![World Water Footprint](https://upload.wikimedia.org/wikipedia/commons/d/d0/World_Water_Footprint.png)
A water footprint shows the extent of water use in relation to
consumption by people.
The water footprint of an individual, community, or business is defined as the total volume of
fresh water
Fresh water or freshwater is any naturally occurring liquid or frozen water containing low concentrations of dissolved salts and other total dissolved solids. Although the term specifically excludes seawater and brackish water, it does include ...
used to produce the goods and services consumed by the individual or community or produced by the business. Water use is measured in water volume consumed (
evaporated) and/or polluted per unit of time. A water footprint can be calculated for any well-defined group of
consumer
A consumer is a person or a group who intends to order, or uses purchased goods, products, or services primarily for personal, social, family, household and similar needs, who is not directly related to entrepreneurial or business activities. T ...
s (e.g., an individual, family, village, city, province, state, or nation) or
producers (e.g., a public organization, private enterprise, or economic sector), for a single
process
A process is a series or set of activities that interact to produce a result; it may occur once-only or be recurrent or periodic.
Things called a process include:
Business and management
*Business process, activities that produce a specific se ...
(such as growing rice) or for any
product or
service
Service may refer to:
Activities
* Administrative service, a required part of the workload of university faculty
* Civil service, the body of employees of a government
* Community service, volunteer service for the benefit of a community or a pu ...
.
Traditionally, water use has been approached from the production side, by quantifying the following three columns of water use: water withdrawals in the
agricultural
Agriculture or farming is the practice of cultivating Plant, plants and livestock. Agriculture was the key development in the rise of Sedentism, sedentary human civilization, whereby farming of Domestication, domesticated species created food ...
,
industrial
Industrial may refer to:
Industry
* Industrial archaeology, the study of the history of the industry
* Industrial engineering, engineering dealing with the optimization of complex industrial processes or systems
* Industrial city, a city dominate ...
, and
domestic
Domestic may refer to:
In the home
* Anything relating to the human home or family
** A domestic animal, one that has undergone domestication
** A domestic appliance, or home appliance
** A domestic partnership
** Domestic science, sometimes cal ...
sector. While this does provide valuable data, it is a limited way of looking at water use in a
globalised
Globalization, or globalisation (Commonwealth English; see spelling differences), is the process of interaction and integration among people, companies, and governments worldwide. The term ''globalization'' first appeared in the early 20t ...
world, in which products are not always consumed in their country of origin. International trade of agricultural and industrial products in effect creates a global flow of
virtual water, or ''embodied water'' (akin to the concept of
embodied energy).
In 2002, the water footprint concept was introduced in order to have a consumption-based
indicator
Indicator may refer to:
Biology
* Environmental indicator of environmental health (pressures, conditions and responses)
* Ecological indicator of ecosystem health (ecological processes)
* Health indicator, which is used to describe the health o ...
of water use, that could provide useful information in addition to the traditional production-sector-based indicators of water use. It is analogous to the
ecological footprint
The ecological footprint is a method promoted by the Global Footprint Network to measure human demand on natural capital, i.e. the quantity of nature it takes to support people or an economy. It tracks this demand through an ecological accounti ...
concept introduced in the 1990s. The water footprint is a geographically explicit indicator, not only showing volumes of water use and pollution, but also the locations. Thus, it gives a grasp on how economic choices and processes influence the availability of adequate water resources and other ecological realities across the globe (and vice versa).
Definition and measures
There are many different aspects to water footprint and therefore different definitions and measures to describe them. Blue water footprint refers to groundwater or surface water usage, green water footprint refers to rainwater, and grey water footprint refers to the amount of water needed to dilute pollutants.
Blue water footprint
A ''blue water footprint'' refers to the volume of water that has been sourced from
surface or
groundwater
Groundwater is the water present beneath Earth's surface in rock and soil pore spaces and in the fractures of rock formations. About 30 percent of all readily available freshwater in the world is groundwater. A unit of rock or an unconsolidate ...
resources (lakes, rivers, wetlands and
aquifer
An aquifer is an underground layer of water-bearing, permeable rock, rock fractures, or unconsolidated materials (gravel, sand, or silt). Groundwater from aquifers can be extracted using a water well. Aquifers vary greatly in their characterist ...
s) and has either evaporated (for example while
irrigating crops), or been incorporated into a product or taken from one body of water and returned to another, or returned at a different time. Irrigated agriculture, industry and domestic water use can each have a blue water footprint.
