How Many Litres Of Water On Earth

Overview of the distribution of water on planet Earth

A graphical distribution of the locations of water on World

Nigh water in Globe'due south atmosphere and crust comes from saline seawater, while fresh water accounts for nearly 1% of the total. The vast bulk of the water on Globe is saline or table salt h2o, with an average salinity of 35‰ (or iii.5%, roughly equivalent to 34 grams of salts in i kg of seawater), though this varies slightly according to the amount of runoff received from surrounding land. In all, water from oceans and marginal seas, saline groundwater and water from saline closed lakes amount to over 97% of the water on Earth, though no airtight lake stores a globally significant corporeality of water. Saline groundwater is seldom considered except when evaluating water quality in arid regions.

The remainder of Earth's h2o constitutes the planet'due south fresh water resource. Typically, fresh h2o is defined every bit water with a salinity of less than one percent that of the oceans - i.east. below around 0.35‰. Water with a salinity betwixt this level and 1‰ is typically referred to as marginal water because information technology is marginal for many uses by humans and animals. The ratio of salt water to fresh water on Earth is effectually 50 to i.

The planet's fresh water is also very unevenly distributed. Although in warm periods such as the Mesozoic and Paleogene when there were no glaciers anywhere on the planet all fresh water was institute in rivers and streams, today most fresh water exists in the class of ice, snow, groundwater and soil moisture, with only 0.3% in liquid form on the surface. Of the liquid surface fresh h2o, 87% is independent in lakes, 11% in swamps, and just 2% in rivers. Small quantities of h2o besides exist in the atmosphere and in living beings.

Although the full volume of groundwater is known to be much greater than that of river runoff, a large proportion of this groundwater is saline and should therefore be classified with the saline water above. There is also a lot of fossil groundwater in arid regions that has never been renewed for thousands of years; this must non be seen as renewable water.

Distribution of saline and fresh water [edit]

The total volume of water on World is estimated at 1.386 billion km³ (333 million cubic miles), with 97.5% being salt h2o and two.5% beingness fresh water. Of the fresh water, simply 0.3% is in liquid form on the surface.^[ii] ^[3] ^[iv]

Considering the oceans that cover roughly 71% of the area of Earth reflect blue light, Earth appears blue from infinite, and is often referred to as the blue planet and the Stake Bluish Dot. Liquid freshwater like lakes and rivers cover about 1% of Globe's surface^[5] and altogether with Earth's ice cover, Globe'due south surface is 75% water by area.^[half-dozen]

Source of water	Volume of water in km³ (cu mi)	% full water	% table salt h2o	% fresh h2o	% liquid surface fresh h2o
Oceans	1,338,000,000 (321,000,000)	96.5	99.0
Pacific Ocean	669,880,000 (160,710,000)	48.3	49.6
Atlantic Body of water	310,410,900 (74,471,500)	22.4	23.0
Indian Ocean	264,000,000 (63,000,000)	19.0	19.5
Antarctic ocean	71,800,000 (17,200,000)	5.18	v.31
Arctic Bounding main	18,750,000 (4,500,000)	one.35	1.39
Ice and snow	24,364,000 (5,845,000)	ane.76		69.6
Glaciers	24,064,000 (5,773,000)	1.74		68.seven
Antarctic ice sheet	21,600,000 (5,200,000)	1.56		61.7
Greenland ice sheet	2,340,000 (560,000)	0.17		vi.68
Arctic islands	83,500 (twenty,000)	0.006		0.24
Mountain ranges	40,600 (nine,700)	0.003		0.12
Ground ice and permafrost	300,000 (72,000)	0.022		0.86
Groundwater	23,400,000 (5,600,000)	1.69
Saline groundwater	12,870,000 (3,090,000)	0.93	0.95
Fresh groundwater	x,530,000 (2,530,000)	0.76		30.one
Soil moisture	16,500 (4,000)	0.0012		0.047
Lakes	176,400 (42,300)	0.013
Saline lakes	85,400 (xx,500)	0.0062	0.0063
Caspian Ocean	78,200 (xviii,800)	0.0056	0.0058
Other saline lakes	7,200 (1,700)	0.00052	0.00053
Fresh h2o lakes	91,000 (22,000)	0.0066		0.26	87.0
African Great Lakes	thirty,070 (7,210)	0.0022		0.086	28.8
Lake Baikal	23,615 (5,666)	0.0017		0.067	22.6
North American Dandy Lakes	22,115 (five,306)	0.0016		0.063	21.1
Other fresh water lakes	15,200 (three,600)	0.0011		0.043	14.5
Atmosphere	12,900 (iii,100)	0.00093		0.037
Swamps	xi,470 (2,750)	0.00083		0.033	11.0
Rivers	ii,120 (510)	0.00015		0.0061	2.03
Biological h2o	one,120 (270)	0.000081		0.0032

