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{{Short description|Sources of water that are potentially useful}} |
{{Short description|Sources of water that are potentially useful}} |
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{{About|all types of waters that are of potential use to humans|a naturally occurring type of water resource that humans use a lot|fresh water}} |
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[[File:Global Values of Water Resources and Water Use.jpg|thumb|upright=1.8|Global values of water resources and human water use (excluding [[Antarctica]]). Water resources 1961-90, water use around 2000. Computed by the global freshwater model [[WaterGAP]].]] |
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'''Water resources '''are [[natural resource]]s of [[water]] that are potentially useful for humans,<ref>{{Cite web |title=water resource {{!}} Britannica |url=https://www.britannica.com/science/water-resource |access-date=2022-05-17 |website=www.britannica.com |language=en}}</ref> for example as a source of drinking [[water supply]] or [[irrigation]] water. 97% of the water on the Earth is [[Saline water|salt water]] and only three percent is [[fresh water]]; slightly over two-thirds of this is frozen in [[glacier]]s and [[Polar climate|polar]] [[ice cap]]s.<ref name="USGS dist">{{cite web|url=http://ga.water.usgs.gov/edu/waterdistribution.html|title=Earth's water distribution|publisher=United States Geological Survey|access-date=2009-05-13}}</ref> The remaining unfrozen freshwater is found mainly as groundwater, with only a small fraction present above ground or in the air.<ref>{{cite web | title=Scientific Facts on Water: State of the Resource| publisher=GreenFacts Website | access-date=2008-01-31 | url= http://www.greenfacts.org/en/water-resources/index.htm#2}}</ref> Natural sources of [[fresh water]] include [[surface water]], under river flow, [[groundwater]] and [[frozen water]]. Artificial sources of fresh water can include treated wastewater ([[Reclaimed water|wastewater reuse]]) and [[Desalination|desalinated seawater]]. Human uses of water resources include [[agricultural]], [[Industrial sector|industrial]], [[household]], [[recreational]] and [[natural environment|environmental]] activities. |
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'''Water resources''' are [[natural resource]]s of [[water]] that are potentially useful for humans,<ref>{{Cite web |title=water resource {{!}} Britannica |url=https://www.britannica.com/science/water-resource |access-date=2022-05-17 |website=www.britannica.com |language=en}}</ref> for example as a source of drinking [[water supply]] or [[irrigation]] water. 97% of the water on Earth is [[saline water|salt water]] and only three percent is [[fresh water]]; slightly over two-thirds of this is frozen in [[glacier]]s and [[polar climate|polar]] [[ice cap]]s.<ref name="USGS dist">{{cite web|url=http://ga.water.usgs.gov/edu/waterdistribution.html|title=Earth's water distribution|publisher=United States Geological Survey|access-date=2009-05-13}}</ref> The remaining unfrozen freshwater is found mainly as groundwater, with only a small fraction present above ground or in the air.<ref>{{cite web | title=Scientific Facts on Water: State of the Resource| publisher=GreenFacts Website | access-date=2008-01-31 | url= http://www.greenfacts.org/en/water-resources/index.htm#2}}</ref> Natural sources of [[fresh water]] include [[surface water]], under river flow, [[groundwater]] and [[ice|frozen water]]. Non-natural or ''human-made'' sources of fresh water can include [[Reclaimed water|wastewater that has been treated for reuse options]], and [[desalination|desalinated seawater]]. People use water resources for [[agriculture|agricultural]], [[Industry (economics)|industrial]] and [[household]] activities. |
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Water resources are under threat from [[water scarcity]], [[water pollution]], [[water conflict]] and [[climate change]]. Fresh water is a [[renewable resource]] |
Water resources are under threat from multiple issues. There is [[water scarcity]], [[water pollution]], [[water conflict]] and [[climate change]]. Fresh water is in principle a [[renewable resource|renewable resource.]] However, the world's supply of [[groundwater]] is steadily decreasing. Groundwater depletion (or [[overdrafting]]) is occurring for example in Asia, South America and North America. |
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{{TOC limit|3}} |
{{TOC limit|3}} |
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== Natural sources of fresh water == |
== Natural sources of fresh water == |
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{{Further|Water distribution on Earth}}{{Pie chart|thumb=right|caption='''Distribution of Freshwater Resources by Type'''<ref>{{Cite web |title=Strains on freshwater resources |url=https://datatopics.worldbank.org/sdgatlas/goal-6-clean-water-and-sanitation?lang=en#c4s1 |access-date=2024-05-19 |website=Atlas of Sustainable Development Goals 2023 |language=en}}</ref>|other=|label1=[[Glaciers]]|value1=69|color1=#AFEEEE|label2=[[Groundwater]]|value2=30|color2=#1E90FF|label3=Other Freshwater (e.g., Soil Moisture)|value3=0.7|color3=#ef8e39|label4=Directly Accessible Water|value4=0.3|color4=#000080}}Natural sources of [[fresh water]] include [[surface water]], under river flow, [[groundwater]] and [[frozen water]]. |
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{{Further|Water distribution on Earth}} |
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Natural sources of [[fresh water]] include [[surface water]], under river flow, [[groundwater]] and [[frozen water]]. |
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=== Surface water === |
=== Surface water === |
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Humans often increase storage capacity by constructing reservoirs and decrease it by draining wetlands. Humans often increase runoff quantities and velocities by paving areas and channelizing the stream flow. |
Humans often increase storage capacity by constructing reservoirs and decrease it by draining wetlands. Humans often increase runoff quantities and velocities by paving areas and channelizing the stream flow. |
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Natural surface water can be augmented by importing surface water from another watershed through a [[canal]] or [[Pipeline transport|pipeline]]. |
Natural surface water can be augmented by importing surface water from another watershed through a [[canal]] or [[Pipeline transport|pipeline]]. |
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[[Brazil]] is estimated to have the largest supply of fresh water in the world, followed by [[Russia]] and [[Canada]].<ref>{{cite web|url=http://www.worldwater.org/data.html |title=The World's Water 2006–2007 Tables, Pacific Institute |publisher=Worldwater.org |access-date=2009-03-12}}</ref> |
[[Brazil]] is estimated to have the largest supply of fresh water in the world, followed by [[Russia]] and [[Canada]].<ref>{{cite web|url=http://www.worldwater.org/data.html |title=The World's Water 2006–2007 Tables, Pacific Institute |publisher=Worldwater.org |access-date=2009-03-12}}</ref> |
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== Artificial sources of usable water == |
== Artificial sources of usable water == |
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There are several artificial sources of fresh water. One is [[Wastewater treatment|treated wastewater]] ([[reclaimed water]]). Another is [[atmospheric water generator]]s.<ref>{{cite journal |last1=Shafeian |first1=Nafise |last2=Ranjbar |first2=A.A. |last3=Gorji |first3=Tahereh B. |title=Progress in atmospheric water generation systems: A review |journal=Renewable and Sustainable Energy Reviews |date=June 2022 |volume=161 |pages=112325 |doi=10.1016/j.rser.2022.112325 |s2cid=247689027 |language=en}}</ref><ref>{{cite journal |last1=Jarimi |first1=Hasila |last2=Powell |first2=Richard |last3=Riffat |first3=Saffa |title=Review of sustainable methods for atmospheric water harvesting |journal=International Journal of Low-Carbon Technologies |date=18 May 2020 |volume=15 |issue=2 |pages=253–276 |doi=10.1093/ijlct/ctz072|doi-access=free }}</ref><ref>{{cite journal |last1=Raveesh |first1=G. |last2=Goyal |first2=R. |last3=Tyagi |first3=S.K. |title=Advances in atmospheric water generation technologies |journal=Energy Conversion and Management |date=July 2021 |volume=239 |pages=114226 |doi=10.1016/j.enconman.2021.114226|bibcode=2021ECM...23914226R |s2cid=236264708 }}</ref> [[Desalination|Desalinated seawater]] is another important source. It is important to consider the economic and environmental side effects of these technologies.<ref>{{Cite journal|last1=van Vliet|first1=Michelle T H|last2=Jones|first2=Edward R|last3=Flörke|first3=Martina|last4=Franssen|first4=Wietse H P|last5=Hanasaki|first5=Naota|last6=Wada|first6=Yoshihide|last7=Yearsley|first7=John R|date=2021-02-01|title=Global water scarcity including surface water quality and expansions of clean water technologies|journal=Environmental Research Letters|volume=16|issue=2|pages=024020|bibcode=2021ERL....16b4020V|doi=10.1088/1748-9326/abbfc3|issn=1748-9326|doi-access=free}}</ref> |
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=== Wastewater reuse === |
=== Wastewater reuse === |
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==== Air-capture over oceans ==== |
==== Air-capture over oceans ==== |
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[[File:Schematic_illustration_of_a_proposed_approach_for_capturing_moisture_above_the_ocean_surface_and_transporting_it_to_proximal_land_for_improving_water_security.webp|thumb|Schematic illustration of a proposed approach for capturing moisture above the ocean surface and transporting it to proximal land for improving [[water security]]<ref name="10.1038/s41598-022-24314-2">{{cite journal |last1=Rahman |first1=Afeefa |last2=Kumar |first2=Praveen |last3=Dominguez |first3=Francina |date=6 December 2022 |title=Increasing freshwater supply to sustainably address global water security at scale |journal=Scientific Reports |language=en |volume=12 |issue=1 |pages=20262 |bibcode=2022NatSR..1220262R |doi=10.1038/s41598-022-24314-2 |issn=2045-2322 |pmc=9726751 |pmid=36473864 |doi-access=free}} |