Green water footprint
A ''green water footprint'' refers to the amount of water from
precipitation
In meteorology, precipitation is any product of the condensation of atmospheric water vapor that falls under gravitational pull from clouds. The main forms of precipitation include drizzle, rain, sleet, snow, ice pellets, graupel and hail. ...
that, after having been stored in the root zone of the soil (green water), is either lost by
evapotranspiration
Evapotranspiration (ET) is the combined processes by which water moves from the earth’s surface into the atmosphere. It covers both water evaporation (movement of water to the air directly from soil, canopies, and water bodies) and transpi ...
or incorporated by plants. It is particularly relevant for agricultural,
horticultural
Horticulture is the branch of agriculture that deals with the art, science, technology, and business of plant cultivation. It includes the cultivation of fruits, vegetables, nuts, seeds, herbs, sprouts, mushrooms, algae, flowers, seaweeds and no ...
and
forestry
Forestry is the science and craft of creating, managing, planting, using, conserving and repairing forests, woodlands, and associated resources for human and environmental benefits. Forestry is practiced in plantations and natural stands. Th ...
products.
Grey water footprint
A ''grey water footprint'' refers to the volume of water that is required to dilute
pollutants (industrial discharges, seepage from tailing ponds at mining operations, untreated municipal wastewater, or
nonpoint source pollution
Nonpoint source (NPS) pollution refers to diffuse contamination (or pollution) of water or air that does not originate from a single discrete source. This type of pollution is often the cumulative effect of small amounts of contaminants gathered ...
such as agricultural runoff or
urban runoff
Urban runoff is surface runoff of rainwater, landscape irrigation, and car washing created by urbanization. Impervious surfaces (roads, parking lots and sidewalks) are constructed during land development. During rain , storms and other precipit ...
) to such an extent that the quality of the water meets agreed water quality standards.
It is calculated as:
:
where ''L'' is the
pollutant load (as
mass flux
In physics and engineering, mass flux is the rate of mass flow. Its SI units are kg m−2 s−1. The common symbols are ''j'', ''J'', ''q'', ''Q'', ''φ'', or Φ (Greek lower or capital Phi), sometimes with subscript ''m'' to indicate mass is the ...
), ''c''
max the maximum allowable concentration and ''c''
nat the natural concentration of the pollutant in the receiving water body (both expressed in mass/volume).
Calculation for different actors
The water footprint of a process is expressed as
volumetric flow rate
In physics and engineering, in particular fluid dynamics, the volumetric flow rate (also known as volume flow rate, or volume velocity) is the volume of fluid which passes per unit time; usually it is represented by the symbol (sometimes ). I ...
of water. That of a product is the whole footprint (sum) of processes in its complete supply chain divided by the number of product units. For consumers, businesses and geographic area, water footprint is indicated as volume of water per time, in particular:
* That of a consumer is the sum of footprint of all consumed products.
* That of a community or a nation is the sum for all of its members resp. inhabitants.
* That of a business is the footprint of all produced goods.
* That of a geographically delineated area is the footprint of all processes undertaken in this area. The virtual change in water of an area is the net import of virtual water ''V
i, net'', defined as the difference of the gross import ''V
i'' of virtual water from its gross export ''V
e''. The water footprint of national consumption ''WF
area,nat'' results from this as the sum of the water footprint of national area and its virtual change in water.
History
The concept of a ''water footprint'' was coined in 2002, by
Arjen Hoekstra
Arjen Hoekstra (June 28, 1967 - November 18, 2019) was a professor at the University of Twente who pioneered the concept of the water footprint - a way of measuring the extent of water consumption. His work drew attention to the hidden water use a ...
, Professor in
water management
Water resources are natural resources of water that are potentially useful for humans, for example as a source of drinking water supply or irrigation water. 97% of the water on the Earth is salt water and only three percent is fresh water; slightl ...
at the
University of Twente
The University of Twente (Dutch: ''Universiteit Twente''; , abbr. ) is a public technical university located in Enschede, Netherlands.
