Sustainable diets and biodiversity

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extraction of the raw materials up through disposal

of the waste generated by the system on the basis of

LCA methodology. Clearly, this requires the creation

of a “working model” that can fully represent the sup-

ply chain in order to take into account all aspects

which actually contribute to the formation of the GWP.

• Water Footprintor virtual water content, meas-
  ures the use of water resources in terms of volume
  (expressed in m3) of water consumed and/or pol-
  luted by the entire chain – from production to direct
  consumption of goods/services.

The indicator is closely linked to the concept of vir-

tual water (virtual water), theorized in 1993 by Pro-

fessor John Anthony Allan of King's College London

School of Oriental and African Studies, which indi-

cates the volume of freshwater consumed to pro-

duce a product (a commodity, good or service) by

summing all phases of the production chain. The

term "virtual" refers to the fact that the vast major-

ity of water used to produce the product is not phys-

ically contained in the same product, but has been

consumed during its entire life cycle.

The methodology used for the measurement of the

indicator was developed by the Water Footprint Network

(www.waterfootprint.org), a non-profit organization

of reference that operates at international level to

standardize the calculation and use of this impact

indicator. According to the protocol published in a

version updated in 2011, the Water Footprint of a

system is the sum of three specific components both

geographically and in terms of time and which cor-

responds to a different impact on the environment.

When looking at the details of agrifood chains, the

most characteristic item, but also the most complex

to evaluate, is the green water component given its

close ties to the local climatic conditions and species

cultivated as well as its productive yield. This

component is particularly important for agricultural

cultivations (it encompasses plant transpiration and

other forms of evaporation). The following formula

is used to calculate green water:

where:

•ET 0 is a factor that represents the volume of rainwater

and depends on local climatic characteristics;

•Kc depends on the plant species cultivated;

• Yield depends on the crop cultivated and climatic
  conditions of the cultivation area.

As one might easily suppose, the value of green

water of a product can vary greatly both from region

to region and from year to year, as much depends

on the value of ET0. The availability of public data-

bases and tools, made available by FAO (Food and

Agriculture Organization of the United Nations), al-

lows simple retrieval of the necessary factors for

the calculation of this contribution.

The blue water component is represented by both

the quantity of water used during industrial produc-

tion and that consumed for irrigation in the agricul-

tural phase.

Lastly, the evaluation of the grey water component

takes into account both the characteristics of water

released from the system and the natural conditions

of the receiving body in which it is released.

• Ecological Footprint, measuring the quantity of
  biologically productive land (or sea) needed to
  provide resources and absorb the emissions produced

Component Description

Green water Volume oground and cultivated vegetation. f rainwater evapotranspired from the

Blue water

Volume of freshwater, which originated from surface

or groundwater sources, used throughout the entire

chain under observation that is not repleneshed into

the basin or origin. This footprint includes both irri-

gation and process water consumption.

Grey water

Voume of polluted water associated with the produc-

tion of goods or services measured as the amount

of water (theoretically) required to dilute the pollutants

to a degree as to ensure the quality of the water.

Green water

ETO (mm)*Kc* 10

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