[[File:Schematic_illustration_of_a_proposed_approach_for_capturing_moisture_above_the_ocean_surface_and_transporting_it_to_proximal_land_for_improving_water_security.webp|thumb|Schematic illustration of a proposed approach for capturing moisture above the ocean surface and transporting it to proximal land for improving [[water security]]<ref name="10.1038/s41598-022-24314-2">{{cite journal |last1=Rahman |first1=Afeefa |last2=Kumar |first2=Praveen |last3=Dominguez |first3=Francina |date=6 December 2022 |title=Increasing freshwater supply to sustainably address global water security at scale |journal=Scientific Reports |language=en |volume=12 |issue=1 |pages=20262 |bibcode=2022NatSR..1220262R |doi=10.1038/s41598-022-24314-2 |issn=2045-2322 |pmc=9726751 |pmid=36473864 |doi-access=free}} |
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*University press release: {{cite news |title=Researchers propose new structures to harvest untapped source of freshwater |language=en |work=University of Illinois at Urbana-Champaign via techxplore.com |url=https://techxplore.com/news/2022-12-harvest-untapped-source-freshwater.html |access-date=17 January 2023}}</ref>]] |
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[[File:Spatial variability of water yield along the delineated near-offshore region of 200 km across the world.webp|thumb|Map of water stress and spatial variability of water yield along the delineated near-offshore region of 200 km across the world<ref name="10.1038/s41598-022-24314-2" />]] |
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* University press release: {{cite news |title=Researchers propose new structures to harvest untapped source of freshwater |language=en |work=University of Illinois at Urbana-Champaign via techxplore.com |url=https://techxplore.com/news/2022-12-harvest-untapped-source-freshwater.html |access-date=17 January 2023}}</ref>]] |
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[[File:Spatial_variability_of_water_yield_along_the_delineated_near-offshore_region_of_200_km_across_the_world.webp|thumb|Map of water stress and spatial variability of water yield along the delineated near-offshore region of 200 km across the world<ref name="10.1038/s41598-022-24314-2" />]] |
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Researchers proposed "significantly increasing freshwater through the [[Atmospheric water generator|capture of humid air]] over oceans" to address present and, especially, future water scarcity/insecurity.<ref>{{cite news |last1=McDonald |first1=Bob |title=Water, water, everywhere — and maybe here's how to make it drinkable |url=https://www.cbc.ca/radio/quirks/water-water-everywhere-and-maybe-here-s-how-to-make-it-drinkable-1.6703854 |access-date=17 January 2023}}</ref><ref name="10.1038/s41598-022-24314-2" /> |
Researchers proposed "significantly increasing freshwater through the [[Atmospheric water generator|capture of humid air]] over oceans" to address present and, especially, future water scarcity/insecurity.<ref>{{cite news |last1=McDonald |first1=Bob |title=Water, water, everywhere — and maybe here's how to make it drinkable |url=https://www.cbc.ca/radio/quirks/water-water-everywhere-and-maybe-here-s-how-to-make-it-drinkable-1.6703854 |access-date=17 January 2023}}</ref><ref name="10.1038/s41598-022-24314-2" /> |
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== Water uses == |
== Water uses == |
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[[File:Total Renewable Freshwater Resources in mm per year By WaterGAP Average 1961-1990.jpg|thumb|Total renewable freshwater resources of the world, in mm/year (1 mm is equivalent to 1 L of water per m<sup>2</sup>) (long-term average for the years |
[[File:Total Renewable Freshwater Resources in mm per year By WaterGAP Average 1961-1990.jpg|thumb|Total renewable freshwater resources of the world, in mm/year (1 mm is equivalent to 1 L of water per m<sup>2</sup>) (long-term average for the years 1961–1990). Resolution is 0.5° longitude x 0.5° latitude (equivalent to 55 km x 55 km at the equator). Computed by the global freshwater model [[WaterGAP]].]]The total quantity of water available at any given time is an important consideration. Some human water users have an intermittent need for water. For example, many [[farm]]s require large quantities of water in the spring, and no water at all in the winter. Other users have a continuous need for water, such as a [[power plant]] that requires water for cooling. Over the long term the average rate of precipitation within a watershed is the upper bound for average consumption of natural surface water from that watershed. |
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=== Agriculture and other irrigation=== |
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{{Main|Irrigation}} |
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It is estimated that 70% of worldwide water is used for [[irrigation]], with 15–35% of irrigation withdrawals being unsustainable.<ref name="WBCSD Water Facts & Trends">{{cite web|url=http://www.wbcsd.org/includes/getTarget.asp?type=d&id=MTYyNTA |title=WBCSD Water Facts & Trends |access-date=2009-03-12}}</ref> It takes around 2,000 – 3,000 litres of water to produce enough food to satisfy one person's daily dietary need.<ref>[https://web.archive.org/web/20150306032041/http://www.fao.org/nr/water/docs/escarcity.pdf UN Water – Coping with Water Scarcity 2007]. fao.org</ref> This is a considerable amount, when compared to that required for drinking, which is between two and five litres. To produce food for the now over 7 billion people who inhabit the planet today requires the water that would fill a canal ten metres deep, 100 metres wide and 2100 kilometres long.<!-- Calculation is 7000000000x3000 litres =21000000000 M3. Cross section of hypothetical canal = 1000 M3. Thus length is 21000000 Metres or 21000 Km --> |
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An assessment of water management in agriculture sector was conducted in 2007 by the [[International Water Management Institute]] in [[Sri Lanka]] to see if the world had sufficient water to provide food for its growing population.<ref>Molden, D. (Ed.) (2007) ''Water for food, Water for life: [[A Comprehensive Assessment of Water Management in Agriculture]].'' Earthscan/IWMI.</ref> It assessed the current availability of water for agriculture on a global scale and mapped out locations suffering from water scarcity. It found that a fifth of the world's people, more than 1.2 billion, live in areas of [[physical water scarcity]], where there is not enough water to meet all demands. A further 1.6 billion people live in areas experiencing [[economic water scarcity]], where the lack of investment in water or insufficient human capacity make it impossible for authorities to satisfy the demand for water. The report found that it would be possible to produce the food required in future, but that continuation of today's food production and environmental trends would lead to crises in many parts of the world. To avoid a global water crisis, farmers will have to strive to increase productivity to meet growing demands for food, while industry and cities find ways to use water more efficiently.<ref>Chartres, C. and Varma, S. (2010) ''Out of water. From Abundance to Scarcity and How to Solve the World's Water Problems'' FT Press (US).</ref><ref>{{Cite book|last=Haie|first=Naim|url=https://link.springer.com/content/pdf/bfm%3A978-981-15-6284-6%2F1.pdf|title=Transparent Water Management Theory: Sefficiency in Sequity|publisher=Springer|year=2020}}</ref> |
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In some areas of the world, irrigation is necessary to grow any crop at all, in other areas it permits more profitable crops to be grown or enhances crop yield. Various irrigation methods involve different trade-offs between crop yield, water consumption and capital cost of equipment and structures. Irrigation methods such as [[furrow irrigation|furrow]] and overhead [[irrigation sprinkler|sprinkler]] irrigation are usually less expensive but are also typically less efficient, because much of the water evaporates, runs off or drains below the root zone. Other irrigation methods considered to be more efficient include [[drip irrigation|drip or trickle irrigation]], [[surface irrigation#Surge irrigation|surge irrigation]], and some types of sprinkler systems where the sprinklers are operated near ground level. These types of systems, while more expensive, usually offer greater potential to minimize runoff, drainage and evaporation. Any system that is improperly managed can be wasteful, all methods have the potential for high efficiencies under suitable conditions, appropriate irrigation timing and management. Some issues that are often insufficiently considered are salinization of groundwater and contaminant accumulation leading to water quality declines. |
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As global populations grow, and as demand for food increases, there are efforts under way to learn how to produce more food with [[Water supply|less water]], through improvements in irrigation<ref>{{cite web|url=http://www.fao.org/nr/water/topics_irrigation.html |title=Water Development and Management Unit – Topics – Irrigation |publisher=FAO |access-date=2009-03-12}}</ref> methods<ref>{{cite web|url=http://www.fao.org/nr/water/news/masscote.html |title=FAO Water Unit | Water News: water scarcity |publisher=Fao.org |access-date=2009-03-12}}</ref> and [[technologies]], agricultural [[water management]], crop types, and water monitoring. [[Aquaculture]] is a small but growing agricultural use of water. Freshwater commercial fisheries may also be considered as agricultural uses of water, but have generally been assigned a lower priority than irrigation (see [[Aral Sea]] and [[Pyramid Lake (Nevada)|Pyramid Lake]]). |
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Changing landscape for the use of agriculture has a great effect on the flow of fresh water. Changes in landscape by the removal of trees and [[soil]]s changes the flow of fresh water in the local environment and also affects the cycle of fresh water. As a result, more fresh water is stored in the soil which benefits the agriculture. However, since agriculture is the human activity that consumes the most fresh water,<ref name="Gordon">{{cite journal|author=Gordon L., D. M. |year=2003|title= Land cover change and water vapour flows: learning from Australia|volume= 358 |issue=1440|pages= 1973–1984|doi=10.1098/rstb.2003.1381 |jstor=3558315|journal=Philosophical Transactions of the Royal Society B: Biological Sciences |pmid=14728792 |pmc=1693281}}</ref> this can put a severe strain on local freshwater resources resulting in the destruction of local [[ecosystem]]s. |
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In [[Australia]], over-abstraction of fresh water for intensive [[irrigation]] activities has caused 33% of the land area to be at risk of [[Soil salinity|salination]].<ref name="Gordon" /> |