The university has been placed in the top 170 universities in the world by multiple central ranking tables. ...
,
Netherlands
)
, anthem = ( en, "William of Nassau")
, image_map =
, map_caption =
, subdivision_type = Sovereign state
, subdivision_name = Kingdom of the Netherlands
, established_title = Before independence
, established_date = Spanish Netherl ...
, and co-founder and scientific director of the Water Footprint Network, whilst working at the
UNESCO-IHE
IHE Delft Institute for Water Education is the largest international graduate water education facility in the world and is based in Delft, Netherlands. Delft is a world renowned knowledge centre on water infrastructure, technology and sciences, an ...
Institute for Water Education, as a
metric
Metric or metrical may refer to:
* Metric system, an internationally adopted decimal system of measurement
* An adjective indicating relation to measurement in general, or a noun describing a specific type of measurement
Mathematics
In mathema ...
to measure the amount of water consumed and polluted to produce goods and services along their full supply chain.
Water footprint is one of a family of
ecological footprint
The ecological footprint is a method promoted by the Global Footprint Network to measure human demand on natural capital, i.e. the quantity of nature it takes to support people or an economy. It tracks this demand through an ecological accounti ...
indicators, which also includes
carbon footprint
A carbon footprint is the total greenhouse gas (GHG) emissions caused by an individual, event, organization, service, place or product, expressed as carbon dioxide equivalent (CO2e). Greenhouse gases, including the carbon-containing gases carbo ...
and
land footprint. The water footprint concept is further related to the idea of
virtual water trade introduced in the early 1990s by Professor
John Allan (2008
Stockholm Water Prize Laureate). The most elaborate publications on how to estimate water footprints are a 2004 report on the ''Water footprint of nations'' from UNESCO-IHE, the 2008 book ''Globalization of Water'', and the 2011 manual ''The water footprint assessment manual: Setting the global standard''.
Cooperation between global leading institutions in the field has led to the establishment of the Water Footprint Network in 2008.
Water Footprint Network (WFN)
The Water Footprint Network is an international learning community (a
non-profit foundation under
Dutch law) which serves as a platform for sharing knowledge, tools and innovations among governments, businesses and communities concerned about growing
water scarcity
Water scarcity (closely related to water stress or water crisis) is the lack of fresh water Water resources, resources to meet the standard water demand. There are two types of water scarcity: physical or economic water scarcity. Physical water ...
and increasing
water pollution
Water pollution (or aquatic pollution) is the contamination of water bodies, usually as a result of human activities, so that it negatively affects its uses. Water bodies include lakes, rivers, oceans, aquifers, reservoirs and groundwater. Water ...
levels, and their impacts on people and nature. The network consists of around 100 partners from all sectors – producers, investors, suppliers and regulators – as well as
non-governmental organisations and
academics. It describes its mission as follows:
To provide science-based, practical solutions and strategic insights that empower companies, governments, individuals and small-scale producers to transform the way we use and share fresh water within earth's limits.
International standard
In February 2011, the Water Footprint Network, in a global collaborative effort of environmental organizations, companies, research institutions and the UN, launched the ''Global Water Footprint Standard''. In July 2014, the
International Organization for Standardization
The International Organization for Standardization (ISO ) is an international standard development organization composed of representatives from the national standards organizations of member countries. Membership requirements are given in Ar ...
issued ''ISO 14046:2014, Environmental management—Water footprint—Principles, requirements and guidelines'', to provide practical guidance to practitioners from various backgrounds, such as large companies, public authorities, non-governmental organizations, academic and research groups as well as small and medium enterprises, for carrying out a water footprint assessment. The ISO standard is based on
life-cycle assessment
Life cycle assessment or LCA (also known as life cycle analysis) is a methodology for assessing environmental impacts associated with all the stages of the Product lifecycle, life cycle of a commercial product, Process lifecycle, process, or ...
(LCA) principles and can be applied for different sorts of assessment of products and companies.
