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 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 consumers (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 (such as growing rice) or for any product or service.
Traditionally, water use has been approached from the production side, by quantifying the following three columns of water use: water withdrawals in the agricultural, industrial, and domestic sector. While this does provide valuable data, it is a limited way of looking at water use in a globalised 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 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 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).
A blue water footprint is the volume of water that has been sourced from surface or groundwater resources (lakes, rivers, wetlands and aquifers) 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.
A green water footprint is the amount of water from precipitation that, after having been stored in the root zone of the soil (green water), is either lost by evapotranspiration or incorporated by plants. It is particularly relevant for agricultural, horticultural and forestry products.
A grey water footprint is 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 such as agricultural runoff or urban runoff) 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), cmax the maximum allowable concentration and cnat the natural concentration of the pollutant in the receiving water body (both expressed in mass/volume).
The water footprint of a process is expressed as volumetric flow rate 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:
The concept of a water footprint was coined in 2002, by Arjen Hoekstra, Professor in water management at the University of Twente, Netherlands, and co-founder and scientific director of the Water Footprint Network, whilst working at the UNESCO-IHE Institute for Water Education, as a metric 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 indicators, which also includes carbon footprint 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.
The Water Footprint Network is an international learning community (non-profit foundation under Dutch law) that serves as a platform for sharing knowledge, tools and innovations among governments, businesses and communities that are concerned about growing water scarcity and increasing water pollution 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 academia. 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.
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 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 (LCA) principles and can be applied for different sorts of assessment of products and companies.
Life-cycle assessment (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 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.
Globally, about 4 percent of precipitation falling on land each year (about 117,000 km3 (28,000 cu mi)), is used by rain-fed agriculture and about half is subject to evaporation and transpiration in forests and other natural or quasi-natural landscapes. The remainder, which goes to groundwater replenishment and surface runoff, is sometimes called “total actual renewable freshwater resources”. Its magnitude was in 2012 estimated at 52,579 km3 (12,614 cu mi)/year. It represents water that can be used either in-stream or after withdrawal from surface and groundwater sources. Of this remainder, about 3,918 km3 (940 cu mi) were withdrawn in 2007, of which 2,722 km3 (653 cu mi), or 69 percent, were used by agriculture, and 734 km3 (176 cu mi), or 19 percent, by other industry. Most agricultural use of withdrawn water is for irrigation, which uses about 5.1 percent of total actual renewable freshwater resources. World water use has been growing rapidly in the last hundred years (see graph from New Scientist article ).
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.
|Product||Global average water footprint, L/kg|
(For more product water footprints: see the Product Gallery of the Water Footprint Network)
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) 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.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, oranges, and corn. By making its water footprint better, the company can reduce costs, improve the environment, and benefit the communities in which it operates.
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:
|Nation||annual water footprint|
|United Kingdom||1,695 m3|
|United States||2,842 m3|
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. 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); climate (growth conditions); and agricultural practice (water use efficiency).
The assessment of total water use in connection to consumption can be approached from both ends of the supply chain.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.
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)
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).
Each EU citizen consumes 4,815 litres of water per day on average; 44% is used in power production primarily to cool thermal plants or nuclear power 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.
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."
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, 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.
According to Dennis Wichelns of the International Water Management Institute: "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."
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.
The use of the term footprint can also confuse people familiar with the notion of a carbon footprint, 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 systems).
Sustainable 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 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.
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 cu.m of freshwater withdrawn in that year can be compared with the nation's annual freshwater yield (estimated as streamflow) of 3,472 billion cu.m.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,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.
Resource depletion is the consumption of a resource faster than it can be replenished. Natural resources are commonly divided between renewable resources and non-renewable resources. Use of either of these forms of resources beyond their rate of replacement is considered to be resource depletion. The value of a resource is a direct result of its availability in nature and the cost of extracting the resource, the more a resource is depleted the more the value of the resource increases. There are several types of resource depletion, the most known being: Aquifer depletion, deforestation, mining for fossil fuels and minerals, pollution or contamination of resources, slash-and-burn agricultural practices, Soil erosion, and overconsumption, excessive or unnecessary use of resources.
The virtual water trade, a concept introduced by Tony Allan, is the hidden flow of water if food or other commodities are traded from one place to another. For instance, it takes 1,340 cubic meters of water to produce one metric tonne of wheat. The precise volume can be more or less depending on climatic conditions and agricultural practice. Hoekstra have defined the virtual-water content of a product as "the volume of freshwater used to produce the product, measured at the place where the product was actually produced". It refers to the sum of the water use in the various steps of the production chain.
Environmental degradation is the deterioration of the environment through depletion of resources such as air, water and soil; the destruction of ecosystems; habitat destruction; the extinction of wildlife; and pollution. It is defined as any change or disturbance to the environment perceived to be deleterious or undesirable. As indicated by the I=PAT equation, environmental impact (I) or degradation is caused by the combination of an already very large and increasing human population (P), continually increasing economic growth or per capita affluence (A), and the application of resource-depleting and polluting technology (T).
Reclaimed or recycled water is the process of converting wastewater into water that can be reused for other purposes. Reuse may include irrigation of gardens and agricultural fields or replenishing surface water and groundwater. Reused water may also be directed toward fulfilling certain needs in residences, businesses, and industry, and could even be treated to reach drinking water standards. This last option is called either "direct potable reuse" or "indirect potable" reuse, depending on the approach used.