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{| class="wikitable" |
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|+Water requirements of different classes of livestock<ref>{{cite web|url=http://extension.oregonstate.edu/douglas/sites/default/files/documents/lf/WATERLF0503.pdf|title=How much does a cow need ?|last=Filley|first=S|archive-url=https://web.archive.org/web/20120512155949/http://extension.oregonstate.edu/douglas/sites/default/files/documents/lf/WATERLF0503.pdf|archive-date=12 May 2012|url-status=dead|access-date=17 March 2012|df=dmy-all}}</ref> |
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! Animal !! Average / day !! Range / day |
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| [[Dairy cattle|Dairy cow]] || {{convert|20|USgal|L|0|order=flip|abbr=on}} || {{convert|15|to|25|USgal|L|0|order=flip|abbr=on}} |
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|- |
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| Cow-calf pair || {{convert|15|USgal|L|0|order=flip|abbr=on}} || {{convert|2|to|20|USgal|L|0|order=flip|abbr=on}} |
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|- |
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| Yearling cattle || {{convert|10|USgal|L|0|order=flip|abbr=on}} || {{convert|6|to|14|USgal|L|0|order=flip|abbr=on}} |
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|- |
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| Horse || {{convert|10|USgal|L|0|order=flip|abbr=on}} || {{convert|8|to|14|USgal|L|0|order=flip|abbr=on}} |
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|- |
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| Sheep || {{convert|2|USgal|L|0|order=flip|abbr=on}} ||{{convert|2|to|3|USgal|L|0|order=flip|abbr=on}} |
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|} |
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<br /> |
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{| class="wikitable" |
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|+Approximate values of seasonal crop water needs<ref>{{cite web|url=http://www.fao.org/docrep/S2022E/s2022e02.htm|title=Crops Need Water|last=Natural Resource Management and Environmental Dept|archive-url=https://web.archive.org/web/20120116073927/http://www.fao.org/docrep/S2022E/s2022e02.htm|archive-date=16 January 2012|url-status=live|access-date=17 March 2012|df=dmy-all}}</ref> |
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! Crop !! Crop water needs mm / total growing period |
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|Sugar Cane |
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|1500–2500 |
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| Banana || 1200–2200 |
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|Citrus |
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|900–1200 |
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|Potato |
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|500–700 |
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|- |
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|Tomato |
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|400–800 |
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|- |
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| Barley/Oats/Wheat || 450–650 |
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|- |
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| Cabbage || 350–500 |
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|- |
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| Onions || 350–550 |
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|- |
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| Pea || 350–500 |
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|} |
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====Irrigation of green spaces and golf courses==== |
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{{Further|Greening}} |
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[[Urban green space]]s and golf courses usually require some form of irrigation. [[Golf course]]s are often targeted as using excessive amounts of water, especially in drier regions. Many golf courses utilize either primarily or exclusively treated effluent water, which has little impact on potable water availability. |
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=== Industries === |
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===Agriculture and other irrigation=== |
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[[File:Poland Solina dam.jpg|thumb|A power plant in [[Poland]]]] |
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{{Further|Sustainable Water and Innovative Irrigation Management}} |
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{{excerpt|Irrigation|paragraphs=1-3}} |
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=== Industries === |
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It is estimated that 22% of worldwide water is used in [[Industrial sector|industry]].<ref name="WBCSD Water Facts & Trends" /> Major industrial users include [[hydroelectric]] dams, [[Electricity generation#Other generation methods|thermoelectric power plants]], which use water for [[cooling]], [[ore]] and [[oil refineries]], which use water in [[chemical process]]es, and manufacturing plants, which use water as a [[solvent]]. Water withdrawal can be very high for certain industries, but consumption is generally much lower than that of agriculture. |
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{{See also|Industrial water treatment|Industrial wastewater treatment}}It is estimated that 22% of worldwide water is used in [[Industrial sector|industry]].<ref name="WBCSD Water Facts & Trends">{{cite web |url=http://www.wbcsd.org/includes/getTarget.asp?type=d&id=MTYyNTA |title=WBCSD Water Facts & Trends |access-date=2009-03-12 |archive-date=2012-03-01 |archive-url=https://web.archive.org/web/20120301011840/http://www.wbcsd.org/includes/getTarget.asp?type=d&id=MTYyNTA |url-status=dead }}</ref> Major industrial users include [[hydroelectric]] dams, [[Electricity generation#Other generation methods|thermoelectric power plants]], which use water for [[cooling]], [[ore]] and [[oil refineries]], which use water in [[chemical process]]es, and manufacturing plants, which use water as a [[solvent]]. Water withdrawal can be very high for certain industries, but consumption is generally much lower than that of agriculture. |
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Water is used in [[renewable power]] generation. [[Hydroelectric Power|Hydroelectric power]] derives energy from the force of water flowing downhill, driving a turbine connected to a generator. This hydroelectricity is a low-cost, non-polluting, renewable energy source. Significantly, hydroelectric power can also be used for [[load following]] unlike most renewable energy sources which are [[Intermittent energy source|intermittent]]. Ultimately, the energy in a hydroelectric power plant is supplied by the sun. Heat from the sun evaporates water, which condenses as rain in higher altitudes and flows downhill. [[Pumped-storage hydroelectricity|Pumped-storage hydroelectric]] plants also exist, which use grid electricity to pump water uphill when demand is low, and use the stored water to produce electricity when demand is high. |
Water is used in [[renewable power]] generation. [[Hydroelectric Power|Hydroelectric power]] derives energy from the force of water flowing downhill, driving a turbine connected to a generator. This hydroelectricity is a low-cost, non-polluting, renewable energy source. Significantly, hydroelectric power can also be used for [[load following]] unlike most renewable energy sources which are [[Intermittent energy source|intermittent]]. Ultimately, the energy in a hydroelectric power plant is supplied by the sun. Heat from the sun evaporates water, which condenses as rain in higher altitudes and flows downhill. [[Pumped-storage hydroelectricity|Pumped-storage hydroelectric]] plants also exist, which use grid electricity to pump water uphill when demand is low, and use the stored water to produce electricity when demand is high. |
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Thermoelectric power plants using [[cooling towers]] have high consumption, nearly equal to their withdrawal, as most of the withdrawn water is evaporated as part of the cooling process. The withdrawal, however, is lower than in [[once-through cooling]] systems. |
Thermoelectric power plants using [[cooling towers]] have high consumption, nearly equal to their withdrawal, as most of the withdrawn water is evaporated as part of the cooling process. The withdrawal, however, is lower than in [[once-through cooling]] systems. |
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Water is also used in many large scale industrial processes, such as thermoelectric power production, oil refining, [[fertilizer]] production and other [[chemical plant]] use, and [[natural gas extraction]] from [[shale rock]]. Discharge of untreated water from industrial uses is [[pollution]]. Pollution includes discharged solutes and increased water temperature ([[thermal pollution]]). |
Water is also used in many large scale industrial processes, such as thermoelectric power production, oil refining, [[fertilizer]] production and other [[chemical plant]] use, and [[natural gas extraction]] from [[shale rock]]. Discharge of untreated water from industrial uses is [[pollution]]. Pollution includes discharged solutes and increased water temperature ([[thermal pollution]]). |
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=== Drinking water and domestic use (households) === |
=== Drinking water and domestic use (households) === |
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844 million people still lacked even a basic drinking water service in 2017.<ref name=":7">{{Cite book|last1=WHO|first1=UNICEF|url=https://www.susana.org/en/knowledge-hub/resources-and-publications/library/details/2805|title=Progress on drinking water, sanitation and hygiene : 2017 update and SDG baselines.|year=2017|isbn=978-9241512893|location=Geneva|oclc=1010983346}}</ref>{{rp|3}} Of those, 159 million people worldwide drink water directly from surface water sources, such as lakes and streams.<ref name=":7" />{{rp|3}} One in eight people in the world do not have access to safe water.<ref>{{Cite web|date=2018-11-09|title=Global WASH Fast Facts {{!}} Global Water, Sanitation and Hygiene {{!}} Healthy Water {{!}} CDC|url=https://www.cdc.gov/healthywater/global/wash_statistics.html|access-date=2019-04-09|website=www.cdc.gov|language=en-us}}</ref><ref>{{cite web|last=Water Aid|title=Water|url=http://www.wateraid.org/uk/what_we_do/the_need/5899.asp?gclid=CMvwnO7B164CFUcRfAodFkdffg|url-status=dead|archive-url=https://archive.today/20130416024534/http://www.wateraid.org/uk/what_we_do/the_need/5899.asp?gclid=CMvwnO7B164CFUcRfAodFkdffg|archive-date=16 April 2013|access-date=17 March 2012}}</ref> |
