Page 108 - Materials Chemistry, Second Edition

Will the well run dry? Developments in water resource planning and impact assessment

Ultimately, water and eutrophication indicators assess potential rather than actual envi- 95
ronmental damage. In the case of water, the range of actual impacts is possibly wider than for
other indicators of more predictable environmental damage. For water, the assessment phase
of the LCA process becomes crucial when drawing conclusions, especially when systems are
being compared.
Alternatives to the ‘coarse’ measure of aggregate water consumption have been proposed in
order to aid impact assessment. These alternatives characterise water inputs to a system more
specifically. One such method characterises water inputs discretely into categories of use, con-
sumption and depletion, where:
s ‘use’ indicates that water resource quantities are utilised and then made available to
others
s ‘consumption’ indicates that the water resource quantities are denied to others
s ‘depletion’ indicates that water sources are either not renewed by the hydrological cycle
or cannot be sufficiently replaced at the same rates that they are used by the natural
hydrological cycle. (Owens 2002)
More detailed inventory data is required to support the characterisation proposed by
Owens, but it does appear to provide some potential solutions. It is reasonable to acknowledge
that water may be used multiple times before it is finally discharged to the environment, but
this does not necessarily mean that the aggregated water indicator should be altered.
An alternative to Owens’s approach is to retain the aggregate indicator of impact and to
expand the system being analysed to include other processes using the water discharged by the
system of interest. Water impacts would then be allocated to each system using the same body
of water input. This method is potentially more involved, yet may also generate a level of rigour
in the analysis that would ensure ‘water made available to others’ was usefully evaluated. This
system expansion method is also consistent with ISO 14040.
Figure 8.1 illustrates one way to approach expansion of the system boundary. In this
example, butter manufacture is the process of interest and, typically, the system boundary

Water
supply

Butter Products generated
manufacture e.g. butter
using water System of
interest

Mushroom Products
cultivation generated
using waste e.g. mushroom
Expanded
Expanded system
system
boundary
boundary
Figure 8.1 System boundary expansion.

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