Water Footprint Definition
A Water Footprint is the total volume of freshwater used to produce goods and services consumed by an individual, community or nation. It is generally expressed in terms of volume of water used per year.
A water footprint indicates the volume of water needed to sustain a nation at current levels of consumption with present technology. However, it does not indicate if the current level is above or below sustainability. It gives an indication of demand for water and increases understanding of dependence on it.
Scale of water footprints
The global water footprint is 7,450 billion cubic metres (m³) per year, which is about 1,240,000 litres annually per person, according to Chapagain and Hoekstra 2004. There are huge variations between national water footprints.
Within the UK, on average people use 3,411 litres of water per day when embedded water is taken into account. This puts the UK only slightly above the global average of 3,405 litres per day.
According to the United Nations Environment Programme 2002, twenty years ago every person on the planet had about 9,000m³ of freshwater available; 10 years later this figure dropped to 7,800m³ and by 2050 they expect it to be about 5,100m³.
There are four main factors that contribute to the water footprint of a nation:
- Consumption – amount and type often related to income
- Consumption patterns – for instance meat consumption
- Climate – affects growth conditions
- Agricultural practices – irrigation and technological efficiency
The UK has a relatively low water footprint compared to other industrialised nations; this is largely due to climatic conditions which are favourable for crop production. The USA and Canada have much larger footprints due to the amount of meat and industrial products produced and consumed within each nation. The consumption of agricultural goods contributes the most to a nation’s water footprint.
The vast majority of the UK footprint is in the form of embedded water imports, as seen in the chart below. Through the trade in commodities, a large amount of embedded water ‘flows’ around the world; about 80% of this water is from agriculture. This amount of embedded water ‘flowing’ around the world can lead to nations being dependent upon other nations for water.
The UK’s water footprint
(Source: Waterwise, data from: Chapagain and Hoekstra)
Water scarcity and dependency within the UK
The water self-sufficiency of a nation is defined as the ratio of the internal water footprint to the total water footprint of a country. It indicates the national capability to supply the water needed for the production of domestic demand for goods and services.
When the UK’s total water footprint is divided by its internal water availability the nation has a water scarcity of about 50%. This means that if the UK were to stop importing and produce all goods itself about 50% of our water resources would be consumed. This indicates that the UK could in theory survive independently, but this would not be economically or ecologically stable when labour trends and increasing population are taken into consideration.
Future scarcity
On a global scale an estimated third of the world’s population currently lives in water-stressed countries. This has been predicted to increase to two-thirds within 25 years (Source: United Nations Population Division). Africa and Asia are already hard-hit by water stress. Increasing populations will create more pressure in the coming decades.
Water saving through trade
It is possible for water self-sufficiency to approach zero if the demand for goods and services in a country are largely met with embedded water trade. Through the UK importing a large amount of embedded goods, it alleviates potential stresses and preserves internal water resources for other uses. Following this theory, nations that suffer large amounts of water stress could resolve this problem through importing water-intensive goods. For example Japan, the world’s largest grain importer, would require an additional 30 billion cubic metres of irrigation and rain water to grow the amount of food it imports.
In theory, a nation could preserve its domestic water resources by importing water-intensive products instead of producing them domestically. International trade could save water globally if a water-intensive commodity is produced in a high water resources area and traded to an area with lower water resources. However, trade has high environmental costs in the energy and fuel needed to transport the goods on a global scale.
| Related Internet links |
Waterfootprint
Information regarding water footprints of nations and products. |
Water Footprints of Nations
Chapagain, A.K. and A.Y. Hoekstra. 2004. Water Footprints of Nations, vols. 1 and 2. UNESCO-IHE Value of Water Research Report Series No. 16 |
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