, and how is it moved around the Earth?  How do large storms affect temperatures?

The Human Effect On The Water Cycle

Humans are having an enormous and negative effect on the water cycle. Our activities are altering the water cycle by decreasing the amount available which will lead to water shortages.

   Through industrial and agricultural use we are adding pesticides, industrial pollutants, human waste and medical substances that effect the overall quality of the water.

   We are paving over large portions of land which leads to less water being absorbed and more runoff causing either floods or droughts.

   Dams are disturbing large sections of habitat and causing a build-up of silt while diverting water from areas below the dam.

   Deforestion severely disrupts the water cycle not only locally but also in surrounding areas since trees release water vapour which effects local humidity and then evaporates into the atmosphere to eventually be precipitated back to Earth.

These are just a few effects we have on the water cycle and places in the world are already facing the ramifications of human activity. More than one billion people do not have access to clean drinking water and more people die each year from unsafe water than all deaths caused by violence (including wars).

Sources:

Water Scarcity Map | Water Shortage in the World | Growing Blue™ Tool. (n.d.). Retrieved from http://growingblue.com/the-growing-blue-tool/

Water quality | International Decade for Action ‘Water for Life’ 2005-2015. (n.d.). Retrieved from http://www.un.org/waterforlifedecade/quality.shtml