844 million people still lacked even a basic drinking water service in 2017.<ref name=":7">{{Cite book|last1=WHO|first1=UNICEF|url=https://www.susana.org/en/knowledge-hub/resources-and-publications/library/details/2805|title=Progress on drinking water, sanitation and hygiene : 2017 update and SDG baselines.|year=2017|isbn=978-9241512893|location=Geneva|oclc=1010983346}}</ref>{{rp|3}} Of those, 159 million people worldwide drink water directly from surface water sources, such as lakes and streams.<ref name=":7" />{{rp|3}} One in eight people in the world do not have access to safe water.<ref>{{Cite web|date=2018-11-09|title=Global WASH Fast Facts {{!}} Global Water, Sanitation and Hygiene {{!}} Healthy Water {{!}} CDC|url=https://www.cdc.gov/healthywater/global/wash_statistics.html|access-date=2019-04-09|website=www.cdc.gov|language=en-us}}</ref><ref>{{cite web|last=Water Aid|title=Water|url=http://www.wateraid.org/uk/what_we_do/the_need/5899.asp?gclid=CMvwnO7B164CFUcRfAodFkdffg|url-status=dead|archive-url=https://archive.today/20130416024534/http://www.wateraid.org/uk/what_we_do/the_need/5899.asp?gclid=CMvwnO7B164CFUcRfAodFkdffg|archive-date=16 April 2013|access-date=17 March 2012}}</ref> |
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=== Environment === |
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Explicit environment water use is also a very small but growing percentage of total water use. Environmental water may include water stored in impoundments and released for environmental purposes (held environmental water), but more often is water retained in waterways through regulatory limits of abstraction.<ref>National Water Commission (2010). Australian environmental water management report. NWC, Canberra</ref> Environmental water usage includes watering of natural or artificial wetlands, artificial lakes intended to create wildlife habitat, [[fish ladder]]s, and water releases from reservoirs timed to help fish spawn, or to restore more natural flow regimes.<ref>{{cite web|url=http://silkroadintelligencer.com/2010/07/27/aral-sea-trickles-back-to-life/ |title=Aral Sea trickles back to life |publisher=Silk Road Intelligencer |access-date=2011-12-05}}</ref> |
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Environmental usage is non-consumptive but may reduce the availability of water for other users at specific times and places. For example, water release from a reservoir to help fish spawn may not be available to farms upstream, and water retained in a river to maintain waterway health would not be available to water abstractors downstream. |
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=== Recreation === |
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{{Further|Sea#Leisure}} |
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[[Recreation]]al water use is mostly tied to lakes, dams, rivers or oceans. If a [[Reservoir|water reservoir]] is kept fuller than it would otherwise be for recreation, then the water retained could be categorized as recreational usage. Examples are anglers, water skiers, nature enthusiasts and swimmers. |
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Recreational usage is usually non-consumptive. However, recreational usage may reduce the availability of water for other users at specific times and places. For example, water retained in a reservoir to allow boating in the late summer is not available to farmers during the spring planting season. Water released for whitewater rafting may not be available for hydroelectric generation during the time of peak electrical demand. |
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== Challenges and threats == |
== Challenges and threats == |
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=== Water scarcity === |
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Threats for the availability of water resources include: Water scarcity, water pollution, water conflict and [[Effects of climate change|climate change]]. |
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=== Water scarcity === |
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{{excerpt|Water scarcity|paragraphs=1|file=no}} |
{{excerpt|Water scarcity|paragraphs=1|file=no}} |
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{{Further|Effects of climate change on the water cycle}} |
{{Further|Effects of climate change on the water cycle}} |
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{{excerpt|Water security#Climate change|paragraphs=1|file=no}}<!-- this takes the first two paragraphs of the lead of the sub-article --> |
{{excerpt|Water security#Climate change|paragraphs=1|file=no}}<!-- this takes the first two paragraphs of the lead of the sub-article --> |
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=== Groundwater overdrafting === |
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The world's supply of [[groundwater]] is steadily decreasing. Groundwater depletion (or [[overdrafting]]) is occurring for example in Asia, South America and North America. It is still unclear how much natural renewal [[water balance|balances]] this usage, and whether [[ecosystem]]s are threatened.<ref>{{cite journal |last1=Gleeson |first1=Tom |last2=Wada |first2=Yoshihide |last3=Bierkens |first3=Marc F. P. |last4=van Beek |first4=Ludovicus P. H. |date=9 August 2012 |title=Water balance of global aquifers revealed by groundwater footprint |journal=[[Nature (journal)|Nature]] |volume=488 |issue=7410 |pages=197–200 |bibcode=2012Natur.488..197G |doi=10.1038/nature11295 |pmid=22874965 |s2cid=4393813}}</ref> |
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{{excerpt|overdrafting|paragraphs=1}} |
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== Water resource management == |
== Water resource management == |
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{{Further|Water resources law|}} |
{{Further|Water resources law|}} |
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[[File:Global Values of Water Resources and Water Use.jpg|thumb|upright=1.8|Global values of water resources and human water use (excluding [[Antarctica]]). Water resources 1961-90, water use around 2000. Computed by the global freshwater model [[WaterGAP]].]] |
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Water resource management is the activity of planning, developing, distributing and managing the optimum use of water resources. It is an aspect of [[water cycle management]]. The field of water resources management will have to continue to adapt to the current and future issues facing the allocation of water. With the growing uncertainties of global [[climate change]] and the long-term impacts of past management actions, this decision-making will be even more difficult. It is likely that ongoing climate change will lead to situations that have not been encountered. As a result, alternative management strategies, including participatory approaches and [[adaptive capacity]] are increasingly being used to strengthen water decision-making. |
Water resource management is the activity of planning, developing, distributing and managing the optimum use of water resources. It is an aspect of [[water cycle management]]. The field of water resources management will have to continue to adapt to the current and future issues facing the allocation of water. With the growing uncertainties of global [[climate change]] and the long-term impacts of past management actions, this decision-making will be even more difficult. It is likely that ongoing climate change will lead to situations that have not been encountered. As a result, alternative management strategies, including participatory approaches and [[adaptive capacity]] are increasingly being used to strengthen water decision-making. |
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Ideally, water resource management planning has regard to all the competing [[Demand for water|demands for water]] and seeks to allocate water on an equitable basis to satisfy all uses and demands. As with other [[resource management]], this is rarely possible in practice so decision-makers must prioritise issues of sustainability, equity and factor optimisation (in that order!) to achieve acceptable outcomes. One of the biggest concerns for water-based resources in the future is the [[sustainability]] of the current and future water resource allocation. |
Ideally, water resource management planning has regard to all the competing [[Demand for water|demands for water]] and seeks to allocate water on an equitable basis to satisfy all uses and demands. As with other [[resource management]], this is rarely possible in practice so decision-makers must prioritise issues of sustainability, equity and factor optimisation (in that order!) to achieve acceptable outcomes. One of the biggest concerns for water-based resources in the future is the [[sustainability]] of the current and future water resource allocation. |
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[[Sustainable Development Goal 6]] has a target related to water resources management: "Target 6.5: By 2030, implement integrated water resources management at all levels, including through transboundary cooperation as appropriate."<ref name=":3">Ritchie, Roser, Mispy, Ortiz-Ospina (2018) [https://sdg-tracker.org/water-and-sanitation "Measuring progress towards the Sustainable Development Goals." (SDG 6)] ''SDG-Tracker.org, website''</ref><ref name=":17">United Nations (2017) Resolution adopted by the General Assembly on 6 July 2017, [[:File:A RES 71 313 E.pdf|Work of the Statistical Commission pertaining to the 2030 Agenda for Sustainable Development]] ([https://undocs.org/A/RES/71/313 A/RES/71/313])</ref> |
[[Sustainable Development Goal 6]] has a target related to water resources management: "Target 6.5: By 2030, implement integrated water resources management at all levels, including through transboundary cooperation as appropriate."<ref name=":3">Ritchie, Roser, Mispy, Ortiz-Ospina (2018) [https://sdg-tracker.org/water-and-sanitation "Measuring progress towards the Sustainable Development Goals." (SDG 6)] ''SDG-Tracker.org, website''</ref><ref name=":17">United Nations (2017) Resolution adopted by the General Assembly on 6 July 2017, [[:File:A RES 71 313 E.pdf|Work of the Statistical Commission pertaining to the 2030 Agenda for Sustainable Development]] ([https://undocs.org/A/RES/71/313 A/RES/71/313])</ref> |