Life-cycle assessment of water use
Life-cycle assessment
Life cycle assessment or LCA (also known as life cycle analysis) is a methodology for assessing environmental impacts associated with all the stages of the Product lifecycle, life cycle of a commercial product, Process lifecycle, process, or ...
(LCA) is a systematic, phased approach to assessing the environmental aspects and potential impacts that are associated with a product, process or service. "Life cycle" refers to the major activities connected with the product's life-span, from its manufacture, use, and maintenance, to its final disposal, and also including the acquisition of
raw material
A raw material, also known as a feedstock, unprocessed material, or primary commodity, is a basic material that is used to produce goods, finished goods, energy, or intermediate materials that are feedstock for future finished products. As feedst ...
required to manufacture the product. Thus a method for assessing the environmental impacts of freshwater consumption was developed. It specifically looks at the damage to three areas of protection: human health, ecosystem quality, and resources. The consideration of water consumption is crucial where water-intensive products (for example agricultural goods) are concerned that need to therefore undergo a life-cycle assessment. In addition, regional assessments are equally as necessary as the impact of water use depends on its location. In short, LCA is important as it identifies the impact of water use in certain products, consumers, companies, nations, etc. which can help reduce the amount of water used.
Water availability
Globally, about 4 percent of
precipitation
In meteorology, precipitation is any product of the condensation of atmospheric water vapor that falls under gravitational pull from clouds. The main forms of precipitation include drizzle, rain, sleet, snow, ice pellets, graupel and hail. ...
falling on land each year (about ), is used by rain-fed agriculture and about half is subject to evaporation and transpiration in
forest
A forest is an area of land dominated by trees. Hundreds of definitions of forest are used throughout the world, incorporating factors such as tree density, tree height, land use, legal standing, and ecological function. The United Nations' ...
s and other natural or quasi-natural landscapes. The remainder, which goes to
groundwater
Groundwater is the water present beneath Earth's surface in rock and soil pore spaces and in the fractures of rock formations. About 30 percent of all readily available freshwater in the world is groundwater. A unit of rock or an unconsolidate ...
replenishment and
surface runoff
Surface runoff (also known as overland flow) is the flow of water occurring on the ground surface when excess rainwater, stormwater, meltwater, or other sources, can no longer sufficiently rapidly infiltrate in the soil. This can occur when th ...
, is sometimes called "total actual renewable freshwater resources". Its magnitude was in 2012 estimated at /year.
[Frenken, K. and V. Gillet. 2012. ]Irrigation
Irrigation (also referred to as watering) is the practice of applying controlled amounts of water to land to help grow Crop, crops, Landscape plant, landscape plants, and Lawn, lawns. Irrigation has been a key aspect of agriculture for over 5,00 ...
water requirement and water withdrawal by country. AQUASTAT, FAO. It represents water that can be used either in-stream or after withdrawal from surface and groundwater sources. Of this remainder, about were withdrawn in 2007, of which , or 69 percent, were used by agriculture, and , or 19 percent, by other industry. Most agricultural use of withdrawn water is for
irrigation
Irrigation (also referred to as watering) is the practice of applying controlled amounts of water to land to help grow Crop, crops, Landscape plant, landscape plants, and Lawn, lawns. Irrigation has been a key aspect of agriculture for over 5,00 ...
, which uses about 5.1 percent of total actual renewable
freshwater
Fresh water or freshwater is any naturally occurring liquid or frozen water containing low concentrations of dissolved salts and other total dissolved solids. Although the term specifically excludes seawater and brackish water, it does include ...
resources.
[ World water use has been growing rapidly in the last hundred years.
]
Water footprint of products (agricultural sector)
The water footprint of a product is the total volume of freshwater used to produce the product, summed over the various steps of the production chain. The water footprint of a product refers not only to the total volume of water used; it also refers to where and when the water is used. The Water Footprint Network maintains a global database on the water footprint of products: WaterStat. Nearly over 70% of the water supply worldwide is used in the agricultural sector.
The water footprints involved in various diets vary greatly, and much of the variation tends to be associated with levels of meat consumption. The following table gives examples of estimated global average water footprints of popular agricultural products.[Mekonnen, M. M. and A. Y. Hoekstra. 2010. The green, blue and grey water footprint of farm animals and animal products. Volume 1: Main report. UNESCO-IHE., Institute for Water Education. 50 pp.]