"Logarithm" Graph of Source of Water in Cubic Miles

Fresh Water Source (including saline lakes and saline groundwater)

Lakes [edit]

Collectively, World'southward lakes hold 199,000 kmⁱⁱⁱ of water.^[7] Virtually lakes are in the loftier northern latitudes, far from man population centers.^[8] ^[9] The North American Great Lakes, which incorporate 21% of the world'southward fresh water by book,^[ten] ^[11] ^[12] are an exception. The Great Lakes Basin is dwelling to 33 meg people.^[xiii] The Canadian cities of Thunder Bay, St. Catharines, Hamilton, Toronto, Oshawa, and Kingston, as well every bit the U.S. cities of Duluth, Milwaukee, Chicago, Gary, Cleveland, Buffalo, and Rochester are all located on shores of the Neat Lakes.

Groundwater [edit]

Fresh groundwater is of keen value, peculiarly in arid countries such equally China. Its distribution is broadly like to that of surface river water, but information technology is easier to store in hot and dry climates considering groundwater storage are much more shielded from evaporation than are dams. In countries such as Republic of yemen, groundwater from erratic rainfall during the rainy season is the major source of irrigation water.

Considering groundwater recharge is much more than difficult to accurately measure than surface runoff, groundwater is not generally used in areas where even fairly limited levels of surface h2o are available. Even today, estimates of total groundwater recharge vary greatly for the same region depending on what source is used, and cases where fossil groundwater is exploited across the recharge rate (including the Ogallala Aquifer^[xiv]) are very frequent and virtually always non seriously considered when they were first developed.

Distribution of river water [edit]

The total book of water in rivers is estimated at 2,120 km³ (510 cubic miles), or 0.49% of the surface fresh water on World.^[2] Rivers and basins are frequently compared not according to their static volume, just to their flow of water, or surface run off. The distribution of river runoff across the Earth's surface is very uneven.

Continent or region	River runoff (km³/year)	Percentage of globe total
Asia (excluding Middle Eastward)	13,300	30.6
South America	12,000	27.6
North America	7,800	17.9
Oceania	6,500	fourteen.9
Sub-Saharan Africa	4,000	nine.2
Europe	2,900	6.7
Commonwealth of australia	440	1.0
Middle East and Northward Africa	140	0.3

There tin can be huge variations within these regions. For example, as much as a quarter of Australia's limited renewable fresh water supply is found in almost uninhabited Greatcoat York Peninsula.^[15] Too, even in well-watered continents, there are areas that are extremely curt of water, such equally Texas in North America, whose renewable water supply totals merely 26 km³/year in an surface area of 695,622 kmⁱⁱ, or South Africa, with just 44 km³/year in 1,221,037 km².^[15] The areas of greatest concentration of renewable h2o are:

The Amazon and Orinoco Basins (a total of half dozen,500 km³/year or fifteen percentage of global runoff)
East Asia
- Yangtze Bowl - i,000 km³/year
South and Southeast Asia, with a total of 8,000 km³/year or 18 percent of global runoff
- Ganges Basin - 900 km³/year
- Irrawaddy Bowl - 500 km³/year
- Mekong Basin - 450 km³/twelvemonth
Canada, with over 10 percentage of world'southward river h2o and large numbers in lakes
- Mackenzie River - over 250 km³/year
- Yukon River - over 150 km³/year
Siberia
- Yenisey - over v% of earth's fresh h2o in basin - 2d largest subsequently the Amazon
- Ob River - over 500 km³/yr
- Lena River - over 450 km³/year
New Republic of guinea
- Wing and Sepik Rivers - full over 300 km³/year in only about 150,000 km² of bowl area.