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At present, only about 0.08 percent of all the world's fresh water is accessible. And there is ever-increasing demand for [[Drinking water|drinking]], [[manufacturing]], [[Water sports|leisure]] and [[agriculture]]. Due to the small percentage of water available, optimizing the fresh water we have left from [[natural resources]] has been a growing challenge around the world. |
At present, only about 0.08 percent of all the world's fresh water is accessible. And there is ever-increasing demand for [[Drinking water|drinking]], [[manufacturing]], [[Water sports|leisure]] and [[agriculture]]. Due to the small percentage of water available, optimizing the fresh water we have left from [[natural resources]] has been a growing challenge around the world. |
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Much effort in water resource management is directed at optimizing the [[Water use|use of water]] and in minimizing the [[environmental impact]] of water use on the natural environment. The observation of water as an integral part of the [[ecosystem]] is based on [[integrated water resources management]], based on the 1992 [[Dublin Statement|Dublin Principles]] (see below). |
Much effort in water resource management is directed at optimizing the [[Water use|use of water]] and in minimizing the [[environmental impact]] of water use on the natural environment. The observation of water as an integral part of the [[ecosystem]] is based on [[integrated water resources management]], based on the 1992 [[Dublin Statement|Dublin Principles]] (see below). |
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Sustainable water management requires a holistic approach based on the principles of [[Integrated water resources management|Integrated Water Resource Management]], originally articulated in 1992 at the Dublin (January) and Rio (July) conferences. The four Dublin Principles, promulgated in the [[Dublin Statement]] are: |
Sustainable water management requires a holistic approach based on the principles of [[Integrated water resources management|Integrated Water Resource Management]], originally articulated in 1992 at the Dublin (January) and Rio (July) conferences. The four Dublin Principles, promulgated in the [[Dublin Statement]] are: |
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Some scholars say that IWRM is complementary to [[water security]] because water security is a goal or destination, whilst IWRM is the process necessary to achieve that goal.<ref name=":1">{{cite book |last1=Sadoff |first1=Claudia |title=Oxford Research Encyclopedia of Environmental Science |last2=Grey |first2=David |last3=Borgomeo |first3=Edoardo |year=2020 |isbn=978-0-19-938941-4 |chapter=Water Security |doi=10.1093/acrefore/9780199389414.013.609}}</ref> |
Some scholars say that IWRM is complementary to [[water security]] because water security is a goal or destination, whilst IWRM is the process necessary to achieve that goal.<ref name=":1">{{cite book |last1=Sadoff |first1=Claudia |title=Oxford Research Encyclopedia of Environmental Science |last2=Grey |first2=David |last3=Borgomeo |first3=Edoardo |year=2020 |isbn=978-0-19-938941-4 |chapter=Water Security |doi=10.1093/acrefore/9780199389414.013.609}}</ref> |
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IWRM is a paradigm that emerged at international conferences in the late 1900s and early 2000s, although participatory water management institutions have existed for centuries.<ref name=":0">{{Cite journal |last1=Rahaman |first1=Muhammad Mizanur |last2=Varis |first2=Olli |date=April 2005 |title=Integrated water resources management: evolution, prospects and future challenges |journal=Sustainability: Science, Practice and Policy |language=en |volume=1 |issue=1 |pages=15–21 |doi=10.1080/15487733.2005.11907961 |s2cid=10057051 |issn=1548-7733|doi-access=free }}</ref> Discussions on a holistic way of managing water resources began already in the 1950s leading up to the 1977 United Nations Water Conference.<ref>Asit K.B. (2004). Integrated Water Resources Management: A Reassessment, Water International, 29(2), 251</ref> The development of IWRM was particularly recommended in the final statement of the ministers at the International Conference on Water and the Environment in 1992, known as the [[Dublin Statement]]. This concept aims to promote changes in practices which are considered fundamental to improved [[water resource management]]. IWRM was a topic of [[World Water Forum#2nd World Water Forum: Netherlands|the second World Water Forum]], which was attended by a more varied group of stakeholders than the preceding conferences and contributed to the creation of the GWP.<ref name=":0" /> |
IWRM is a paradigm that emerged at international conferences in the late 1900s and early 2000s, although participatory water management institutions have existed for centuries.<ref name=":0">{{Cite journal |last1=Rahaman |first1=Muhammad Mizanur |last2=Varis |first2=Olli |date=April 2005 |title=Integrated water resources management: evolution, prospects and future challenges |journal=Sustainability: Science, Practice and Policy |language=en |volume=1 |issue=1 |pages=15–21 |doi=10.1080/15487733.2005.11907961 |s2cid=10057051 |issn=1548-7733|doi-access=free |bibcode=2005SSPP....1...15R }}</ref> Discussions on a holistic way of managing water resources began already in the 1950s leading up to the 1977 United Nations Water Conference.<ref>Asit K.B. (2004). Integrated Water Resources Management: A Reassessment, Water International, 29(2), 251</ref> The development of IWRM was particularly recommended in the final statement of the ministers at the International Conference on Water and the Environment in 1992, known as the [[Dublin Statement]]. This concept aims to promote changes in practices which are considered fundamental to improved [[water resource management]]. IWRM was a topic of [[World Water Forum#2nd World Water Forum: Netherlands|the second World Water Forum]], which was attended by a more varied group of stakeholders than the preceding conferences and contributed to the creation of the GWP.<ref name=":0" /> |
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In the [[International Water Association]] definition, IWRM rests upon three principles that together act as the overall framework:<ref>{{Cite web|title=Integrated Water Resources Management: Basic Concepts {{!}} IWA Publishing|url=https://www.iwapublishing.com/news/integrated-water-resources-management-basic-concepts|access-date=2020-11-18|website=www.iwapublishing.com}}</ref> |
In the [[International Water Association]] definition, IWRM rests upon three principles that together act as the overall framework:<ref>{{Cite web|title=Integrated Water Resources Management: Basic Concepts {{!}} IWA Publishing|url=https://www.iwapublishing.com/news/integrated-water-resources-management-basic-concepts|access-date=2020-11-18|website=www.iwapublishing.com}}</ref> |
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# Social equity: ensuring equal access for all users (particularly marginalized and poorer user groups) to an adequate quantity and quality of water necessary to sustain human [[well-being]]. |
# Social equity: ensuring equal access for all users (particularly marginalized and poorer user groups) to an adequate quantity and quality of water necessary to sustain human [[well-being]]. |
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# Economic efficiency: bringing the greatest benefit to the greatest number of users possible with the available financial and water resources. |
# Economic efficiency: bringing the greatest benefit to the greatest number of users possible with the available financial and water resources. |
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# Ecological sustainability: requiring that [[aquatic ecosystem]]s are acknowledged as users and that adequate allocation is made to sustain their natural functioning. |
# Ecological sustainability: requiring that [[aquatic ecosystem]]s are acknowledged as users and that adequate allocation is made to sustain their natural functioning. |
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In 2002, the development of IWRM was discussed at [[Earth Summit 2002|the World Summit on Sustainable Development]] held in Johannesburg, which aimed to encourage the implementation of IWRM at a global level.<ref>{{Citation|last1=Ibisch|first1=Ralf B.|title=Integrated Water Resources Management: Concept, Research and Implementation|date=2016|url=http://link.springer.com/10.1007/978-3-319-25071-7_1|pages=3–32|editor-last=Borchardt|editor-first=Dietrich|place=Cham|publisher=Springer International Publishing|language=en|doi=10.1007/978-3-319-25071-7_1|isbn=978-3-319-25069-4|access-date=2020-11-14|last2=Bogardi|first2=Janos J.|last3=Borchardt|first3=Dietrich|editor2-last=Bogardi|editor2-first=Janos J.|editor3-last=Ibisch|editor3-first=Ralf B.}}</ref> [[World Water Forum#3rd World Water Forum: Japan|The third World Water Forum]] recommended IWRM and discussed information sharing, stakeholder participation, and gender and class dynamics.<ref name=":0" /> |
In 2002, the development of IWRM was discussed at [[Earth Summit 2002|the World Summit on Sustainable Development]] held in Johannesburg, which aimed to encourage the implementation of IWRM at a global level.<ref>{{Citation|last1=Ibisch|first1=Ralf B.|title=Integrated Water Resources Management: Concept, Research and Implementation|date=2016|url=http://link.springer.com/10.1007/978-3-319-25071-7_1|pages=3–32|editor-last=Borchardt|editor-first=Dietrich|place=Cham|publisher=Springer International Publishing|language=en|doi=10.1007/978-3-319-25071-7_1|isbn=978-3-319-25069-4|access-date=2020-11-14|last2=Bogardi|first2=Janos J.|last3=Borchardt|first3=Dietrich|editor2-last=Bogardi|editor2-first=Janos J.|editor3-last=Ibisch|editor3-first=Ralf B.}}</ref> [[World Water Forum#3rd World Water Forum: Japan|The third World Water Forum]] recommended IWRM and discussed information sharing, stakeholder participation, and gender and class dynamics.<ref name=":0" /> |
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IWRM practices depend on context; at the operational level, the challenge is to translate the agreed principles into concrete action. |
