CONCEPTS ON WATER FOOTPRINT AND VIRTUAL WATER

Pradip K Sengupta
Water footprint is a new concept in the field of water management. It is expected that if water consumption or need of a country is assessed on the basis of water footprint an efficient water management practice can be achieved. To allocate water in individual sectors and for finding political solutions of a water conflict water footprint and virtual water can contribute a lot. The concept of water footprint is introduced recently at the beginning of this century. The concept was originally launched by A.Y. Hoekstra in the year 2002. A document on water footprint has been released by the UNESCO-IHE in 2002. In that document an attempt was made to assess the water footprint of individual nations. But what is a water foot print? Water footprint is a consumption based indicator of water use. The water footprint of an individual, business or nation is defined as the total volume of freshwater that is used to produce the foods and services consumed by the individual, business or nation. A water footprint is generally expressed in terms of the volume of water use per year. The calculation of water footprint is based on the amount of agriculture product, meat, industrial product and raw water consumed by an individual, business or nation.
Each product, whether agricultural or industrial consume some amount of water in the production process. In agriculture water is consumed from soil, and lost through evapo-transpiration. Similarly when meat is produced water requirement is increased because water is consumed by the animal through fodder and direct utilization of water.
The water footprint of a country (NWFP) has two parts. One is the internal water footprint (IWFP) and another is the external water footprint (EWFP).
The internal water footprint of a nation is the volume of water used from domestic water resources to produce the goods and services consumed by the inhabitants of the country. The external water footprint of a country is the volume of water used in other countries to produce goods and services imported and consumed by the inhabitants of the country.

So NWFP=IWFP+EWFP
In order to promote sustainable, fair and efficient use of water on a global scale seven global groups have launched the Water Footprint Network in October, 2008. Their aim is to work toward a common approach to water footprint measurement, accounting, and reporting. Partners of this group are the World Business Council for Sustainable Development, the University of Twente in the Netherlands, WWF, UNESCO-IHE Institute for Water Education, the Water Neutral Foundation, the International Finance Corporation (part of the World Bank Group); and the Netherlands Water Partnership.

India has the largest water footprint in the world (987 Gm3/yr) but it also has a very high national self-sufficiency ratio (98%), The total which implies that at present India is only little dependent on the import of virtual water from other countries to meet its national demands. Whereas Bangladesh has its renewable water resource to the tune of


VIRTUAL WATER
The water required for production of a commodity, good or service is called virtual water. This means that the amount of water required for producing a unit amount of that product is the virtual water of that product. So when we consume anything we are actually consuming the virtual water for that product. The concept of virtual water was introduced by Professor John Allan of King’s College, London, in 1997 as an economic tool and an alternative means of measuring the global distribution of water through trade and was awarded the 2008 Stockholm Water Prize for it. In the past the in place of virtual water the term embedded water was in use. But virtual water has gained interest of the scientists and the term is now accepted as a term used for measuring the environmental cost in terms of water. In the same way trade of a commodity or service may be translated as the trade of virtual water.
The virtual water of an agricultural product in a country may be different from that of the same product produced in a different country. For example tomato produced in USA contains less virtual water than tomato produced in Israel. This happens due to the difference in climatic condition between those countries. It is becoming evident that some water scarce countries will likely import food that is water intensive to produce.
To determine the virtual water use we need data on crop water requirements over the growing season, evapotranspiration rates, the annual yield and the amount of water used in processing the crop.( Hans Schreier, Les Lavkulich and Sandra Brown May 2007) .The concept of Virtual Water should be an additional consideration in all water balance calculations.
The virtual water content of different food products in India. (afterVijay Kumar* and Sharad K. Jain2007)
Product Virtual water (cubic m/tonne)
Agricultural Product
Wheat 1654
Rice (paddy) 2850
Mustard oil 4643
Maize 1937
Banana 415
Orange 364
Sugarcane 159
Grapefruit 411
Lentils 6652
Apple 1812
Soybeans 4124
Pear 1287
Jute 2823
Cotton lint 18694
Potatoes 213
Tomato 302
Coffee (roasted) 14500
Tea (green) 1804
Sugar (refined) 1391
Groundnut oil 8875
Product Virtual water (cubic m/tonne)
Livestock and livestock products
Bovine meat 7386
Milk powder 6368
Swine 4119
Yogurt/milk product 1592
Sheep 3397
Buttermilk 2068
Goat 3018
Cheese 6793
Fowl/poultry 6024
Egg (birds) 7531
Leather (bovine) 17710

Virtual water trade is another concept that can be related to trade of commodities.
The virtual water consumption of a country can therefore be = domestic virtual water+ imported virtual water- exported virtual water.
If the virtual water import is higher than the export then the country is a water importer. Virtual water may become an additional consideration in deciding what to export/import. This concept can be useful in making agricultural choices within the country among various states. But this new concept has not yet been used in decision making processes in most areas. It may also be added that for evolving water management policies, the concept of virtual water has to be used along with other aspects such as hydrology, geology, agriculture, engineering, land use, culture etc. It is not advisable that all decisions on water allocation should be based solely on virtual water assessment. At the global level, virtual water trade has geo-political implications: it induces dependencies between countries. Therefore, it can be regarded either as a stimulant for co-operation and peace or a reason for potential conflict.
SOURCES

http://news.moe.org.ir/vdce.z8xbjh8f7k1ij.html%2020_6_09
Chapagain, A. K. and Hoekstra, A. Y. (2003). Virtual water flows between nations in relation to trade in livestock and livestock products. Value of Water Research Report Series No. 13, UNESCO-IHE Institute for Water Education, Delft, The Netherlands.
Real and Virtual Water and Water Footprints:A Comparison between the Lower Fraser Valley and the Okanagan Basin Hans Schreier, Les Lavkulich and Sandra Brown, Final Report for the Walter and Duncan Gordon Foundation May 2007
Virtual water trade … iran http://news.moe.org.ir/vdce.z8xbjh8f7k1ij.html%2017th%20may%202009
Vijay Kumar* and Sharad K. Jain, CURRENT SCIENCE, VOL. 93, NO. 8, 25 OCTOBER 2007