From Field to Bottle: Water Footprint Estimation …
121
where WF green,balance is the water-balanced green WF (L
3 /unit), D r is the drainage
back to a groundwater resource under rain-fed conditions (LT
−1 ), R r is the surface
runoff under rain-fed conditions (LT
−1 ), P is the precipitation (LT
−1 ), P i is the
precipitation intercepted by the canopy that does not reach the ground (LT
−1 ).
5.2.3 Discussion
The green WF during viticulture applies to the use of rainwater during the growing
season, and should, therefore, neglect the WF impact of irrigation using freshwater
sources since this contributes to the blue WF (see Sect. 5.3). As a result, parameter
values needed for the calculation of the green WF (such as ET, drainage and runoff)
should be developed under rain-fed conditions. In Eqs. (3) and (4), this is denoted by
the subscript r. In addition, Eqs. (3) and (4) do not include a term for the rainwater
that is accumulated within the grape berry. Based on published WF assessments [27,
39], the water stored in the grape berries would only represent 0.10–0.15% of the
rainwater lost to ET. While this volume of rainwater would contribute to the green
WF, its magnitude is negligible compared to that lost to ET and, as such, can be
neglected.
5.3 Blue Water Footprint
The blue WF is a measure of freshwater abstracted from a natural freshwater source.
In contrast to the green WF, both the viticultural and vinification stages of winemaking exert a blue WF. The blue WF does not take into consideration any pollutants
or contaminants that are discharged when the freshwater is returned to the natural
environment; rather, these are considered when evaluating the grey WF (Sect. 5.4).
5.3.1 Consumptive Approach
Using the consumptive WF assessment approach, the total blue water footprint is the
sum of the volumes of freshwater abstracted from the environment that are incorporated into a product; lost to a evaporation/ET; used and discharged to a different
source from which it was taken; and/or used and returned to the same source after
being held for a prolonged period of time.
During viticulture, the blue water footprint is associated with freshwater used for
irrigation that is lost to ET, as well as any water used for diluting chemical products
and frost control.
During vinification, the blue WF represents the volume of freshwater used in
the production process that is not returned to the source from which it was taken.
Most of the freshwater use during this stage is associated with cleaning activities,
while very little is incorporated into the product or lost to evaporation. Therefore,
121
where WF green,balance is the water-balanced green WF (L
3 /unit), D r is the drainage
back to a groundwater resource under rain-fed conditions (LT
−1 ), R r is the surface
runoff under rain-fed conditions (LT
−1 ), P is the precipitation (LT
−1 ), P i is the
precipitation intercepted by the canopy that does not reach the ground (LT
−1 ).
5.2.3 Discussion
The green WF during viticulture applies to the use of rainwater during the growing
season, and should, therefore, neglect the WF impact of irrigation using freshwater
sources since this contributes to the blue WF (see Sect. 5.3). As a result, parameter
values needed for the calculation of the green WF (such as ET, drainage and runoff)
should be developed under rain-fed conditions. In Eqs. (3) and (4), this is denoted by
the subscript r. In addition, Eqs. (3) and (4) do not include a term for the rainwater
that is accumulated within the grape berry. Based on published WF assessments [27,
39], the water stored in the grape berries would only represent 0.10–0.15% of the
rainwater lost to ET. While this volume of rainwater would contribute to the green
WF, its magnitude is negligible compared to that lost to ET and, as such, can be
neglected.
5.3 Blue Water Footprint
The blue WF is a measure of freshwater abstracted from a natural freshwater source.
In contrast to the green WF, both the viticultural and vinification stages of winemaking exert a blue WF. The blue WF does not take into consideration any pollutants
or contaminants that are discharged when the freshwater is returned to the natural
environment; rather, these are considered when evaluating the grey WF (Sect. 5.4).
5.3.1 Consumptive Approach
Using the consumptive WF assessment approach, the total blue water footprint is the
sum of the volumes of freshwater abstracted from the environment that are incorporated into a product; lost to a evaporation/ET; used and discharged to a different
source from which it was taken; and/or used and returned to the same source after
being held for a prolonged period of time.
During viticulture, the blue water footprint is associated with freshwater used for
irrigation that is lost to ET, as well as any water used for diluting chemical products
and frost control.
During vinification, the blue WF represents the volume of freshwater used in
the production process that is not returned to the source from which it was taken.
Most of the freshwater use during this stage is associated with cleaning activities,
while very little is incorporated into the product or lost to evaporation. Therefore,