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| − | Water scarcity is defined as the gap between the available supply and the expressed demand of freshwater in a specified domain, under prevailing institutional arrangements (including both resource ‘pricing’ and retail charging arrangements) and infrastructural conditions (FAO, 2012 forthcoming).
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| + | Water scarcity is defined as the gap between the available supply and the expressed demand of freshwater in a specified domain, under prevailing institutional arrangements (including both resource ‘pricing’ and retail charging arrangements) and infrastructural conditions.<ref name="FAO2012">FAO (2012): Water scarcity and food security. A framework for action. To be published.</ref> |
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| − | = Introduction = | + | = Introduction = |
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| − | '''Water scarcity = an excess of water demand over available supply''' | + | '''Water scarcity = an excess of water demand over available supply''' |
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| + | Scarcity is signaled by unsatisfied demand, tensions between users, competition for water, over- extraction of groundwater and insufficient flows to the natural environment. |
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| − | Scarcity is signaled by unsatisfied demand, tensions between users, competition for water, over- extraction of groundwater and insufficient flows to the natural environment.
| + | Water scarcity is caused by a wide-ranging combination of factors, all which are related to human interference with the water cycle. Water scarcity is fundamentally dynamic: its level can vary within a given time frame as a result of natural hydrological variability, but even more so due to prevailing economic policy, planning and management approaches, and the varying capacity of societies to anticipate changing levels of supply or demand. Scarcity can result from short-sighted policies, such as the over-allocation of water use licenses in a river basin, or from the excessive expansion of irrigation areas with free or low-cost water for farmers. The problem intensifies with increasing demand by users and/or with the decreasing availability and quality of the resource. Scarcity can arises in close juxtaposition with water plenty if there is no legal or institutional arrangement in place to improve access, or if the required infrastructure does not exist or is not feasible. When identified correctly, many causes of scarcity can be predicted, avoided and/or mitigated. |
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| − | Water scarcity is caused by a wide-ranging combination of factors, all which are related to human interference with the water cycle. Water scarcity is fundamentally dynamic: its level can vary within a given time frame as a result of natural hydrological variability, but even more so due to prevailing economic policy, planning and management approaches, and the varying capacity of societies to anticipate changing levels of supply or demand. Scarcity can result from short-sighted policies, such as the over-allocation of water use licenses in a river basin, or from the excessive expansion of irrigation areas with free or low-cost water for farmers. The problem intensifies with increasing demand by users and/or with the decreasing availability and quality of the resource. Scarcity can arises in close juxtaposition with water plenty if there is no legal or institutional arrangement in place to improve access, or if the required infrastructure does not exist or is not feasible. When identified correctly, many causes of scarcity can be predicted, avoided and/or mitigated. <br>
| + | = Related terms = |
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| − | = <br>Related terms =
| + | '''Water shortage''': a shortage of water supply of an acceptable quality; low levels of water supply at a given place and a given time relative to design supply levels as a result of insufficient water resources, lack of infrastructure or poorly maintained infrastructure; low levels of water resources as a result of annual or seasonal differences in climate or a range of hydrological or hydro-geological factors. Water shortage is an absolute, not a relative, concept. |
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| − | '''Water shortage''': a shortage of water supply of an acceptable quality; low levels of water supply at a given place and a given time relative to design supply levels as a result of insufficient water resources, lack of infrastructure or poorly maintained infrastructure; low levels of water resources as a result of annual or seasonal differences in climate or a range of hydrological or hydro-geological factors. Water shortage is an absolute, not a relative, concept. | + | '''Water stress''': the symptoms of water scarcity or shortage: e.g. growing conflict between users and competition for water, declining standards of reliability and service, harvest failures and food insecurity. |
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| − | '''Water stress''': the symptoms of water scarcity or shortage: e.g. growing conflict between users and competition for water, declining standards of reliability and service, harvest failures and food insecurity.
