A vast amount of water is used to produce the food and products that nations consume. Large population is the greatest factor, but inefficient agriculture or dependence on water-intensive cuisine can exacerbate demand; meat consumption accounts for 30 percent of the U.S. water footprint.
Certain countries, such as India and the U.S., also export significant quantities of water in the form of food and products, despite their own robust consumption. Populous nations that have little land or little water are huge net importers.
Those insights come from engineers Arjen Y. Hoekstra and Mesfin M. Mekonnen of the University of Twente in the Netherlands. Over the long term, net exporters may want to alter trade policies to avoid creating their own water shortages or raise prices to reflect the cost of increasingly scarce water resources. Inefficient water nations might improve agricultural practices. And net importers might lower exports to save water for domestic use.
This article was published in print as "Water In, Water Out."
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17 Comments
Add CommentHow would this change if it were done "per capita?"
Reply | Report Abuse | Link to thisCalculated the per person per day numbers for countries that interested me:
Reply | Report Abuse | Link to thisChina: 2781 lts/day
India: 2591 lts/day
US: 7175 lts/day
Japan: 3752 lts/day
Quickly grabbing populations from Wikipedia (http://en.wikipedia.org/wiki/List_of_countries_by_population) and dividing yields:
Reply | Report Abuse | Link to this1 US 2619 m^3/yr/person
2 Russia 1890
3 Brazil 1847
4 Mexico 1757
5 Japan 1370
6 Pakistan 1110
7 China 1015
8 Indonesia 977
9 Nigeria 968
10 India 946
To get a sense of the per capita numbers, check out the source paper: http://www.pnas.org/content/early/2012/02/06/1109936109 Niger uses the most freshwater per capita (3,519 m3/yr/cap), with a huge percentage sunk into agriculture (specifically cereals). Followed by Bolivia, U.S., Portugal, and Spain.
Reply | Report Abuse | Link to thisGolf. Golf uses more water than God.
Reply | Report Abuse | Link to this"Rewards"? In what Universe is having a large proportion of your population verging on constant dehydration a reward whilst having to export vast amounts of water simply to keep your economy afloat a reward?
Reply | Report Abuse | Link to thisHe means rewards, as in massively decreases the statistic only.
Reply | Report Abuse | Link to thisThis is a useful webpage if you want to find out per capita consumption of different countries:
Reply | Report Abuse | Link to thishttp://www.waterfootprint.org/?page=cal/waterfootprintcalculator_national
"Certain countries, such as India and the U.S., also export significant quantities of water in the form of food and products" ....Based on rough pecking around for numbers on various government sites... a rough estimate should be around 17-20% of US total water usage being attributed to agricultural exports. ~$250B industry with ~$50B trade surplus... Can't find info easily on Inida... or China...
Reply | Report Abuse | Link to thispokerplayer: "Per capita analysis rewards nations with unsupportable population growth.'
Reply | Report Abuse | Link to thisSo true. The logic is the same with carbon emissions. Canada can reduce it's per capita carbon imprint by women doubling births to an average 2.6 instead of the current 1.3
In contrast Kenyan womaen have 7.1 kids...so good for the environmnet!
The water usage is not completely based on population. You have to consider distribution along the agriculture, industrial and other sectors.
Reply | Report Abuse | Link to thisThis is not the question - it is a red herring - the question is how much water is created each year by desalinization of the oceans - in the form of rain - IMO we use between 1% and 5% of available water.
Reply | Report Abuse | Link to thisSo, we do not have a shortage problems we have a management problem - build more dams and lakes in major river system it will stop flooding and permit discharge to maintain delta areas.
Man - a creature made at the end of the week's work when God was tired.
Mark Twain
Without knowing why you want a particular measure quantified it is hard to give much weight to any of these numbers. But they are interesting, at least until they are used to justify some political agenda. For example, I would worry more if I saw these figures normalized to present as net loss of water reserves, or time to depletion. If, for example, the US is exporting 1% of its reserve each year, then I'd want to start watching the reserves as global climate changes shifts the replenishment rates. And at some point I might want to reduce the loss rate. I like to remind people that two of the biggest agricultural exports from Minnesota are probably dirt (down the Mississippi) and water (in food).
Reply | Report Abuse | Link to thisI thought a dam caused flooding ... at least the reservoir area would be permanently flooded ... no?
Reply | Report Abuse | Link to thisWhere is the explanation of how figures are calculated? For instance, is any allowance made for the fact that most of the water used in grass fed beef production is continually recycled as part of the natural water cycle.(See kellner on bovine metabolism).
Reply | Report Abuse | Link to thisBotanists broadly accept that transpiration rates of full cover crops approximate evaporation rates from open water.
Conventional carbon sequestration inevitably involves transpiration.
I've often wondered if it really made sense to exhort individuals to turn off lights and take shorter showers because the bulk of the usage of energy and water isn't done by individuals at home. This graphic seems to confirm that fact.
Reply | Report Abuse | Link to thisAccording to the World Bank, Kenya's fertility rate is only 4.72 children per woman. Just google "fertility rate of Kenya". However, I agree with you that such a rate is still too high and that people need to reduce the birth rate all over the world.
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