(For more product water footprints: see th
Product Gallery of the Water Footprint Network
Water footprint of companies (industrial sector)
The water footprint of a business, the 'corporate water footprint', is defined as the total volume of freshwater that is used directly or indirectly to run and support a business. It is the total volume of water use to be associated with the use of the business outputs. The water footprint of a business consists of water used for producing/manufacturing or for supporting activities and the indirect water use in the producer's supply chain.
The Carbon Trust argue that a more robust approach is for businesses to go beyond simple volumetric measurement to assess the full range of water impact from all sites. Its work with leading global pharmaceutical company GlaxoSmithKline
GSK plc, formerly GlaxoSmithKline plc, is a British multinational pharmaceutical and biotechnology company with global headquarters in London, England. Established in 2000 by a merger of Glaxo Wellcome and SmithKline Beecham. GSK is the ten ...
(GSK) analysed four key categories: water availability, water quality, health impacts, and licence to operate (including reputational and regulatory risks) in order to enable GSK to quantitatively measure, and credibly reduce, its year-on-year water impact.
The Coca-Cola Company operates over a thousand manufacturing plants in about 200 countries. Making its drink uses a lot of water. Critics say its water footprint has been large. Coca-Cola has started to look at its water sustainability
Specific definitions of sustainability are difficult to agree on and have varied in the literature and over time. The concept of sustainability can be used to guide decisions at the global, national, and individual levels (e.g. sustainable livi ...
. It has now set out goals to reduce its water footprint such as treating the water it uses so it goes back into the environment in a clean state. Another goal is to find sustainable sources for the raw materials it uses in its drinks, such as sugarcane
Sugarcane or sugar cane is a species of (often hybrid) tall, Perennial plant, perennial grass (in the genus ''Saccharum'', tribe Andropogoneae) that is used for sugar Sugar industry, production. The plants are 2–6 m (6–20 ft) tall with ...
, oranges
An orange is a fruit of various citrus species in the family Rutaceae (see list of plants known as orange); it primarily refers to ''Citrus'' × ''sinensis'', which is also called sweet orange, to distinguish it from the related ''Citrus × ...
, and corn
Maize ( ; ''Zea mays'' subsp. ''mays'', from es, maíz after tnq, mahiz), also known as corn (North American and Australian English), is a cereal grain first domesticated by indigenous peoples in southern Mexico about 10,000 years ago. Th ...
. By making its water footprint better, the company can reduce costs, improve the environment, and benefit the communities in which it operates.
Water footprint of individual consumers (domestic sector)
The water footprint of an individual refers to the sum of their direct and indirect freshwater use. The direct water use is the water used at home, while the indirect water use relates to the total volume of freshwater that is used to produce the goods and services consumed.
The average global water footprint of an individual is 1,385 m3 per year. Residents of some example nations have water footprints as shown in the table:
Water footprint of nations
The water footprint of a nation is the amount of water used to produce the goods and services consumed by the inhabitants of that nation. Analysis of the water footprint of nations illustrates the global dimension of water consumption and pollution, by showing that several countries rely heavily on foreign water resources and that (consumption patterns in) many countries significantly and in various ways impact how, and how much, water is being consumed and polluted elsewhere on Earth. International water dependencies are substantial and are likely to increase with continued global trade liberalisation
Free trade is a trade policy that does not restrict imports or exports. It can also be understood as the free market idea applied to international trade. In government, free trade is predominantly advocated by political parties that hold econo ...
. The largest share (76%) of the virtual water flows between countries is related to international trade in crops and derived crop products. Trade in animal products and industrial products contributed 12% each to the global virtual water flows. The four major direct factors determining the water footprint of a country are: volume of consumption (related to the gross national income); consumption pattern (e.g. high versus low meat consumption
Meat is animal flesh that is eaten as food. Humans have hunted, farmed, and scavenged animals for meat since prehistoric times. The establishment of settlements in the Neolithic Revolution allowed the domestication of animals such as chick ...
); climate (growth conditions); and agricultural practice (water use efficiency).
