An advanced hydrological method for the characterization of Life Cycle Water Footprint at the local scale

ISO 14046:2014 is the standard for measuring the Water Footprint (WF) of products, processes, and organizations following a life cycle approach. The Available Water Remaining (AWARE) is an ISO 14046 compliant characterization model to measure WF characterization factors (Cf) at national and sub-national levels. Despite being established on international consensus AWARE is based on the use of global water balance models and does not incorporate knowledge on hydrological dynamics at high spatial resolution. Thus, the resulting WF values may be inaccurate for local context studies. This work proposes an approach to estimate local Cfs with a sub-administration granularity, using Tuscany Region (Italy) as a case study. Hydrological information (i.e. water availability) was retrieved from the Italian national water balance model (BIGBANG 7.0), and water consumption time-series (2012-2021) were obtained at the municipality level from regional databases. Results indicate that the yearly average Cf (~60 m3world eq / m3i) is ~80% higher than the corresponding AWARE’s Cf. High spatial and temporal variability are observed, with monthly standard deviation ranging from 0 to 52 m3world eq / m3i. The largest variability occurs in winter when the Cfs are the lowest. During summer, maximum Cf values measured show low variability due to the constant high pressure on water resources over the years. The Northwest of Tuscany, with more humid climate, presents the lowest value of Cf. In contrast, the agricultural areas result in the highest Cf due to the high-water demand for irrigation and the generally low precipitation volumes. The proposed approach can increase the reliability of WF assessments and can be extended to the entire Italian territory and other territories in the world.