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Operationally, IWRM approaches involve applying knowledge from various disciplines as well as the insights from diverse stakeholders to devise and implement efficient, equitable and sustainable solutions to water and development problems. As such, IWRM is a comprehensive, [[participatory]] planning and implementation tool for managing and developing water resources in a way that balances social and economic needs, and that ensures the [[ecosystem protection|protection of ecosystems]] for future generations. In addition, in light of contributing the achievement of [[Sustainable Development Goals|Sustainable Development goals (SDGs)]],<ref>{{Cite book|url=http://link.springer.com/10.1007/978-3-319-75163-4|title=Managing Water, Soil and Waste Resources to Achieve Sustainable Development Goals|date=2018|publisher=Springer International Publishing|isbn=978-3-319-75162-7|editor-last=Hülsmann|editor-first=Stephan|location=Cham|language=en|doi=10.1007/978-3-319-75163-4|s2cid=135441230|editor-last2=Ardakanian|editor-first2=Reza}}</ref> IWRM has been evolving into more sustainable approach as it considers the Nexus approach, which is a cross-sectoral water resource management. The Nexus approach is based on the recognition that "water, energy and food are closely linked through global and local water, carbon and energy cycles or chains." |
Operationally, IWRM approaches involve applying knowledge from various disciplines as well as the insights from diverse stakeholders to devise and implement efficient, equitable and sustainable solutions to water and development problems. As such, IWRM is a comprehensive, [[participatory]] planning and implementation tool for managing and developing water resources in a way that balances social and economic needs, and that ensures the [[ecosystem protection|protection of ecosystems]] for future generations. In addition, in light of contributing the achievement of [[Sustainable Development Goals|Sustainable Development goals (SDGs)]],<ref>{{Cite book|url=http://link.springer.com/10.1007/978-3-319-75163-4|title=Managing Water, Soil and Waste Resources to Achieve Sustainable Development Goals|date=2018|publisher=Springer International Publishing|isbn=978-3-319-75162-7|editor-last=Hülsmann|editor-first=Stephan|location=Cham|language=en|doi=10.1007/978-3-319-75163-4|s2cid=135441230|editor-last2=Ardakanian|editor-first2=Reza}}</ref> IWRM has been evolving into more sustainable approach as it considers the Nexus approach, which is a cross-sectoral water resource management. The Nexus approach is based on the recognition that "water, energy and food are closely linked through global and local water, carbon and energy cycles or chains." |
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An IWRM approach aims at avoiding a fragmented approach of water resources management by considering the following aspects: Enabling environment, roles of Institutions, management Instruments. Some of the cross-cutting conditions that are also important to consider when implementing IWRM are: Political will and commitment, capacity development, adequate investment, [[financial stability]] and sustainable cost recovery, monitoring and evaluation. There is not one correct administrative model. The art of IWRM lies in selecting, adjusting and applying the right mix of these tools for a given situation. IWRM practices depend on context; at the operational level, the challenge is to translate the agreed principles into concrete action. |
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Water's many different uses — for agriculture, for healthy ecosystems, for people and livelihoods — demands coordinated action. An IWRM approach is consequently cross-sectoral, aiming to be an open, flexible process, and bringing all stakeholders to the table to set policy and make sound, balanced decisions in response to specific water challenges faced. |
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An IWRM approach focuses on three basics and aims at avoiding a fragmented approach of water resources management by considering the following aspects: |
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# Enabling Environment: A proper enabling environment is essential to both ensure the rights and assets of all stakeholders (individuals as well as public and private sector organizations and companies), and also to protect public assets such as intrinsic environmental values. |
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# Roles of Institutions: Institutional development is critical to the formulation and implementation of IWRM policies and programmes. Failure to match responsibilities, authority and capacities for action are all major sources of difficulty with implementing IWRM. |
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# Management Instruments: The management instruments for IWRM are the tools and methods that enable and help decision-makers to make rational and informed choices between alternative actions. |
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Some of the cross-cutting conditions that are also important to consider when implementing IWRM are: |
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* Political will and commitment |
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* Capacity development |
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* Adequate investment, [[financial stability]] and sustainable cost recovery |
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* Monitoring and evaluation |
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IWRM should be viewed as a process rather than a one-shot approach - one that is long-term and iterative rather than linear in nature. As a process which seeks to shift water development and management systems from their currently unsustainable forms, IWRM has no fixed beginnings or endings. |
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Furthermore, there is not one correct administrative model. The art of IWRM lies in selecting, adjusting and applying the right mix of these tools for a given situation. |
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=== Managing water in urban settings === |
=== Managing water in urban settings === |
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[[File:Urban Water Cycle - EPA 2004.png|thumb|Typical urban water cycle depicting drinking [[water purification]] and municipal [[sewage treatment]] systems]] |
[[File:Urban Water Cycle - EPA 2004.png|thumb|Typical urban water cycle depicting drinking [[water purification]] and municipal [[sewage treatment]] systems]] |
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{{ |
{{Excerpt|Integrated urban water management|paragraphs=1-2|file=no}} |
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==By country== |
==By country== |
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==See also== |
==See also== |
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{{Portal|Water}} |
{{Portal|Water}} |
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* [[Holistic management (agriculture)|Holistic management]] |
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* [[International trade and water]] |
* [[International trade and water]] |
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* [[List of sovereign states by freshwater withdrawal]] |
* [[List of sovereign states by freshwater withdrawal]] |
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* [[List of countries by total renewable water resources]] |
* [[List of countries by total renewable water resources]] |
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* [[Peak water]] |
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* [[Socio-hydrology]] |
* [[Socio-hydrology]] |
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* [[Virtual water]] |
* [[Virtual water]] |
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* [[Water resources law]] |
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* [[Water rights]] |
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* [[Water storage]] |
* [[Water storage]] |
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==References== |
==References== |
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{{ |
{{reflist|30em}} |
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==External links== |
==External links== |
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*[http://www.fao.org/ag/agl/aglw/aquastat/water_res/waterres_tab.htm Renewable water resources in the world by country] |
* [http://www.fao.org/ag/agl/aglw/aquastat/water_res/waterres_tab.htm Renewable water resources in the world by country] |
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*[http://www.hydrology.nl/ Portal to international hydrology and water resources] |
* [http://www.hydrology.nl/ Portal to international hydrology and water resources] |
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* [http://www.cap-net.org Cap-Net, Network for Capacity Building in Sustainable Water Management] |
* [http://www.cap-net.org/ Cap-Net, Network for Capacity Building in Sustainable Water Management] |
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* [http://www.cknet-ina.org CKnet-INA, Indonesian Integrated Water Resource Management Secretariat] |
* [http://www.cknet-ina.org/ CKnet-INA, Indonesian Integrated Water Resource Management Secretariat] |
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* [http://www.sswm.info Sustainable Sanitation and Water Management Toolbox] |
* [http://www.sswm.info/ Sustainable Sanitation and Water Management Toolbox] |
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{{Water}} |
{{Water}} |
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{{Natural resources}} |
{{Natural resources}} |
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{{Authority control}} |
{{Authority control}} |
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{{DEFAULTSORT:Water Resources}} |
{{DEFAULTSORT:Water Resources}} |
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[[Category:Aquatic ecology]] |
[[Category:Aquatic ecology]] |
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[[Category:Hydrology]] |
[[Category:Hydrology]] |
Water resources are natural resourcesofwater that are potentially useful for humans,[1] for example as a source of drinking water supplyorirrigation water. 97% of the water on Earth is salt water and only three percent is fresh water; slightly over two-thirds of this is frozen in glaciers and polar ice caps.[2] The remaining unfrozen freshwater is found mainly as groundwater, with only a small fraction present above ground or in the air.[3] Natural sources of fresh water include surface water, under river flow, groundwater and frozen water. Non-natural or human-made sources of fresh water can include wastewater that has been treated for reuse options, and desalinated seawater. People use water resources for agricultural, industrial and household activities.