| + | = Dimensions of water scarcity = |
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| − | <br>
| + | The causes of scarcity, as indicated in the chosen definition, may be of a varying nature, with each requiring a specific response. FAO proposes three main dimensions of water scarcity that can be summarized as follows: |
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| − | = Dimensions of water scarcity =
| + | (i) scarcity in '''availability '''of water of acceptable quality with respect to aggregated demand, in the simple case of physical water shortage; |
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| − | <br>The causes of scarcity, as indicated in the chosen definition, may be of a varying nature, with each requiring a specific response. FAO proposes three main dimensions of water scarcity that can be summarized as follows:
| + | (ii) scarcity due to the '''lack of adequate infrastructure''', irrespective of the level of water resources, because of financial , technical or other constraints; and |
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| − | (i) scarcity in '''availability '''of water of acceptable quality with respect to aggregated demand, in the simple case of physical water shortage; | + | (iii) scarcity in '''access to water services '''because of the failure of institutions (including legal rights) in place to ensure reliable, secure and equitable supply of water to users. This dimension relates to the organizational and accountability dimensions proposed by the World Bank (2007).<ref name="WB">World Bank (2007): Making the Most of Scarcity: Accountability for Better Water Management Results in the Middle East and North Africa. Washington, USA.</ref> |
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| − | (ii) scarcity due to the '''lack of adequate infrastructure''', irrespective of the level of water resources, because of financial , technical or other constraints; and
| + | = Indicators of water scarcity = |
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| − | (iii) scarcity in '''access to water services '''because of the failure of institutions (including legal rights) in place to ensure reliable, secure and equitable supply of water to users. This dimension relates to the organizational and accountability dimensions proposed by the World Bank (2007). | + | The best-known indicator of national water scarcity is per capita renewable water, with threshold values of 500, 1.000 and 1.700 m³/person/year used to distinguish between different levels of water stress .<ref name="Falkenmark">Falkenmark, M & Widstrand, C. (1992): Population and Water Resources: A delicate balance, Population 41 Bulletin, Washington: Population Reference Bureau.</ref><ref name="UN2006">UN-Water (2006): Coping with water scarcity: A strategic issue and priority for system-wide action. |
| | + | http://waterwiki.net/images/9/92/UN_Water_-_waterscarcity_leaflet.pdf</ref> Following this criterion, countries or regions are considered to be facing <u>absolute water scarcity </u>if renewable water resources are < 500 m³ per capita; <u>chronic water shortage </u>if renewable water resources are between 500 and 1000 m³ per capita; and <u>regular water stress </u>between 1.000 and 1.700 m³ per capita (Table 1). This crude approach to measuring water scarcity is primarily based on estimates of the number of people who can live reasonably with a certain unit of water resources.<ref name="Falkenmark1984">Falkenmark, M. (1984): New ecological approach to the water cycle: ticket to the future. AMBIO.</ref> This indicator is widely used as it can be easily calculated for every year and every country in the world, based on water resources data<ref name="FAO-Aquastat">FAO-AQUASTAT (2012): FAO Global information system on water and agriculture. http://www.fao.org/nr/water/aquastat/maps/index.stm</ref> and available population data<ref>United Nations (UN) (2009): United Nations Population Information network online database. |
| | + | http://www.un.org/popin/ (cited November 2009).</ref>. Furthermore, population projections, available until 2100, allow for projections of water scarcity levels in the forthcoming decades. |
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| − | = Indicators of water scarcity =
| + | {| align="center" style="width: 486px; height: 140px;" border="1" cellspacing="1" cellpadding="1" |
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| − | <br>The best-known indicator of national water scarcity is per capita renewable water, with threshold values of 500, 1.000 and 1.700 m³/person/year used to distinguish between different levels of water stress (Falkenmark and Widstrand, 1992, UN-Water, 2006b). Following this criterion, countries or regions are considered to be facing <u>absolute water scarcity </u>if renewable water resources are < 500 m³ per capita; <u>chronic water shortage </u>if renewable water resources are between 500 and 1000 m³ per capita; and <u>regular water stress </u>between 1.000 and 1.700 m³ per capita (Table 1). This crude approach to measuring water scarcity is primarily based on estimates of the number of people who can live reasonably with a certain unit of water resources (Falkenmark, 1984). This indicator is widely used as it can be easily calculated for every year and every country in the world, based on water resources data (FAO-AQUASTAT, 2012) and available population data (UN, 2009). Furthermore, population projections, available until 2100, allow for projections of water scarcity levels in the forthcoming decades. <br>
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| − | {| style="width: 486px; height: 140px" cellspacing="1" cellpadding="1" width="486" align="center" border="1" | + | |
| − | |+ '''Table 1: Conventional definitions of levels of water stress (after Falkenmark and Widstrand, 1992)'''
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| − | ! scope="col" | '''Annual renewable freshwater (m³/pers.yr)''' | + | ! scope="col" | '''Annual renewable freshwater (m³/pers.yr)''' |
