Water

Agriculture is by far the largest consumer of the earth‘s available freshwater. Irrigation accounts for the greatest agricultural water usage. Nowadays, agriculture already competes with environmental needs and peoples’ everyday use, particularly in the areas where irrigation is essential.
In some regions of the world, water scarcity has already become an acute problem. The situation will deteriorate dramatically in years to come, if we continue to overuse, waste and contaminate the resources available at local and regional levels.
The IAASTD report shows that the global water supply is sufficient to produce food for a growing and more demanding world population. However, if today’s water management practices continue, they could result in acute water crises in several parts of the world. It is therefore necessary to integrate our water usage into the natural hydrological cycle. Moreover, we need water management systems which take all users of a watershed into account. "First, already more than a billion people live in river basins characterized by physical water scarcity. In these areas water availability is a major constraint to agriculture. (...) More areas will face seasonal or permanent shortages. Second, competition for water between sectors will inten­sify. (...) In most countries water for cities receives priority over wa­ter for agriculture by law or de facto, leaving less water for agriculture, particularly near large cities in water-short areas, such as Middle East and North Africa, Central Asia, India, Pakistan, Mexico, and northern China. Water for en­ergy, i.e., hydropower and crop production for biofuels, will further add to the pressure on water resources. Third, signs of severe environmental degradation because of water scar­city, overabstraction and water pollution are apparent in a growing number of places with often severe consequenc­es for the poor who depend heavily on ecosystems for their livelihoods." (Global, p. 341)

Green and blue water

The water in rivers and lakes, groundwater and glacial water reserves are called "blue water". This blue water only makes up one part of the earth’s freshwater supply.
The majority of rainfall on the earth's surface evaporates. It either evaporates directly as "non-beneficial evaporation" or, after aiding plant growth, as "productive transpiration". This type of rainwater is termed "green water".
Around 1,800 cubic kilometres of the water used in agriculture worldwide stems from blue water resources. 5,000 cubic kilometres are made up of "green water". The proportion of "green water“ varies between 55% and 80%, depending on the region of the world, as well as the local wood density. "In many water scarce areas current per capita water consumption is  unsustainable. Globally, water is sufficient to produce food for a grow­ing and wealthier population, but continuance with today's water management practices will lead to many acute water crises in many parts of the world." (Global, p. 279)

Competition for a scarce resource

The biggest opportunity and challenge for future water management is to maximise the huge potential of "green water". Methods of storing "green water" in soil and plants, as well as storing it as "blue water", have to be improved. For this purpose, there are several methods of "water harvesting”: One approach is to avoid water evaporation directly from the soil and increase the water storage capacity of soil and vegetation (Global, p. 39).>>more

Facts & Figures

Between 1990 and 2012, over 2.3 billion people gained access to improved water sources and 2 billion to improved sanitation facilities. However, by the end of 2012, over 748 million people - 90% living in sub-Saharan Africa and Asia - were still without access to improved sources of drinking water, 82% of them in rural areas. 2.5 billion people still use unimproved sanitation facilities.

Contaminated water can transmit diseases such diarrhoea, cholera, dysentery, typhoid and polio. Contaminated drinking-water is estimated to cause more than 500 000 diarrhoeal deaths each year.

A combination of rising global population, economic growth and climate change means that 5 billion (52%) of the world’s projected 9.7 billion people will live in areas where fresh water supply is under pressure by 2050. Researchers expect about 1 billion more people to be living in areas where water demand exceeds surface-water supply.

69% of the world’s freshwater withdrawals are committed to agriculture. The industrial sector accounts for 19% while only 12% of water withdrawals are destined for households and municipal use.

Future global agricultural water consumption (including both rainfed and irrigated agriculture) is estimated to increase by about 19% to 8,515 cubic kilometres per year in 2050.

Every day for more than 20 years, an average of 2,000 hectares of irrigated land in arid and semi-arid areas across 75 countries have been degraded by salt. Today about 62 million hectares are affected - 20% of the world's irrigated lands - up from 45 million hectares in the early 1990s.

Anthropogenic inputs of excess nutrients into the coastal environment, from agricultural activities and wastewater, have dramatically increased the occurrence of coastal eutrophication and hypoxia. Worldwide there are now more than 500 ‘dead zones’ covering 250,000 km2 with the number doubling every ten years since the 1960s.

Agriculture is a significant water user in Europe, accounting for around 33% of total water use. This share varies markedly, however, and can reach up to 80% in parts of southern Europe, where irrigation of crops accounts for virtually all agricultural water use.

According to the OECD Environmental Outlook to 2050, global water demand will increase by 55% due to growing demand from manufacturing (+400%), thermal power plants (+140%) and domestic use (+130%). These competing demands will put water use by farmers at risk. 2.3 billion more people than today - 40% of the global population - will be living in river basins under severe water stress.

Irrigation provides approximately 40% of the world’s food, from an estimated 20% of agricultural land, or about 300 million hectares globally. Almost half of the total area being irrigated worldwide is located in Pakistan, China and India, and covers 80, 35 and 34% of the cultivated area respectively.

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Videos: Water

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Spot: Why is water so important to our food security?

Graphics

  • UNEP Access to safe waterUNEP Access to safe water
  • UNEP Irrigated cropland by regionUNEP Irrigated cropland by region
  • UNEP Water for food production 1960-2050UNEP Water for food production 1960-2050
  • UNEP Water scarcity indexUNEP Water scarcity index
  • Climate change and water scarcityClimate change and water scarcity
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Unterstützer von www.weltagrarbericht.de biovision Verlag der Arbeitsgemeinschaft bäuerliche Landwirtschaft e.V. Demeter Greenpeace Forum Umwelt und Entwicklung Eine Welt Stiftung Die Grünen, Europäische Freie Allianz Evangelischer Entwicklungsdienst NABU - Naturschutzbund Deutschland e.V. Misereor Deutsche Gesellschaft für internationale Zusammenarbeit Zukunftsstiftung Landwirtschaft in der GLS Treuhand Zukunftsstiftung Landwirtschaft in der GLS Treuhand
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