Production or consumption
The assessment of total water use in connection to consumption can be approached from both ends of the supply chain
In commerce, a supply chain is a network of facilities that procure raw materials, transform them into intermediate goods and then final products to customers through a distribution system. It refers to the network of organizations, people, acti ...
. The water footprint of production estimates how much water from local sources is used or polluted in order to provide the goods and services produced in that country. The water footprint of consumption of a country looks at the amount of water used or polluted (locally, or in the case of imported goods, in other countries) in connection with all the goods and services that are consumed by the inhabitants of that country. The water footprint of production and that of consumption, can also be estimated for any administrative unit such as a city, province, river basin or the entire world.
Absolute or per capita
The absolute water footprint is the total sum of water footprints of all people. A country's per capita water footprint (that nation's water footprint divided by its number of inhabitants) can be used to compare its water footprint with those of other nations.
The global water footprint in the period 1996–2005 was 9.087 Gm3/yr (Billion Cubic Metres per year, or 9.087.000.000.000.000 liters/year), of which 74% was and green, 11% blue, 15% grey. This is an average amount per capita of 1.385 Gm3/yr., or 3.800 liters per person per day. On average 92% of this is embedded in agricultural products consumed, 4.4% in industrial products consumed, and 3.6% is domestic water use. The global water footprint related to producing goods for export is 1.762 Gm3/y.
In absolute terms, India is the country with the largest water footprint in the world, a total of 987 Gm3/yr. In relative terms (i.e. taking population size into account), the people of the USA have the largest water footprint, with 2480 m3/yr per capita, followed by the people in south European countries such as Greece, Italy and Spain (2300–2400 m3/yr per capita). High water footprints can also be found in Malaysia and Thailand. In contrast, the Chinese people have a relatively low per capita water footprint with an average of 700 m3/yr. (These numbers are also from the period 1996-2005.)
Internal or external
The internal water footprint is the amount of water used from domestic water resources; the external water footprint is the amount of water used in other countries to produce goods and services imported and consumed by the inhabitants of the country. When assessing the water footprint of a nation, it is crucial to take into account the international flows of virtual water (also called ''embodied water'', i.e. the water used or polluted in connection to all agricultural and industrial commodities) leaving and entering the country. When taking the use of domestic water resources as a starting point for calculating a nation's water footprint, one should subtract the virtual water flows that leave the country and add the virtual water flows that enter the country.
The external part of a nation's water footprint varies strongly from country to country. Some African nations, such as Sudan, Mali, Nigeria, Ethiopia, Malawi and Chad have hardly any external water footprint, simply because they have little import. Some European countries on the other hand—e.g. Italy, Germany, the UK and the Netherlands—have external water footprints that constitute 50–80% of their total water footprint. The agricultural products that on average contribute most to the external water footprints of nations are: bovine meat, soybean, wheat, cocoa, rice, cotton and maize.
The top 10 gross virtual water exporting nations, which together account for more than half of the global virtual water export, are the United States (314 Gm3/year), China (143 Gm3/year), India (125 Gm3/year), Brazil (112 Gm3/year), Argentina (98 Gm3/year), Canada (91 Gm3/year), Australia (89 Gm3/year), Indonesia (72 Gm3/year), France (65 Gm3/year), and Germany (64 Gm3/year).
The top 10 gross virtual water importing nations are the United States (234 Gm3/year), Japan (127 Gm3/year), Germany (125 Gm3/year), China (121 Gm3/year), Italy (101 Gm3/year), Mexico (92 Gm3/year), France (78 Gm3/year), the United Kingdom (77 Gm3/year), and The Netherlands (71 Gm3/year).
Water use in continents
Europe
Each EU citizen
European Union citizenship is afforded to all citizens of member states of the European Union (EU). It was formally created with the adoption of the 1992 Maastricht Treaty, at the same time as the creation of the EU. EU citizenship is additio ...
consumes 4,815 litres of water per day on average; 44% is used in power production primarily to cool thermal plants or nuclear power
Nuclear power is the use of nuclear reactions to produce electricity. Nuclear power can be obtained from nuclear fission, nuclear decay and nuclear fusion reactions. Presently, the vast majority of electricity from nuclear power is produced b ...
plants. Energy production annual water consumption in the EU 27 in 2011 was, in billion m3: for gas 0.53, coal 1.54 and nuclear 2.44. Wind energy avoided the use of 387 million cubic metres (mn m3) of water in 2012, avoiding a cost of €743 million.
