Water01 - ENVST110 Water Part 1 Page 1 of 15 Water:...

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ENVST110 Water Part 1 Page 1 of 15 Water : Although the majority of the planet’s surface is covered by water, this water is not suitable for most organisms on land. These terrestrial systems are dependent upon the tiny fraction of water that moves through the hydrologic cycle and comes down as rain or snow, entering rivers and lakes. Humans have also tapped into stored groundwater and are now increasingly looking to desalinate sea water to supply fresh water. http://ga.water.usgs.gov/edu/watercyclefreshstorage.html One estimate of global water distribution: Volume (1000 km 3 ) Percent of Total Water Percent of Fresh Water 1,338,000 96.5 - 24,064 1.74 68.7 Groundwater 23,400 1.7 - Fresh (10,530) (0.76) 30.1 Saline (12,870) (0.94) - Soil Moisture 16.5 0.001 0.05 300 0.022 0.86 Lakes 176.4 0.013 - Fresh (91.0) (0.007) .26 Saline (85.4) (0.006) - Atmosphere 12.9 0.001 0.04
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ENVST110 Water Part 1 Page 2 of 15 Swamp Water 11.47 0.0008 0.03 Rivers 2.12 0.0002 0.006 Biological Water 1.12 0.0001 0.003 Total 1,385,984 100.0 100.0 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. http://earthobservatory.nasa.gov/Library/Water/water.html As a society we have poorly managed our freshwater supplies. Evidence of this includes the fact that 1. Large rivers like the Colorado, Indus, Nile, and Yellow discharge little or no water to the sea for extended periods due to diversions. 2. The volume of the Oglala aquifer is down 10% (a volume equal to 18 yrs of flow from the Colorado) 3. The Aral Sea (4th largest body of freshwater) could disappear due to diversions primarily for cotton. The Department of the Interior recognized this threat to our livelihood when it issued the following statement: “The American West is facing a serious crisis. In the long run, we will not have enough water to meet the fast-growing needs of city residents, farmers, ranchers, Native Americans, and wildlife. The demand is increasing; the supply is not. It is time for Americans to become proactive in our efforts to resolve the problem. Crisis management is not a long-term solution.”- Department of the Interior http://www.doi.gov/initiatives/water2025.html Hydrologic cycle
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ENVST110 Water Part 1 Page 3 of 15 The hydrologic cycle provides the necessary freshwater for life on land. It is entirely solar driven, evaporating water from oceans, surface fresh water (rivers, lakes, etc.), vegetation, and soil. This water gas moves into the atmosphere and condenses to form clouds. The process of evaporation leaves behind impurities like salt and creates a rather pure form of water. This is one of the system’s purification steps. Some of these clouds then move over land and when the level of atmospheric
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Water01 - ENVST110 Water Part 1 Page 1 of 15 Water:...

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