Fresh water: Difference between revisions - Wikipedia

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== Water distribution ==

[[File:Earth water distribution.svg|thumb|upright=1.3|Visualisation of the distribution (by volume) of water on Earth.{{efn|Each tiny cube{{efn-lr|The entire block comprises 1 million tiny cubes.}} (such as the one representing biological water) corresponds to approximately 1400 cubic km of water, with a mass of approximately 1.4 trillion tonnes (235000 times that of the [[Great Pyramid of Giza]] or 8 times that of [[Lake Kariba]], arguably the heaviest man-made object).<ref>[http://ga.water.usgs.gov/edu/waterdistribution.html USGS – Earth's water distribution] {{webarchive|url=https://web.archive.org/web/20120629055146/http://ga.water.usgs.gov/edu/waterdistribution.html |date=29 June 2012 }}. Ga.water.usgs.gov (11 December 2012). Retrieved on 29 December 2012.</ref>}}]][[File:Earth's_water_distribution.svg|thumb|A graphical distribution of the locations of water on Earth. {{efn|Only 3% of the Earth's water is fresh water. Most of it is in icecaps and glaciers (69%) and groundwater (30%), while all lakes, rivers and swamps combined only account for a small fraction (0.3%) of the Earth's total freshwater reserves.{{citation needed}}}}]]

{{main|Water distribution on Earth}}

Saline water in [[ocean]]s, [[sea]]s and saline [[groundwater]] make up about 97% of all the water on [[Earth]]. Only 2.5–2.75% is fresh water, including 1.75–2% frozen in [[glacier]]s, [[ice]] and snow, 0.5–0.75% as fresh groundwater and [[soil]] moisture, and less than 0.01% of it as [[surface water]] in [[lake]]s, [[swamp]]s and [[river]]s.<ref>[http://ga.water.usgs.gov/edu/earthwherewater.html Where is Earth's water?] {{webarchive|url=https://web.archive.org/web/20131214091601/http://ga.water.usgs.gov/edu/earthwherewater.html |date=14 December 2013 }}, [[United States Geological Survey]].</ref><ref>[http://www.physicalgeography.net/fundamentals/8b.html Physicalgeography.net] {{webarchive|url=https://web.archive.org/web/20160126072955/http://www.physicalgeography.net/fundamentals/8b.html |date=26 January 2016 }}. Physicalgeography.net. Retrieved on 29 December 2012.</ref> Freshwater lakes contain about 87% of this fresh surface water, including 29% in the [[African Great Lakes]], 22% in [[Lake Baikal]] in Russia, 21% in the [[North American Great Lakes]], and 14% in other lakes. Swamps have most of the balance with only a small amount in rivers, most notably the [[Amazon River]]. The atmosphere contains 0.04% water.<ref>{{cite book |last= Gleick |first= Peter |author-link=Peter Gleick|editor= Stephen H. Schneider |title= Encyclopedia of Climate and Weather|url= https://archive.org/details/encyclopediaofcl02schn |url-access= registration |publisher= Oxford University Press |year= 1996|display-authors=etal}}</ref> In areas with no fresh water on the ground surface, fresh water derived from [[precipitation (meteorology)|precipitation]] may, because of its lower density, overlie saline ground water in lenses or layers. Most of the world's fresh water is frozen in [[ice sheet]]s. Many areas have very little fresh water, such as [[desert]]s.