Water-stress characterization factors for future oriented LCA | Facteurs de caractérisation de stress hydrique pour le futur pour des Analyses de Cycle de Vie

Steady-state water-stress based characterisation factors (CFs) for watersheds around the world are already available. CFs for impacts related to water use have proven to be highly spatially dependent. However, the influence of time in the obtained impact factors has not been analysed yet. To this end, this research aimed to calculate water-stress CFs for sub-watersheds in Spain for three temporal scenarios: current situation, short-term future (year 2015) and mid-term future (year 2030). Changing temporal trends in water use due to changing society and economy (ex., population, employment) and modification of regional freshwater resource availability due to already experienced and forecasted effects of climate change have been included in the calculation of the CFs. Statistical uncertainty information of the CFs for each time step is provided, taken into account that uncertainties grow with time horizon. CFs were calculated following the Water Stress Index (WSI) definition of a broadly applied water use impact characterisation method. The WSI was calculated on a yearly basis for 117 sub-watersheds covering Spain. Temporal tendency analysis of the computed CFs shows, in general, a relaxation of water stress in the short-term when compared to the current situation and afterthat a new increment. This is explained by the increase in water availability from now to the near future and then by both water use increment and water availability reduction. Large differences were detected in the comparison of the original WSI CFs at the watershed level for Spain and the WSIs calculated in this research. This may be due to the different time periods for which WSI are calculated and to the use of global maps and models used to figure out the original WSI versus regional data used here. The developed CFs are of usefulness to evaluate water use-related impacts of present and future technologies with life cycle stages located in Spain. We have shown in this study that both temporal and spatial specification matters when assessing impacts of water use.