| | ! scope="col" | '''Level of water stress''' | | ! scope="col" | '''Level of water stress''' |
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| − | | < 500 | + | | < 500 |
| | | Absolute water scarcity | | | Absolute water scarcity |
| | |- | | |- |
| − | | 500 – 1.000 | + | | 500 – 1.000 |
| | | Chronic water shortage | | | Chronic water shortage |
| | |- | | |- |
| − | | 1.000 – 1.700 | + | | 1.000 – 1.700 |
| | | Regular water stress | | | Regular water stress |
| | |- | | |- |
| − | | > 1.700 | + | | > 1.700 |
| | | Occasional or local water stress | | | Occasional or local water stress |
| | |} | | |} |
| | + | <p style="text-align: center;">Table 1: Conventional definitions of levels of water stress (after Falkenmark and Widstrand, 1992)</p> |
| | + | In arid and semi-arid regions, water is an even more essential factor for agriculture and food production. IPCC assessments predict (IPCC, 2007) that in most of these regions climate change will further acerbate the water scarcity due to changed rainfall patterns and/or reduced rainfall.<ref name="IPCC">Intergovernmental Panel on Climate Change (IPCC) (2007): Climate Change 2007: Synthesis Report. |
| | + | http://www.ipcc.ch/publications_and_data/ar4/syr/en/spms3.html |
| | + | </ref> It is estimated that 14 % more freshwater will have to be withdrawn for agricultural use in the next 30 years.<ref name="UN2006">UN-Water (2006): Coping with water scarcity: A strategic issue and priority for system-wide action. http://waterwiki.net/images/9/92/UN_Water_-_waterscarcity_leaflet.pdf</ref> This underscores how urgent the need is for a more efficient and productive water use. |
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| + | = References = |
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| − | In arid and semi-arid regions, water is an even more essential factor for agriculture and food production. IPCC assessments predict (IPCC, 2007) that in most of these regions climate change will further acerbate the water scarcity due to changed rainfall patterns and/or reduced rainfall. It is estimated that 14 % more freshwater will have to be withdrawn for agricultural use in the next 30 years (UN, 2006). This underscores how urgent the need is for a more efficient and productive water use.<br>
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| − | = Links = | + | |
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| − | http://www.un.org/waterforlifedecade/scarcity.shtml<br>http://www.unep.org/dewa/vitalwater/jpg/0221-waterstress-EN.jpg<br>http://www.ipcc.ch/publications_and_data/ar4/syr/en/spms3.html<br>http://www.ipcc.ch/publications_and_data/ar4/syr/en/spms3.html
| + | <references /> |
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| − | <br>
| + | = Links = |
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| − | = Literature =
| + | [http://www.un.org/waterforlifedecade/scarcity.shtml http://www.un.org/waterforlifedecade/scarcity.shtml]<br/>[http://www.unep.org/dewa/vitalwater/jpg/0221-waterstress-EN.jpg http://www.unep.org/dewa/vitalwater/jpg/0221-waterstress-EN.jpg]<br/>[http://www.ipcc.ch/publications_and_data/ar4/syr/en/spms3.html http://www.ipcc.ch/publications_and_data/ar4/syr/en/spms3.html]<br/>[http://www.ipcc.ch/publications_and_data/ar4/syr/en/spms3.html http://www.ipcc.ch/publications_and_data/ar4/syr/en/spms3.html] |
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| − | Falkenmark, M & Widstrand, C. 1992. Population and Water Resources: A delicate balance, Population 41 Bulletin, Washington: Population Reference Bureau.<br>Falkenmark, M. 1984. New ecological approach to the water cycle: ticket to the future. AMBIO 13(3)<br>FAO, 2012: Water scarcity and food security. A framework for action. To be published.<br>FAO-AQUASTAT. 2009. FAO Global information system on water and agriculture. 16 http://www.fao.org/nr/water/aquastat/maps/index.stm<br>United Nations (UN). 2009. United Nations Population Information network online database. 4 http://www.un.org/popin/ (cited November 2009).<br>UN-Water. 2006b. Coping with water scarcity: A strategic issue and priority for system-wide action. 11 http://waterwiki.net/images/9/92/UN_Water_-_waterscarcity_leaflet.pdf. <br>World Bank. 2007. Making the Most of Scarcity: Accountability for Better Water Management Results in the Middle East and North Africa. Washington, USA<br>
| + | <br/> |
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| − | | + | Falkenmark, M & Widstrand, C. 1992. Population and Water Resources: A delicate balance, Population 41 Bulletin, Washington: Population Reference Bureau.<br/>Falkenmark, M. 1984. New ecological approach to the water cycle: ticket to the future. AMBIO 13(3)<br/>FAO, 2012: Water scarcity and food security. A framework for action. To be published.<br/>FAO-AQUASTAT. 2009. FAO Global information system on water and agriculture. 16 [http://www.fao.org/nr/water/aquastat/maps/index.stm http://www.fao.org/nr/water/aquastat/maps/index.stm]<br/>United Nations (UN). 2009. United Nations Population Information network online database. 4 [http://www.un.org/popin/ http://www.un.org/popin/] (cited November 2009).<br/>UN-Water. 2006b. Coping with water scarcity: A strategic issue and priority for system-wide action. 11 [http://waterwiki.net/images/9/92/UN_Water_-_waterscarcity_leaflet.pdf http://waterwiki.net/images/9/92/UN_Water_-_waterscarcity_leaflet.pdf].<br/>World Bank. 2007. Making the Most of Scarcity: Accountability for Better Water Management Results in the Middle East and North Africa. Washington, USA |
Water scarcity is defined as the gap between the available supply and the expressed demand of freshwater in a specified domain, under prevailing institutional arrangements (including both resource ‘pricing’ and retail charging arrangements) and infrastructural conditions.[1]
Scarcity is signaled by unsatisfied demand, tensions between users, competition for water, over- extraction of groundwater and insufficient flows to the natural environment.
