Spatial and temporal specific characterisation factors for water use impact assessment in Spain

Regionalised characterisation factors (CFs) for watersheds around the world are available to assess water use-related environmental impacts. The main problem with using the watershed regionalisation level arises when a single CF is generated for large watersheds in countries where water availability and demand are not uniform. Additionally, water availability and use vary over time because of the effects of climate change and changing human lifestyles. These two factors are currently not taken into account in CFs, but should be included for the sake of the accuracy of LCA results. The aim of this research was to provide water stress index CFs at the sub-watershed spatial level for three temporal scenarios (present, short-term future and mid-term future) for Spain (Southern Europe), a country with considerable variability in water availability that is especially vulnerable to climate change effects.

CFs were calculated following the water stress index (WSI) definition of Pfister et al. (Environ Sci Technol 43(11):4098–4104, 2009). The WSI was calculated on a yearly basis for 117 sub-watersheds—compared to 56 regionalisation units provided in the original method—and for (i) the current situation: current water use and availability; (ii) short-term future: projections for 2015; and (iii) mid-term future: projections for 2030. The uncertainties of the CFs were calculated for each sub-watershed.

Temporal trend analysis of the CFs showed a general relaxation of water stress over the short-term when compared to the current situation, followed by a new increase. Major differences were noticed in the WSIs calculated by Pfister et al. (Environ Sci Technol 43(11):4098–4104, 2009) using global data and maps and the WSIs calculated in this study using national and regional data. The WSIs under consideration of uncertainty were higher than the deterministic result for intermediate WSIs.

The CFs generated are useful compared with the CFs previously available because they improve evaluation of the water use-related impacts of present and future technologies with the life cycle stages located in Spain. We encourage LCA developers to update WSIs for other countries using information at the national level that is usually freely accessible.