Water is a scarce commodity. It is not just needed for drinking purposes, but most importantly for agriculture. If you lose water or don’t have freshwater resources, you cannot have any crops. There is a trade going on – often unbeknownst to many countries which are the victims of these surreptitious flows – where some water surplus countries do not use their own water but use the land and water under it from another, often poor and even water-scarce countries and societies, to outsource their agricultural produce and import it. With that produce comes the water. Virtual water trade. We have discussed this concept briefly in our post on how Saudi Arabia handles its water crisis.
Water Footprint and Virtual Water Trade
What is it? Virtual Water Trade refers to the volumes of water that are embedded (or used) in the flow of exports and imports of products to and from a country or region. For example, 1 kg of wheat requires 1350 liters of water. That is the Water footprint of wheat. The Water footprint of different food commodities underlies the virtual water trade that is going on when those food products are imported or exported.
Virtual water is embedded in agricultural, forestry, industrial, and mining products
The water footprint can be further divided into
Green water footprint is the fraction of the WF that is contributed by green water (i.e. precipitation water directly contributing to the soil water balance in the crops’ root zone in the absence of irrigation). Blue water footprint is the fraction of the WF that is contributed by the consumptive use of blue water (i.e. irrigation water withdrawn from surface water bodies and aquifers). Grey water footprint is an indicator of freshwater pollution defined as the water volume required to dilute pollutants to a concentration that meets the water quality standards.