Asia
In south India the state Tamil Nadu is one of the main agricultural producers in India and it relies largely in groundwater for irrigation. In ten years, from 2002 to 2012, the Gravity Recovery and Climate Experiment calculated that the groundwater reduced in 1.4 m yr−1, which "is nearly 8% more than the annual recharge rate."
Environmental water use
Although agriculture's water use includes provision of important terrestrial environmental values (as discussed in the " Water footprint of products" section above), and much "green water" is used in maintaining forests and wild lands, there is also direct environmental use (e.g. of surface water) that may be allocated by governments. For example, in California
California is a U.S. state, state in the Western United States, located along the West Coast of the United States, Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the List of states and territori ...
, where water use issues are sometimes severe because of drought, about 48 percent of "dedicated water use" in an average water year is for the environment (somewhat more than for agriculture). Such environmental water use is for keeping streams flowing, maintaining aquatic and riparian habitats, keeping wetlands wet, etc.
Criticism
Insufficient consideration of consequences of proposed water saving policies to farm households
According to Dennis Wichelns of the International Water Management Institute
The International Water Management Institute (IWMI) is a non-profit international water management research organisation under the CGIAR with its headquarters in Colombo, Sri Lanka, and offices across Africa and Asia. Research at the Institute foc ...
: "Although one goal of virtual water analysis is to describe opportunities for improving water security, there is almost no mention of the potential impacts of the prescriptions arising from that analysis on farm households in industrialized or developing countries. It is essential to consider more carefully the inherent flaws in the virtual water and water footprint perspectives, particularly when seeking guidance regarding policy decisions."
Regional water scarcity should be taken into account when interpreting water footprint
The application and interpretation of water footprints may sometimes be used to promote industrial activities that lead to facile criticism of certain products. For example, the 140 litres required for coffee production for one cup might be of no harm to water resources if its cultivation occurs mainly in humid areas, but could be damaging in more arid regions. Other factors such as hydrology, climate, geology, topography, population and demographics should also be taken into account. Nevertheless, high water footprint calculations do suggest that environmental concern may be appropriate.
Many of the criticisms, including the above ones, compare the description of the water footprint of a water system
A water supply network or water supply system is a system of engineered hydrologic and hydraulic components that provide water supply. A water supply system typically includes the following:
# A drainage basin (see water purification – source ...
to generated impacts, which is about its performance. Such a comparison between descriptive and performance factors and indicators is basically flawed.
The use of the term ''footprint'' can also confuse people familiar with the notion of a carbon footprint
A carbon footprint is the total greenhouse gas (GHG) emissions caused by an individual, event, organization, service, place or product, expressed as carbon dioxide equivalent (CO2e). Greenhouse gases, including the carbon-containing gases carbo ...
, because the water footprint concept includes sums of water quantities without necessarily evaluating related impacts. This is in contrast to the carbon footprint, where carbon emissions are not simply summarized but normalized by CO2 emissions, which are globally identical, to account for the environmental harm. The difference is due to the somewhat more complex nature of water; while involved in the global hydrological cycle, it is expressed in conditions both local and regional through various forms like river basins, watersheds, on down to groundwater (as part of larger aquifer
An aquifer is an underground layer of water-bearing, permeable rock, rock fractures, or unconsolidated materials (gravel, sand, or silt). Groundwater from aquifers can be extracted using a water well. Aquifers vary greatly in their characterist ...
systems). Furthermore, looking at the definition of the footprint itself, and comparing ecological footprint
The ecological footprint is a method promoted by the Global Footprint Network to measure human demand on natural capital, i.e. the quantity of nature it takes to support people or an economy. It tracks this demand through an ecological accounti ...
, carbon footprint
A carbon footprint is the total greenhouse gas (GHG) emissions caused by an individual, event, organization, service, place or product, expressed as carbon dioxide equivalent (CO2e). Greenhouse gases, including the carbon-containing gases carbo ...
and water footprint, we realize that the three terms are indeed legitimate.