Water resources are under threat from multiple issues. There is water scarcity, water pollution, water conflict and climate change. Fresh water is in principle a renewable resource. However, the world's supply of groundwater is steadily decreasing. Groundwater depletion (oroverdrafting) is occurring for example in Asia, South America and North America.
Natural sources of fresh water include surface water, under river flow, groundwater and frozen water.
Surface water is water in a river, lake or fresh water wetland. Surface water is naturally replenished by precipitation and naturally lost through discharge to the oceans, evaporation, evapotranspiration and groundwater recharge. The only natural input to any surface water system is precipitation within its watershed. The total quantity of water in that system at any given time is also dependent on many other factors. These factors include storage capacity in lakes, wetlands and artificial reservoirs, the permeability of the soil beneath these storage bodies, the runoff characteristics of the land in the watershed, the timing of the precipitation and local evaporation rates. All of these factors also affect the proportions of water loss.
Humans often increase storage capacity by constructing reservoirs and decrease it by draining wetlands. Humans often increase runoff quantities and velocities by paving areas and channelizing the stream flow.
Natural surface water can be augmented by importing surface water from another watershed through a canalorpipeline.
Brazil is estimated to have the largest supply of fresh water in the world, followed by Russia and Canada.[5]
Glacier runoff is considered to be surface water. The Himalayas, which are often called "The Roof of the World", contain some of the most extensive and rough high altitude areas on Earth as well as the greatest area of glaciers and permafrost outside of the poles. Ten of Asia's largest rivers flow from there, and more than a billion people's livelihoods depend on them. To complicate matters, temperatures there are rising more rapidly than the global average. In Nepal, the temperature has risen by 0.6 degrees Celsius over the last decade, whereas globally, the Earth has warmed approximately 0.7 degrees Celsius over the last hundred years.[6]
Groundwater is the water present beneath Earth's surface in rock and soil pore spaces and in the fracturesofrock formations. About 30 percent of all readily available freshwater in the world is groundwater.[7] A unit of rock or an unconsolidated deposit is called an aquifer when it can yield a usable quantity of water. The depth at which soil pore spaces or fractures and voids in rock become completely saturated with water is called the water table. Groundwater is recharged from the surface; it may discharge from the surface naturally at springs and seeps, and can form oasesorwetlands. Groundwater is also often withdrawn for agricultural, municipal, and industrial use by constructing and operating extraction wells. The study of the distribution and movement of groundwater is hydrogeology, also called groundwater hydrology.
Throughout the course of a river, the total volume of water transported downstream will often be a combination of the visible free water flow together with a substantial contribution flowing through rocks and sediments that underlie the river and its floodplain called the hyporheic zone. For many rivers in large valleys, this unseen component of flow may greatly exceed the visible flow. The hyporheic zone often forms a dynamic interface between surface water and groundwater from aquifers, exchanging flow between rivers and aquifers that may be fully charged or depleted. This is especially significant in karst areas where pot-holes and underground rivers are common.
There are several artificial sources of fresh water. One is treated wastewater (reclaimed water). Another is atmospheric water generators.[8][9][10] Desalinated seawater is another important source. It is important to consider the economic and environmental side effects of these technologies.[11]
Water reclamation is the process of converting municipal wastewater or sewage and industrial wastewater into water that can be reused for a variety of purposes . It is also called wastewater reuse, water reuse or water recycling. There are many types of reuse. It is possible to reuse water in this way in cities or for irrigation in agriculture. Other types of reuse are environmental reuse, industrial reuse, and reuse for drinking water, whether planned or not. Reuse may include irrigation of gardens and agricultural fields or replenishing surface water and groundwater. This latter is also known as groundwater recharge. Reused water also serve various needs in residences such as toilet flushing, businesses, and industry. It is possible to treat wastewater to reach drinking water standards. Injecting reclaimed water into the water supply distribution system is known as direct potable reuse. Drinking reclaimed water is not typical.[12] Reusing treated municipal wastewater for irrigation is a long-established practice. This is especially so in arid countries. Reusing wastewater as part of sustainable water management allows water to remain an alternative water source for human activities. This can reduce scarcity. It also eases pressures on groundwater and other natural water bodies.[13]
Desalination is a process that removes mineral components from saline water. More generally, desalination is the removal of salts and minerals from a substance.[16] One example is soil desalination. This is important for agriculture. It is possible to desalinate saltwater, especially sea water, to produce water for human consumptionorirrigation. The by-product of the desalination process is brine.[17] Many seagoing ships and submarines use desalination. Modern interest in desalination mostly focuses on cost-effective provision of fresh water for human use. Along with recycled wastewater, it is one of the few water resources independent of rainfall.[18]
Researchers proposed "significantly increasing freshwater through the capture of humid air over oceans" to address present and, especially, future water scarcity/insecurity.[24][23]
A potentials-assessment study proposed hypothetical portable solar-powered atmospheric water harvesting devices which are under development, along with design criteria, finding they could help a billion people to access safe drinking water, albeit such off-the-grid generation may sometimes "undermine efforts to develop permanent piped infrastructure" among other problems.[25][26][27]
The total quantity of water available at any given time is an important consideration. Some human water users have an intermittent need for water. For example, many farms require large quantities of water in the spring, and no water at all in the winter. Other users have a continuous need for water, such as a power plant that requires water for cooling. Over the long term the average rate of precipitation within a watershed is the upper bound for average consumption of natural surface water from that watershed.
Irrigation (also referred to as watering of plants) is the practice of applying controlled amounts of watertoland to help grow crops, landscape plants, and lawns. Irrigation has been a key aspect of agriculture for over 5,000 years and has been developed by many cultures around the world. Irrigation helps to grow crops, maintain landscapes, and revegetate disturbed soils in dry areas and during times of below-average rainfall. In addition to these uses, irrigation is also employed to protect crops from frost,[28] suppress weed growth in grain fields, and prevent soil consolidation. It is also used to cool livestock, reduce dust, dispose of sewage, and support mining operations. Drainage, which involves the removal of surface and sub-surface water from a given location, is often studied in conjunction with irrigation.
There are several methods of irrigation that differ in how water is supplied to plants. Surface irrigation, also known as gravity irrigation, is the oldest form of irrigation and has been in use for thousands of years. In sprinkler irrigation, water is piped to one or more central locations within the field and distributed by overhead high-pressure water devices. Micro-irrigation is a system that distributes water under low pressure through a piped network and applies it as a small discharge to each plant. Micro-irrigation uses less pressure and water flow than sprinkler irrigation. Drip irrigation delivers water directly to the root zone of plants. Subirrigation has been used in field crops in areas with high water tables for many years. It involves artificially raising the water table to moisten the soil below the root zone of plants.