Area, book, and depth of oceans [edit]

Body of Water	Area (10^vi km²)	Volume (x^six km^three)	Hateful Depth (m)
Pacific Ocean	165.2	707.half dozen	4,282
Atlantic Bounding main	82.iv	323.6	three,926
Indian Ocean	73.4	291.0	three,963
All oceans and seas	361	1,370	3,796

The oceanic crust is immature, thin and dense, with none of the rocks within it dating from whatever older than the breakdown of Pangaea.^{[ citation needed ]} Because water is much denser than whatsoever gas, this means that h2o will menses into the "depressions" formed equally a result of the high density of oceanic chaff (on a planet like Venus, with no water, the depressions announced to class a vast plain above which rising plateaux). Since the low density rocks of the continental crust contain large quantities of hands eroded salts of the brine and alkaline metal earth metals, salt has, over billions of years, accumulated in the oceans as a result of evaporation returning the fresh water to land as rain and snow.^{[ commendation needed ]}

Variability of water availability [edit]

Variability of water availability is important both for the functioning of aquatic species and also for the availability of water for human utilize: h2o that is but available in a few wet years must non be considered renewable. Because most global runoff comes from areas of very depression climatic variability, the total global runoff is more often than not of low variability.

Indeed, fifty-fifty in most arid zones, in that location tends to be few problems with variability of runoff because nearly usable sources of h2o come from high mountain regions which provide highly reliable glacier melt every bit the primary source of water, which also comes in the summer peak period of high need for water. This historically aided the development of many of the peachy civilizations of ancient history, and even today allows for agriculture in such productive areas equally the San Joaquin Valley.

Nonetheless, in Australia and Southern Africa, the story is different. Here, runoff variability is much higher than in other continental regions of the world with similar climates.^[16] Typically temperate (Köppen climate classification C) and arid (Köppen climate nomenclature B) climate rivers in Australia and Southern Africa have as much every bit three times the coefficient of variation of runoff of those in other continental regions.^[17] The reason for this is that, whereas all other continents take had their soils largely shaped by Quaternary glaciation and mountain building, soils of Australia and Southern Africa accept been largely unaltered since at to the lowest degree the early Cretaceous and by and large since the previous ice age in the Carboniferous. Consequently, bachelor nutrient levels in Australian and Southern African soils tend to be orders of magnitude lower than those of like climates in other continents, and native flora compensate for this through much higher rooting densities (e.g. proteoid roots) to absorb minimal phosphorus and other nutrients. Considering these roots absorb and so much h2o, runoff in typical Australian and Southern African rivers does non occur until virtually 300 mm (12 inches) or more of rainfall has occurred. In other continents, runoff will occur after quite light rainfall due to the low rooting densities.

Climate blazon (Köppen^[eighteen])	Mean annual rainfall	Typical runoff ratio for Commonwealth of australia and Southern Africa	Typical runoff ratio for balance of the world
BWh	250 mm (10 inches)	1 per centum (2.5 mm)	x pct (25 mm)
BSh (on Mediterranean fringe)	350 mm (14 inches)	3 percent (12 mm)	20 percent (80 mm)
Csa	500 mm (20 inches)	5 percent (25 mm)	35 percent (175 mm)
Caf	900 mm (36 inches)	15 percent (150 mm)	45 percent (400 mm)
Cb	1100 mm (43 inches)	25 percent (275 mm)	lxx percent (770 mm)

The consequence of this is that many rivers in Australia and Southern Africa (every bit compared to extremely few in other continents) are theoretically impossible to regulate because rates of evaporation from dams hateful a storage sufficiently big to theoretically regulate the river to a given level would actually allow very little draft to be used. Examples of such rivers include those in the Lake Eyre Bowl. Even for other Australian rivers, a storage iii times every bit large is needed to provide a third the supply of a comparable climate in southeastern North America or southern China. Information technology likewise affects aquatic life, favouring strongly those species able to reproduce rapidly afterwards high floods so that some will survive the side by side drought.

