Water Education - Water Quality

EARTH'S WATER DISTRIBUTION

Where is Earth's water located and in what forms does it exist? You can see how water is distributed by viewing these bar charts. The left-side bar shows where the water on Earth exists; about 97 percent of all water is in the oceans. The middle bar shows the distribution of that three percent of all Earth's water that is freshwater. The majority, about 69 percent, is locked up in glaciers and icecaps, mainly in Greenland and Antarctica. You might be surprised that of the remaining freshwater, almost all of it is below your feet, as ground watWorld Water Map er. No matter where on Earth you are standing, chances are that, at some depth, the ground below you is saturated with water. Of all the freshwater on Earth, only about 0.3 percent is contained in rivers and lakes—yet rivers and lakes are not only the water we are most familiar with, it is also where most of the water we use in our everyday lives exists.

For a detailed explanation of where Earth's water is, look at the data table below. Notice how of the world's total water supply of about 326 million cubic miles of water, over 96 percent is saline. And, of the total freshwater, over 68 percent is locked up in ice and glaciers. Another 30 percent of freshwater is in the ground. Surface-water sources, such as rivers, only constitute about 300 cubic miles (about 1/10,000 th of one percent of total water).

One estimate of global water distribution:
     
Water sourceWater volume, in cubic milesWater volume, in cubic kilometersPercent of fresh waterPercent of total water
Oceans, Seas, Bays321,000,0001,338,000,000--96.5
Ice caps, Glaciers; Permanent Snow5,773,00024,064,00068.71.74
Groundwater5,614,00023,400,000--1.7
Fresh2,526,00010,530,00030.10.76
Saline3,088,00012,870,000--0.94
Soil Moisture3,95916,5000.050.001
Ground Ice; Permafrost71,970300,0000.860.022
Lakes42,320176,400--0.013
Fresh21,83091,0000.26<0.007
Saline20,49085,400--0.006
Atmosphere3,09512,9000.040.001
Swamp Water2,75211,4700.030.0008
Rivers5092,1200.0060.0002
Biological Water2691,1200.0030.0001
>Total332,500,0001,386,000,000--100
Source: Gleick, P. H., 1996: Water resources. In Encyclopedia of Climate and Weather, ed. by S. H. Schneider, Oxford University Press, New York, vol. 2, pp.817-823.
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