Water scarcity is caused by a wide-ranging combination of factors, all which are related to human interference with the water cycle. Water scarcity is fundamentally dynamic: its level can vary within a given time frame as a result of natural hydrological variability, but even more so due to prevailing economic policy, planning and management approaches, and the varying capacity of societies to anticipate changing levels of supply or demand. Scarcity can result from short-sighted policies, such as the over-allocation of water use licenses in a river basin, or from the excessive expansion of irrigation areas with free or low-cost water for farmers. The problem intensifies with increasing demand by users and/or with the decreasing availability and quality of the resource. Scarcity can arises in close juxtaposition with water plenty if there is no legal or institutional arrangement in place to improve access, or if the required infrastructure does not exist or is not feasible. When identified correctly, many causes of scarcity can be predicted, avoided and/or mitigated.
The causes of scarcity, as indicated in the chosen definition, may be of a varying nature, with each requiring a specific response. FAO proposes three main dimensions of water scarcity that can be summarized as follows:
The best-known indicator of national water scarcity is per capita renewable water, with threshold values of 500, 1.000 and 1.700 m³/person/year used to distinguish between different levels of water stress .[3][4] Following this criterion, countries or regions are considered to be facing absolute water scarcity if renewable water resources are < 500 m³ per capita; chronic water shortage if renewable water resources are between 500 and 1000 m³ per capita; and regular water stress between 1.000 and 1.700 m³ per capita (Table 1). This crude approach to measuring water scarcity is primarily based on estimates of the number of people who can live reasonably with a certain unit of water resources.[5] This indicator is widely used as it can be easily calculated for every year and every country in the world, based on water resources data[6] and available population data[7]. Furthermore, population projections, available until 2100, allow for projections of water scarcity levels in the forthcoming decades.
Table 1: Conventional definitions of levels of water stress (after Falkenmark and Widstrand, 1992)
In arid and semi-arid regions, water is an even more essential factor for agriculture and food production. IPCC assessments predict (IPCC, 2007) that in most of these regions climate change will further acerbate the water scarcity due to changed rainfall patterns and/or reduced rainfall.[8] It is estimated that 14 % more freshwater will have to be withdrawn for agricultural use in the next 30 years.[4] This underscores how urgent the need is for a more efficient and productive water use.
Falkenmark, M & Widstrand, C. 1992. Population and Water Resources: A delicate balance, Population 41 Bulletin, Washington: Population Reference Bureau.
Falkenmark, M. 1984. New ecological approach to the water cycle: ticket to the future. AMBIO 13(3)
FAO, 2012: Water scarcity and food security. A framework for action. To be published.
FAO-AQUASTAT. 2009. FAO Global information system on water and agriculture. 16 http://www.fao.org/nr/water/aquastat/maps/index.stm
United Nations (UN). 2009. United Nations Population Information network online database. 4 http://www.un.org/popin/ (cited November 2009).
UN-Water. 2006b. Coping with water scarcity: A strategic issue and priority for system-wide action. 11 http://waterwiki.net/images/9/92/UN_Water_-_waterscarcity_leaflet.pdf.
World Bank. 2007. Making the Most of Scarcity: Accountability for Better Water Management Results in the Middle East and North Africa. Washington, USA
