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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}}
'''Water resources
[[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]].]]▼
▲'''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]]. Artificial sources of fresh water can include treated wastewater ([[reclaimed water|wastewater reuse]]) and [[desalination|desalinated seawater]]. Human uses of water resources include [[agriculture|agricultural]], [[Industry (economics)|industrial]], [[household]], [[recreation]]al and [[natural environment|environmental]] 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|renewable resource.]]
{{TOC limit|3}}
== Natural sources of fresh water ==
{{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]].
=== 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.
Natural surface water can be augmented by importing surface water from another watershed through a [[canal]] or [[Pipeline transport|pipeline]].
[[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 ==
=== Wastewater reuse ===
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==== Air-capture over oceans ====
[[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:
▲* 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>]]
▲[[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" />]]
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 ==
[[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
===
{{
{{excerpt|Irrigation|paragraphs=1-3}}
===
{{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.
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.
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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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>
== Challenges and threats ==
▲=== Water scarcity ===
{{excerpt|Water scarcity|paragraphs=1|file=no}}
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{{Further|Effects of climate change on the water cycle}}
{{excerpt|Water security#Climate change|paragraphs=1|file=no}}<!-- this takes the first two paragraphs of the lead of the sub-article -->
=== Groundwater overdrafting ===
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>
{{excerpt|overdrafting|paragraphs=1}}
== Water resource management ==
{{Further|Water resources law|}}
▲[[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]].]]
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 [[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.
[[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.
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).
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>
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" />
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>
# 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]].
# Economic efficiency: bringing the greatest benefit to the greatest number of users possible with the available financial and water resources.
# Ecological sustainability: requiring that [[aquatic ecosystem]]s are acknowledged as users and that adequate allocation is made to sustain their natural functioning.
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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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."
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.
=== Managing water in urban settings ===
[[File:Urban Water Cycle - EPA 2004.png|thumb|Typical urban water cycle depicting drinking [[water purification]] and municipal [[sewage treatment]] systems]]▼
{{Excerpt|Integrated urban water management|paragraphs=1-2|file=no}}
▲[[File:Urban Water Cycle - EPA 2004.png|thumb|Typical urban water cycle depicting drinking [[water purification]] and municipal [[sewage treatment]] systems]]
==By country==
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