Estimating the global production and consumption-based water footprint of a regional economy

The current scenario of increasing use and pollution of water resources and the effects of climate change on natural supply coexist with a high trade interconnection, where impacts are transmitted from local to global scales. Identifying and quantifying these impacts is essential to focus and coordinate policies for sustainability. In this context, this study develops a methodology to estimate the pressures of a regional economy on global water resources. Unlike previous studies, which have focused mainly on the regional and national blue water footprint (WF) of consumption, the proposed framework integrates in an innovative way: i) an estimation of the global green, blue and grey WF, ii) a comparison between production and consumption-based approaches, iii) a spatial disaggregation, and iv) a scarcity-based assessment. Specifically, a regional input-output (IO) model and a global multiregional IO model are used, which allows identifying the origin and quantifying the water incorporated in imports. The Tuscany region in Italy is considered as a case study, where the domestic WF has been studied, but global impacts on water resources are unknown. The results show that, although 42.7 % of Tuscany's imports come from outside Italy, the pressures on water resources exerted abroad represent 81.2 % (production) and 73.4 % (consumption) of total. This result is amplified when only water incorporated under scarcity conditions is considered, reaching 96.3 % (production) and 94.6 % (consumption). The proposed approach allows characterizing the most significant impacts, which could guide policies to promote the consumption and import of products with low water incorporated under stress conditions.