Tropical (Köppen climate nomenclature A) climate rivers in Australia and Southern Africa practise not, in dissimilarity, have markedly lower runoff ratios than those of similar climates in other regions of the world. Although soils in tropical Australia and southern Africa are even poorer than those of the barren and temperate parts of these continents, vegetation can utilise organic phosphorus or phosphate dissolved in rainwater as a source of the nutrient. In cooler and drier climates these ii related sources tend to be about useless, which is why such specialized ways are needed to extract the virtually minimal phosphorus.

There are other isolated areas of high runoff variability, though these are basically due to erratic rainfall rather than different hydrology. These include:^[17]

Western asia
The Brazilian Nordeste
The Great Plains of the United States

Possible h2o reservoirs inside Earth [edit]

It has been hypothesized that the water is present in the Globe's crust, drape and even the cadre and interacts with the surface ocean through the "whole-Earth water wheel". However, the actual amount of water stored in the Earth's interior all the same remains under debate. An estimated 1.five to xi times the amount of water in the oceans may be constitute hundreds of kilometers deep within the Earth's interior, although not in liquid course.^{[ commendation needed ]}

Water in Earth'due south drape [edit]

Ringwoodite is the major stage at the Earth's mantle betwixt ~520 and ~660 km depth, possibly containing several weight percentage of water in its crystal structure.

The lower drapery of inner globe may concord every bit much as 5 times more water than all surface water combined (all oceans, all lakes, all rivers).^[19]

The amount of h2o stored in the Earth's interior may equal or exceed that in all of the surface oceans.^[twenty] Some researchers proposed the total mantle h2o budget may amount to tens of ocean masses.^[21] The water in the World's pall is primarily dissolved in nominally anhydrous minerals as hydroxyls (OH).^[22] These OH impurities in rocks and minerals tin can lubricates tectonic plate, influence rock viscosity and melting processes, and slow downwardly seismic waves.^[20] The two drapery phases at the transition zone between World's upper and lower mantle, wadsleyite and ringwoodite, could potentially incorporate upwards to a few weight percent of h2o into their crystal structure.^[23] Direct testify of the presence of h2o in the Globe'south drapery was found in 2014 based on a hydrous ringwoodite sample included in a diamond from Juína, Brazil.^[24] Seismic observations advise the presence of water in aridity melt at the tiptop of the lower drapery under the continental US.^[25] Molecular h2o (H_iiO) is non the primary h2o-bearing phase(s) in the mantle, only its high-pressure class, ice-Vii, as well has been plant in super-deep diamonds.

Run into also [edit]

Deficit irrigation
Water resource management
Magmatic water
Origin of water on Earth

References [edit]

