Water availability

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The term water availability , which UNESCO speaks of available freshwater resources , describes the amount of freshwater that is available to a person per year. Depending on the size of this amount, the subordinate terms water scarcity , water shortage and water emergency are defined , right up to the water crisis . The provision and subsequent storage and distribution is known as water management .

Around the world, around 4 billion people or two thirds of the world's population do not have sufficient water available for at least one month a year , so they suffer from severe water scarcity. 1.8 to 2.9 billion people suffer from severe water scarcity for 4 to 6 months a year, approx. 0.5 billion people all year round.

Freshwater resources worldwide

Development of fresh water supplies according to "World Scientists' Warning to Humanity: A Second Notice" 2017

Of the approximately 1.6 billion cubic kilometers of water that is on planet Earth , 35 million cubic kilometers (2.5%) are fresh water. Only about 213 thousand cubic kilometers of it are relatively easily accessible to humans, especially in lakes, rivers and in the around 45,000 large dams around the world . The rest is in the form of glaciers , snow , ice , groundwater , ground ice , permafrost, soil moisture and swamp water , so it is not easily accessible. To calculate the water availability, UNESCO uses the total amount of fresh water, regardless of its accessibility.

The availability of water depends on other factors, such as rain and other precipitation , which fall unevenly over time and region, and the water quality , which can be strongly negatively influenced by environmental influences.

ETH calculations

The water research institute of the Eidgenössische Technische Hochschule Zürich uses these principles to calculate the water availability in Switzerland with 6520 cubic meters per person per year in 1990 , in Algeria with 770 cubic meters and in Saudi Arabia with 160 cubic meters of fresh water, whereby water quantities below 1700 cubic meters are considered water scarcity , below 1000 cubic meters referred to as a lack of water and below 500 cubic meters as a water emergency .

UNESCO calculations

The comparison of the continental proportions of the world population compared to the proportions of the global availability of freshwater, which was published by UNESCO in 2003, provides further information on water availability. This results in the following table:

continent x% water availability at x% of the world population
Asia 36 61
South America 26th 7th
North and Central America 16 8th
Africa 11 13
Europe 8th 13
Australia and Oceania 5 <1

This overview shows in particular the pollution of Asia and Europe, where the share of the world population is significantly higher than the share of global water availability. However, the situation in Africa is particularly dramatic, as the water infrastructure here is extremely poor.


In November 2009, leading agricultural economists from all over Europe issued a declaration in which they called for a clear focus on European common goods - in particular for climate protection , biodiversity and water management ("A Common Agricultural Policy for European Public Goods").

The EU is reforming its common agricultural policy - see agricultural subsidies after 2012 .

Forecast 2025/2050

On the basis of this table and the fact that water consumption has increased sixfold between 1930 and 2002 due to a tripling of the world population while doubling the average water consumption per capita, UNESCO predicts a dramatic decline in water availability by 2025 and beyond. This prognosis is based on the continuously increasing water consumption, caused both by global economic growth and the spread of consumption-intensive lifestyles in so-called third countries . Since the increasing abstraction from freshwater resources inevitably goes hand in hand with an increasing discharge of wastewater , UNESCO estimates assume global wastewater production of around 1,500 cubic kilometers in 2050 and an associated wastewater pollution of up to 12,000 cubic kilometers worldwide, since it is assumed that one liter Wastewater contaminated eight liters of fresh water.

In 2002, Mark W. Rosegrant used three model scenarios to show possible solutions to cope with the forecast reduction in water availability by 2025 . In the business-as-usual scenario, only a slight increase in investments in water-saving technologies is assumed with a cautious improvement in water management , which leads to a crisis scenario ( see also water crisis ) and is terminated by a sustainable scenario with regard to worldwide efforts to use water more effectively becomes. Further approaches will take place for the first time from 24.-25. The international conference IWRM in Karlsruhe, which will take place in November 2010, aims to bring together the global knowledge on the subject of water management.

Web links


Individual evidence

  1. ^ Mesfin M. Mekonnen, Arjen Y. Hoekstra: Four billion people facing severe water scarcity . In: Science . 2016, doi : 10.1126 / sciadv.1500323 .
  2. William J. Ripple, Christopher Wolf, Thomas M. Newsome, Mauro Galetti, Mohammed Alamgir, Eileen Crist, Mahmoud I. Mahmoud, William F. Laurance and 15,364 life scientists from 184 countries: World Scientists' Warning to Humanity: A Second Notice . In: BioScience . tape 67 , no. 12 , 2017, p. 1026-1028 , doi : 10.1093 / biosci / bix125 .
  3. a b Federal Agency for Political Education
  4. ^ Eawag, Water Research Institute at ETH Zurich ( Memento from June 27, 2010 in the Internet Archive )
  5. ^ The United Nations World Water Development Report 1, 2003
  6. Declaration "A Common Agricultural Policy for European Public Goods" download . Reformthecap.eu. November 18, 2009. Retrieved June 6, 2010.
  7. Mark W. Rosegrant et al. a., World Water and Food to 2025: Dealing with Scarcity, Washington, DC 2002
  8. BMBF Integrated Water Resource Management ( Memento of the original from October 11, 2010 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. @1@ 2Template: Webachiv / IABot / www.bmbf.wasserressourcen-management.de