Evaluation of the influence on water consumption and water scarcity of different healthy diet scenarios

A deep understanding of the water-food nexus it is of a paramount importance as an avenue for sustainable development. Water forms the foundation for food production and a sustainable use of this resource is essential to guarantee the long-term productivity and to build resilient capacity in food and agricultural systems. Here we present methodological challenges regarding different water footprint (WF) methods applied to different dietary scenarios. The volumetric WF of three theoretical but realistic dietary patterns has been quantified (Omnivorous(O), Vegetarian(V) and Vegan(VG)), by means of the Water Footprint Network methodology. Moreover, the AWARE methodology is applied to assess potential impacts of water use trough the Water Scarcity Footprint (WSF). Diets are set to integrate and consider different drivers for food consumption encompassing the social value of the Mediterranean diet, healthy diet recommendations, food preferences of Italian consumers and the trade dimension of foodstuffs. In terms of volumetric WF, the O diet is the most water intensive one accounting for 2800 L/capita/day. A shift from an O to a V and VG diets allows to reduce the volumetric WF respectively 10% and 14%. Green water consumption accounts for the largest share (85%) in all three scenarios. Considering the WSF, V healthy diet is similar to the VG resulting in 11,069 and 11,130 L H2Oeq/capita/day respectively, whereas the O diet resulted in 11,932 L H2Oeq/capita/day. A sensitivity analysis was performed by changing each food category, one at a time, to its maximum and minimum value, in order to evaluate the significance of changes in the volumetric WF and WSF as well as the variables that mostly contribute to them. Results show that the volumetric WF associated with V and VG diets consumption overlay the O diet in respectively 53.5% and 35.7% of runs, while overlapping is improved comparing WSFs results. In this case, the WSFs of V and VG diets overlay the O diet in 83.5% of runs, suggesting that the alternative dietary scenarios would have little effect on the overall WSF and that the results are particularly sensitive to the different countries of importation. Results demonstrate the need to consider both volumetric WF and WSF with particular attention to trade analysis in order to support the development of new policies with the aim to foster sustainable consumption patterns, while preserving water resources.