^ USGS - Earth'southward water distribution
^ ^a ^b Where is Earth's water?, United states of america Geological Survey.
^ Eakins, B.West. and G.F. Sharman, Volumes of the World's Oceans from ETOPO1, NOAA National Geophysical Data Center, Boulder, CO, 2010.
^ Water in Crisis: Chapter 2, Peter H. Gleick, Oxford Academy Press, 1993.
^ Downing, J. A.; Prairie, Y. T.; Cole, J. J.; Duarte, C. M.; Tranvik, 50. J.; Striegl, R. G.; McDowell, W. H.; Kortelainen, P.; Caraco, N. F.; Melack, J. M.; Middelburg, J. J. (2006). "The global affluence and size distribution of lakes, ponds, and impoundments". Limnology and Oceanography. Wiley. 51 (5): 2388–2397. doi:10.4319/lo.2006.51.five.2388. ISSN 0024-3590. S2CID 10011358.
^ "Globe Observatory Water Cycle Overview". Atmospheric precipitation Education. 2010-09-02. Retrieved 2022-01-xvi .
^ Cael, B. B.; Heathcote, A. J.; Seekell, D. A. (2017). "The volume and mean depth of Earth's lakes". Geophysical Research Letters. 44 (i): 209–218. doi:ten.1002/2016GL071378. hdl:1912/8822. ISSN 1944-8007. S2CID 132520745.
^ Verpoorter, Charles; Kutser, Tiit; Seekell, David A.; Tranvik, Lars J. (2014). "A global inventory of lakes based on loftier-resolution satellite imagery". Geophysical Research Messages. 41 (18): 6396–6402. doi:10.1002/2014GL060641. ISSN 1944-8007. S2CID 129573857.
^ Kummu, Matti; Varis, Olli (2011-04-01). "The earth by latitudes: A global analysis of human population, evolution level and environs across the due north–south axis over the past one-half century". Practical Geography. 31 (2): 495–507. doi:10.1016/j.apgeog.2010.10.009. ISSN 0143-6228.
^ "Great Lakes – U.S. EPA". Epa.gov. 2006-06-28. Retrieved 2011-02-nineteen .
^ "LUHNA Chapter six: Historical Landcover Changes in the Great Lakes Region". Biological science.usgs.gov. 2003-eleven-twenty. Archived from the original on 2012-01-xi. Retrieved 2011-02-19 .
^ Ghassemi, Fereidoun (2007). Inter-basin water transfer. Cambridge, Cambridge University Printing. ISBN978-0-521-86969-0.
^ "Archived copy". Archived from the original on 2015-11-01. Retrieved 2015-10-29 . {{cite web}}: CS1 maint: archived copy every bit title (link)
^ Reisner, Marc; Cadillac Desert: The American Westward and its Disappearing H2o; pp. 438-442. ISBN 0-fourteen-017824-4
^ ^a ^b Brown, J. A. H.; Commonwealth of australia's surface water resources. ISBN 978-0-644-02617-8.
^ McMahon, T.A. and Finlayson, B.50.; Global Runoff: Continental Comparisons of Annual Flows and Height Discharges. ISBN 3-923381-27-1.
^ ^a ^b Skin, Murray C.; McMahon, Thomas A. & Finlayson, Brian L. (2004). "Continental differences in the variability of annual runoff: update and reassessment". Journal of Hydrology. 295 (1–four): 185–197. Bibcode:2004JHyd..295..185P. doi:10.1016/j.jhydrol.2004.03.004.
^ This section uses a slightly modified version of the Köppen system institute in The Times Atlas of the World, 7th edition. ISBN 0-7230-0265-7
^ Harder, Ben. "Inner World May Hold More than H2o Than the Seas". National Geographic . Retrieved fourteen November 2013.
^ ^a ^b Hirschmann, Marc; Kohlstedt, David (2012-03-01). "Water in World's curtain". Physics Today. 65 (three): 40. doi:10.1063/PT.3.1476. ISSN 0031-9228.
^ Ohtani, Eiji (2020-12-18). "Hydration and Dehydration in Earth's Interior". Almanac Review of Earth and Planetary Sciences. 49: 253–278. doi:ten.1146/annurev-earth-080320-062509. ISSN 0084-6597. S2CID 232569436.
^ Bong, David R.; Rossman, George R. (1992). "Water in Earth'south Pall: The Role of Nominally Anhydrous Minerals". Science. 255 (5050): 1391–1397. doi:10.1126/science.255.5050.1391. PMID 17801227. S2CID 26482929.
^ Kohlstedt, D. L.; Keppler, H.; Rubie, D. C. (1996-05-20). "Solubility of h2o in the α, β and γ phases of (Mg,Fe) two SiO four". Contributions to Mineralogy and Petrology. 123 (iv): 345–357. doi:x.1007/s004100050161. ISSN 0010-7999. S2CID 96574743.
^ Pearson, D. G.; Brenker, F. E.; Nestola, F.; McNeill, J.; Nasdala, L.; Hutchison, 1000. T.; Matveev, South.; Mather, K.; Silversmit, G.; Schmitz, S.; Vekemans, B. (March 2014). "Hydrous mantle transition zone indicated past ringwoodite included within diamond". Nature. 507 (7491): 221–224. doi:10.1038/nature13080. ISSN 0028-0836. PMID 24622201. S2CID 205237822.
^ Schmandt, B.; Jacobsen, South. D.; Becker, T. Westward.; Liu, Z.; Dueker, Yard. G. (2014-06-thirteen). "Aridity melting at the top of the lower mantle". Science. 344 (6189): 1265–1268. doi:10.1126/scientific discipline.1253358. ISSN 0036-8075. PMID 24926016. S2CID 206556921.