Human impact on the environment or anthropogenic impact on the environment includes changes to biophysical environments and ecosystems, biodiversity, and natural resources caused directly or indirectly by humans, including global warming, environmental degradation, mass extinction and biodiversity loss, ecological crisis, and ecological collapse. Modifying the environment to fit the needs of society is causing severe effects, which become worse as the problem of human overpopulation continues. Some human activities that cause damage to the environment on a global scale include population growth, overconsumption, overexploitation, pollution, and deforestation, to name but a few. Some of the problems, including global warming and biodiversity loss pose an existential risk to the human race, and human overpopulation causes those problems.
Water resource management is the activity of planning, developing, distributing and managing the optimum use of water resources. It is a sub-set of water cycle management.
Environmental vegetarianism is the practice of vegetarianism when motivated by the desire to create a sustainable diet that avoids the negative environmental impact of meat production. Livestock as a whole is estimated to be responsible for around 18% of global greenhouse gas emissions. As a result, significant reduction in meat consumption has been advocated by, among others, the Intergovernmental Panel on Climate Change in their 2019 special report and as part of the 2017 World Scientists' Warning to Humanity.
Water scarcity is the lack of fresh water resources to meet water demand. It affects every continent and was listed in 2019 by the World Economic Forum as one of the largest global risks in terms of potential impact over the next decade. It is manifested by partial or no satisfaction of expressed demand, economic competition for water quantity or quality, disputes between users, irreversible depletion of groundwater, and negative impacts on the environment. Two-thirds of the global population live under conditions of severe water scarcity at least 1 month of the year. Half a billion people in the world face severe water scarcity all year round. Half of the world's largest cities experience water scarcity.many of people have problems with water scarcity.
The environmental impact of meat production varies because of the wide variety of agricultural practices employed around the world. All agricultural practices have been found to have a variety of effects on the environment. Some of the environmental effects that have been associated with meat production are pollution through fossil fuel usage, animal methane, effluent waste, and water and land consumption. Meat is obtained through a variety of methods, including organic farming, free range farming, intensive livestock production, subsistence agriculture, hunting, and fishing.
Peak water is a concept that underlines the growing constraints on the availability, quality, and use of freshwater resources.
This is a glossary of environmental science.
Sustainability is the ability to exist constantly. In the 21st century, it refers generally to the capacity for the biosphere and human civilization to coexist. It is also defined as the process of people maintaining change in a homeostasis balanced environment, in which the exploitation of resources, the direction of investments, the orientation of technological development and institutional change are all in harmony and enhance both current and future potential to meet human needs and aspirations. For many in the field, sustainability is defined through the following interconnected domains or pillars: environment, economic and social, which according to Fritjof Capra is based on the principles of Systems Thinking. Sub-domains of sustainable development have been considered also: cultural, technological and political. According to Our Common Future, Sustainable development is defined as development that "meets the needs of the present without compromising the ability of future generations to meet their own needs." Sustainable development may be the organizing principle of sustainability, yet others may view the two terms as paradoxical.
Water resources are natural resources of water that are potentially useful. Uses of water include agricultural, industrial, household, recreational and environmental activities. All living things require water to grow and reproduce.
Farm water, also known as agricultural water, is water committed for use in the production of food and fibre and collecting for further resources. On average, 80 percent of the fresh water withdrawn from rivers and groundwater is used to produce food and other agricultural products. Farm water may include water used in the irrigation of crops or the watering of livestock.
California's interconnected water system serves over 30 million people and irrigates over 5,680,000 acres (2,300,000 ha) of farmland. As the world's largest, most productive, and most controversial water system, it manages over 40 million acre feet (49 km3) of water per year.
The environmental impacts of irrigation relate to the changes in quantity and quality of soil and water as a result of irrigation and the effects on natural and social conditions in river basins and downstream of an irrigation scheme. The impacts stem from the altered hydrological conditions caused by the installation and operation of the irrigation scheme.
Water resource policy encompasses the policy-making processes that affect the collection, preparation, use and disposal of water to support human uses and protect environmental quality. Water policy addresses provision, use, disposal and sustainability decisions. Provision includes identification, access, preparation for use and distribution. Uses include direct human consumption, agriculture, industry and ecosystem protection. Policy must set the rules for how water is allocated to the different uses. Disposal involves wastewater treatment and stormwater/flood management. Sustainability addresses issues such as aquifer depletion, reservoir management and mineral buildup.
The global freshwater model WaterGAP calculates flows and storages of water on all continents of the globe, taking into account the human influence on the natural freshwater system by water abstractions and dams. It supports understanding the freshwater situation across the world’s river basins during the 20th and the 21st century, and is applied to assess water scarcity, droughts and floods and to quantify the impact of human actions on freshwater. Modelling results of WaterGAP have contributed to international assessment of the global environmental situation including the UN World Water Development Reports, the Millennium Ecosystem Assessment, the UN Global Environmental Outlooks as well as to reports of the Intergovernmental Panel on Climate Change. They were included in the 2012 Environmental Performance Index which ranks countries according to their environmental performance.
Arjen Hoekstra 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 associated with a range of activities, and continues to have a profound effect both on scholarship and on environmental policy and activism. He strongly supported open source science, and all his articles were published under a Creative Commons License.
A foodprint refers to the environmental pressures created by the food demands of individuals, organizations, and geopolitical entities. Like other forms of ecological footprinting, a foodprint can include multiple parameters to quantify the overall environmental impact of food, including carbon footprinting, water footprinting, and foodshed mapping. Some foodprinting efforts also attempt to capture the social and ethical costs of food production by accounting for dimensions such as farm worker justice or prices received by farmers for goods as a share of food dollars. Environmental advocacy organizations like the Earth Day Network and the Natural Resources Defense Council have publicized the foodprint concept as a way of engaging consumers on the environmental impacts of dietary choices.