Irrigation water can come from groundwater (extracted from springs or by using wells), from surface water (withdrawn from rivers, lakesorreservoirs) or from non-conventional sources like treated wastewater, desalinated water, drainage water, or fog collection. Irrigation can be supplementary to rainfall, which is common in many parts of the world as rainfed agriculture, or it can be full irrigation, where crops rarely rely on any contribution from rainfall. Full irrigation is less common and only occurs in arid landscapes with very low rainfall or when crops are grown in semi-arid areas outside of rainy seasons.It is estimated that 22% of worldwide water is used in industry.[29] Major industrial users include hydroelectric dams, thermoelectric power plants, which use water for cooling, ore and oil refineries, which use water in chemical processes, and manufacturing plants, which use water as a solvent. Water withdrawal can be very high for certain industries, but consumption is generally much lower than that of agriculture.
Water is used in renewable power generation. Hydroelectric power derives energy from the force of water flowing downhill, driving a turbine connected to a generator. This hydroelectricity is a low-cost, non-polluting, renewable energy source. Significantly, hydroelectric power can also be used for load following unlike most renewable energy sources which are intermittent. Ultimately, the energy in a hydroelectric power plant is supplied by the sun. Heat from the sun evaporates water, which condenses as rain in higher altitudes and flows downhill. Pumped-storage hydroelectric plants also exist, which use grid electricity to pump water uphill when demand is low, and use the stored water to produce electricity when demand is high.
Thermoelectric power plants using cooling towers have high consumption, nearly equal to their withdrawal, as most of the withdrawn water is evaporated as part of the cooling process. The withdrawal, however, is lower than in once-through cooling systems.
Water is also used in many large scale industrial processes, such as thermoelectric power production, oil refining, fertilizer production and other chemical plant use, and natural gas extraction from shale rock. Discharge of untreated water from industrial uses is pollution. Pollution includes discharged solutes and increased water temperature (thermal pollution).
It is estimated that 8% of worldwide water use is for domestic purposes.[29] These include drinking water, bathing, cooking, toilet flushing, cleaning, laundry and gardening. Basic domestic water requirements have been estimated by Peter Gleick at around 50 liters per person per day, excluding water for gardens.
Drinking water is water that is of sufficiently high quality so that it can be consumed or used without risk of immediate or long term harm. Such water is commonly called potable water. In most developed countries, the water supplied to domestic, commerce and industry is all of drinking water standard even though only a very small proportion is actually consumed or used in food preparation.
844 million people still lacked even a basic drinking water service in 2017.[30]: 3 Of those, 159 million people worldwide drink water directly from surface water sources, such as lakes and streams.[30]: 3 One in eight people in the world do not have access to safe water.[31][32]
The world's supply of groundwater is steadily decreasing. Groundwater depletion (oroverdrafting) is occurring for example in Asia, South America and North America. It is still unclear how much natural renewal balances this usage, and whether ecosystems are threatened.[49]
Water resource management is the activity of planning, developing, distributing and managing the optimum use of water resources. It is an aspect of water cycle management. The field of water resources management will have to continue to adapt to the current and future issues facing the allocation of water. With the growing uncertainties of global climate change and the long-term impacts of past management actions, this decision-making will be even more difficult. It is likely that ongoing climate change will lead to situations that have not been encountered. As a result, alternative management strategies, including participatory approaches and adaptive capacity are increasingly being used to strengthen water decision-making.
Ideally, water resource management planning has regard to all the competing demands for water and seeks to allocate water on an equitable basis to satisfy all uses and demands. As with other resource management, this is rarely possible in practice so decision-makers must prioritise issues of sustainability, equity and factor optimisation (in that order!) to achieve acceptable outcomes. One of the biggest concerns for water-based resources in the future is the sustainability of the current and future water resource allocation.
Sustainable Development Goal 6 has a target related to water resources management: "Target 6.5: By 2030, implement integrated water resources management at all levels, including through transboundary cooperation as appropriate."[51][52]
At present, only about 0.08 percent of all the world's fresh water is accessible. And there is ever-increasing demand for drinking, manufacturing, leisure and agriculture. Due to the small percentage of water available, optimizing the fresh water we have left from natural resources has been a growing challenge around the world.
Much effort in water resource management is directed at optimizing the use of water and in minimizing the environmental impact of water use on the natural environment. The observation of water as an integral part of the ecosystem is based on integrated water resources management, based on the 1992 Dublin Principles (see below).
Sustainable water management requires a holistic approach based on the principles of Integrated Water Resource Management, originally articulated in 1992 at the Dublin (January) and Rio (July) conferences. The four Dublin Principles, promulgated in the Dublin Statement are:
Implementation of these principles has guided reform of national water management law around the world since 1992.
Further challenges to sustainable and equitable water resources management include the fact that many water bodies are shared across boundaries which may be international (see water conflict) or intra-national (see Murray-Darling basin).
Integrated water resources management (IWRM) has been defined by the Global Water Partnership (GWP) as "a process which promotes the coordinated development and management of water, land and related resources, in order to maximize the resultant economic and social welfare in an equitable manner without compromising the sustainability of vital ecosystems".[53]
Some scholars say that IWRM is complementary to water security because water security is a goal or destination, whilst IWRM is the process necessary to achieve that goal.[54]
IWRM is a paradigm that emerged at international conferences in the late 1900s and early 2000s, although participatory water management institutions have existed for centuries.[55] Discussions on a holistic way of managing water resources began already in the 1950s leading up to the 1977 United Nations Water Conference.[56] The development of IWRM was particularly recommended in the final statement of the ministers at the International Conference on Water and the Environment in 1992, known as the Dublin Statement. This concept aims to promote changes in practices which are considered fundamental to improved water resource management. IWRM was a topic of the second World Water Forum, which was attended by a more varied group of stakeholders than the preceding conferences and contributed to the creation of the GWP.[55]
In the International Water Association definition, IWRM rests upon three principles that together act as the overall framework:[57]
In 2002, the development of IWRM was discussed at the World Summit on Sustainable Development held in Johannesburg, which aimed to encourage the implementation of IWRM at a global level.[58] The third World Water Forum recommended IWRM and discussed information sharing, stakeholder participation, and gender and class dynamics.[55]
Operationally, IWRM approaches involve applying knowledge from various disciplines as well as the insights from diverse stakeholders to devise and implement efficient, equitable and sustainable solutions to water and development problems. As such, IWRM is a comprehensive, participatory planning and implementation tool for managing and developing water resources in a way that balances social and economic needs, and that ensures the protection of ecosystems for future generations. In addition, in light of contributing the achievement of Sustainable Development goals (SDGs),[59] IWRM has been evolving into more sustainable approach as it considers the Nexus approach, which is a cross-sectoral water resource management. The Nexus approach is based on the recognition that "water, energy and food are closely linked through global and local water, carbon and energy cycles or chains."
An IWRM approach aims at avoiding a fragmented approach of water resources management by considering the following aspects: Enabling environment, roles of Institutions, management Instruments. Some of the cross-cutting conditions that are also important to consider when implementing IWRM are: Political will and commitment, capacity development, adequate investment, financial stability and sustainable cost recovery, monitoring and evaluation. There is not one correct administrative model. The art of IWRM lies in selecting, adjusting and applying the right mix of these tools for a given situation. IWRM practices depend on context; at the operational level, the challenge is to translate the agreed principles into concrete action.
Integrated urban water management (IUWM) is the practice of managing freshwater, wastewater, and storm water as components of a basin-wide management plan. It builds on existing water supply and sanitation considerations within an urban settlement by incorporating urban water management within the scope of the entire river basin.[60] IUWM is commonly seen as a strategy for achieving the goals of Water Sensitive Urban Design. IUWM seeks to change the impact of urban development on the natural water cycle, based on the premise that by managing the urban water cycle as a whole; a more efficient use of resources can be achieved providing not only economic benefits but also improved social and environmental outcomes. One approach is to establish an inner, urban, water cycle loop through the implementation of reuse strategies. Developing this urban water cycle loop requires an understanding both of the natural, pre-development, water balance and the post-development water balance. Accounting for flows in the pre- and post-development systems is an important step toward limiting urban impacts on the natural water cycle.[61]
Water resource management and governance is handled differently by different countries. For example, in the United States, the United States Geological Survey (USGS) and its partners monitor water resources, conduct research and inform the public about groundwater quality.[64] Water resources in specific countries are described below:
Water resources by country
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