As the saying goes ... "water, water, everywhere." Well, how much water is there; where is the water; how does it move around?
How Much Water?
The amount of water on Earth remains about the same from one year to the next, at about 70% of the earth’s surface. However, most of the water on Earth is not available for human use.
Of global water sources, 97.47% is saltwater and 2.53% is freshwater. Of the freshwater portion, most is found in ice (69.56%), while the remaining portions are found as deep groundwater (30.06%), or in surface waters (rivers, lakes and shallow groundwater) (0.389%). This means the available freshwater (not frozen or underground) is 0.01% of the total water on the planet.
Where is the Water?
Canada ranks fourth worldwide as having the most freshwater behind Russia, China and Brazil. Almost 9% of Canada's total area is covered by freshwater. Canada has more lake area than any other country in the world with an estimated 2 million lakes, covering approximately 7.6% of our land area.
The Great Lakes, Canada’s most important freshwater source, are the largest system of fresh, surface water on earth, containing roughly 20% of the world’s freshwater supply (Environment Canada 1995). Despite its large size, the Great Lakes Basin does not represent an inexhaustible supply of freshwater. The Great Lakes have roughly only 1% of its waters renewed each year by snowmelt and rain. This renewable volume is what is left each year for human use, which needs to be used in a sustainable manner, in order to protect water availability for future generations.