Science of Water

PDF version available here

Freshwater is a finite resource. Of all the water on Earth:

• 97% -Oceans
• 2.2% -Locked in Glaciers and Icecaps,which leaves
• 0.8%- Rivers, Lakes and Groundwater for everyday use

The Water Cycle:

The water cycle,or the hydrologic cycle, is the process of water moving through the earth. Water evaporates and transpires from the earth’s surface into the atmosphere as water vapor to form clouds and then precipitates back to the earth in the form of rain or snow in an endless cycle.

Global Distribution of Freshwater:

Differences in global temperature and precipitation patterns create diverse climate zones across the earth’s surface, which in turn results in a varied distribution of freshwater. Climate zones include: Tropical, Subtropical, Arid, Semiarid, Mediterranean Temperate, Oceanic, Continental, Alpine, Subarctic, Polar, and Antarctic.

Watersheds and Catchment Basins:

Watersheds, or catchment basins, are areas of land defined by the flow patterns of rainwater or melting snow and ice. In general terms, a watershed is a geographic area where all water, sediments, and dissolved materials drain to a common outlet, a stream, river system, reservoir, underground aquifer, or other body of water. A watershed can also be thought of as an area that "catches" water and routes it to a common basin, channel, or network of channels.

Part 1 of 6 Earth Day Network Water Fact Sheets