Sustainable water use
Sustainable
Specific definitions of sustainability are difficult to agree on and have varied in the literature and over time. The concept of sustainability can be used to guide decisions at the global, national, and individual levels (e.g. sustainable livin ...
water use involves the rigorous assessment of all source of clean water to establish the current and future rates of use, the impacts of that use both downstream and in the wider area where the water may be used and the impact of contaminated water streams on the environment and economic well being of the area. It also involves the implementation of social policies
Social policy is a plan or action of government or institutional agencies which aim to improve or reform society.
Some professionals and universities consider social policy a subset of public policy, while other practitioners characterize soci ...
such as water pricing in order to manage water demand. In some localities, water may also have spiritual relevance and the use of such water may need to take account of such interests. For example, the Maori believe that water is the source and foundation of all life and have many spiritual associations with water and places associated with water. On a national and global scale, water sustainability requires strategic and long term planning to ensure appropriate sources of clean water are identified and the environmental and economic impact of such choices are understood and accepted. The re-use and reclamation of water is also part of sustainability including downstream impacts on both surface waters and ground waters.
Sustainability assessment
Water footprint accounting has advanced substantially in recent years, however, water footprint analysis also needs sustainability assessment as its last phase. One of the developments is to employ sustainable efficiency and equity ("Sefficiency in Sequity"), which present a comprehensive approach to assessing the sustainable use of water.
Sectoral distributions of withdrawn water use
Several nations estimate sectoral distribution of use of water withdrawn from surface and groundwater sources. For example, in Canada, in 2005, 42 billion m3 of withdrawn water were used, of which about 38 billion m3 were freshwater. Distribution of this use among sectors was: thermoelectric power generation 66.2%, manufacturing 13.6%, residential 9.0%, agriculture 4.7%, commercial and institutional 2.7%, water treatment and distribution systems 2.3%, mining 1.1%, and oil and gas extraction 0.5%. The 38 billion m3 of freshwater withdrawn in that year can be compared with the nation's annual freshwater yield (estimated as streamflow) of 3,472 billion m3. Sectoral distribution is different in many respects in the US, where agriculture accounts for about 39% of fresh water withdrawals, thermoelectric power generation 38%, industrial 4%, residential 1%, and mining (including oil and gas) 1%.[
Within the agricultural sector, withdrawn water use is for irrigation and for livestock. Whereas all irrigation in the US (including loss in conveyance of irrigation water) is estimated to account for about 38 percent of US withdrawn freshwater use,][Maupin, M. A. et al. 2014. Estimated use of water in the United States 2010. U. S. Geological Survey Circular 1405. 55 pp.] the irrigation water used for production of livestock feed and forage has been estimated to account for about 9 percent, and other withdrawn freshwater use for the livestock sector (for drinking, washdown of facilities, etc.) is estimated at about 0.7 percent.[ Because agriculture is a major user of withdrawn water, changes in the magnitude and efficiency of its water use are important. In the US, from 1980 (when agriculture's withdrawn water use peaked) to 2010, there was a 23 percent reduction in agriculture's use of withdrawn water,][ while US agricultural output increased by 49 percent over that period.
In the US, irrigation water application data are collected in the quinquennial Farm and Ranch Irrigation Survey, conducted as part of the Census of Agriculture. Such data indicate great differences in irrigation water use within various agricultural sectors. For example, about 14 percent of corn-for-grain land and 11 percent of soybean land in the US are irrigated, compared with 66 percent of vegetable land, 79 percent of orchard land and 97 percent of rice land.][US Department of Agriculture. 2009. 2007 Census of agriculture. Farm and ranch irrigation survey (2008). Volume 3. Special Studies. Part 1. AC-07-SS-1. 177 pp. + appendices.][USDA. 2009. 2007 Census of agriculture. United States summary and State Data. Vol. 1. Geographic Area Series. Part 51. AC-07-A-51. 639 pp. + appendices.]
See also
References
External links
Water Footprint Network
Personal Water Footprint Calculator
{{DEFAULTSORT:Water Footprint
Water
Water resources management
Water and the environment
Environmental terminology
Macroeconomic indicators
Economic globalization
Environmental indices