Page 268 - Materials Chemistry, Second Edition

254 R.K. Rosenbaum et al.

generations) and (2) ecosystems (Bayart et al. 2010). Quantifying “the potential of a
user (humans or ecosystems) to be deprived when water is consumed in a region”
(Boulay et al. 2017) is the question normally answered at the midpoint level using
for example a scarcity indicator (or user-specific deprivation potential if they exist),
whereas assessing the potential damages from this deprivation on human health and
ecosystem quality is an endpoint assessment.
At the endpoint level, water use impact assessment is focused on the conse-
quences of the water deprivation for humans and ecosystems. The higher the
scarcity (and competition between human users), the larger the fraction of an
additional water consumption that will deprive another user. Which human user is
affected will depend on the share of each water user in a region, as well as their
ability to adapt to water deprivation. If the deprived users have access to sufficient
socio-economic resources, they may adapt and turn towards a backup technology
like desalinisation of seawater or freshwater import to meet their needs. Impacts
from human deprivation are then shifted from being solely on human health to all
impact categories that are affected by the use of this backup technology. However,
if socio-economic means are not sufficient to adapt to lower water and/or food
availability, deprivation may occur. Since the potential impacts associated with
water deprivation for humans assessed in LCA are on human health, deprivation of
water for domestic use, agriculture and aquaculture/fisheries are relevant. Domestic
users which already compete for water and have no means to compensate lower
water availability via purchasing or technological means will suffer from freshwater
deprivation, which is associated to water-related diseases caused by the use of
improper water sources and change of behaviour. Agricultural users that are
deprived of water for irrigation may produce less, which in turn will lead to lower
food availability, either locally or internationally through trade, which may increase
health damages associated with malnutrition. Similarly, lower freshwater avail-
ability for aquaculture or fisheries could lower fish supply and also contribute to
malnutrition impacts, although this was shown to be negligible in comparison to
other users’ deprivation. This impact pathway, leading to damages on human
health, is shown in Fig. 10.26.
Consuming water can also affect water availability for aquatic and terrestrial
ecosystems. If the flow of the river is altered, or the volume of the lake is reduced,
aquatic ecosystems have less habitat space and may either have to adapt or suffer a
change in species density. Since water compartments are strongly interconnected,
consuming water in a lake can affect the groundwater availability and vice versa,
and each change in availability can lead to a loss of species. Consuming water can
also alter the quality by reducing the depth of the water body for example,
increasing temperature or concentrating contaminants. Aquatic ecosystems are
dependent not only on a minimum volume for their habitat, but also on the flow
variations which are naturally influenced by seasons. Human interference with this
flow variation can also cause potential species loss. The groundwater table in some
regions directly feeds the roots of the vegetation and lowering the aquifer’s level
can mean that shorter roots species no longer reach their source of water. The
relevant mechanisms are summarised in Fig. 10.27. These impact pathways appear