|Glencoe Earth Science. New York: National Geographic Society, 2002: 240.||"Location: Lakes (Freshwater).Surface Area: 855, 000 km^2. Water Volume: 123,000 km3 Percentage of Total Water: 0.009 %"||123,000 km3|
|"Earth's Freshwater." Macmillan Encyclopedia of the Earth Sciences. New York: Simon & Schuster, 1996: 230.||
|Water Supply of the World. Infoplease Kid's Almanac. Original Source: United States Geological Survey: May 22, 2005.||
|Where is Earth's Water Located? USGS Water Science For Schools. Original Source: United States Geological Survey: May 22, 2005.||
|Debenedetti, Pablo G. & H. Eugene Stanley. "Supercooled and Glassy Water." Physics Today. (June 2003): 40.||"There are 1.3 × 109 km3 of water in oceans, 3.3 x10^7 km3in Polar ice Caps, 2 × 105 km3 in the glaciers, 105 km3 in lakes and 1.2 × 103 km3 in rivers"||100,000 km3|
Water is an odorless, normally colorless, transparent and tasteless liquid. Yet it takes up seventy-one percent of the Earth, giving Earth the name " the Water Planet". Water is also the reason why there is life on Earth and not on the other planets as of today. The human body is made up mostly of water and humans are instructed by doctors to drink eight cups of water in a single day. Is there really that much water and where does all this water for six billion people come from?
The truth is that there is not that much water available for human use. Less than one percent of the water on Earth is usable by humans. The usable water is in freshwater lakes and rivers. A lake is an inland body of standing water of great size usually fed by rivers and underground springs. Lakes may be formed by rivers being blocked, earthquakes, landslides, volcanic eruptions, glaciers and ice. People benefit from lakes. Lakes provide us with not only water but also food, jobs and many other things. Lakes are homes to thousands of aquatic species. Lakes are also great places for fish to live.
Lakes take up a volume of 125, 045 cubic kilometers and are 0.009% of the total water on earth. The total amount of water on Earth is is 1,360,000,000 cubic kilometers. However, the volume of Earth's lakes is constantly changing because of inflows and outflows. Inflows consist of precipitation and rainfall. Outflows consist of evaporation and discharge to ground water. The largest salt water lake in the world, by volume, is the Caspian Sea. The Great Lakes in the Northern United States are some of the greatest freshwater lakes in the world. Lake Superior ranks as the fourth largest lake in the world and the largest freshwater lake in the world.
Whatever the numbers may be, it is important that we use the limited supply of freshwater on earth wisely.
Hamida Daud -- 2005