Water footprint

Water footprint emerged as indicator during the late 2000s as the operationalization of virtual water concept and defined as the water needed to produce a good or service. Since then, water footprinting has developed into an important branch of biophysical assessment and covers several concerns of ecological economics. Most notably, it differentiates quantitative (blue and green) as well as qualitative (gray) appropriation and appropriation with higher (blue) or lower (green) opportunity and development costs. It also gives information of water use from the consumption and production perspective that is valuable for the design of supply and demand water management strategies and to understand the water dependency of the economic systems. The differentiation between domestic and external in line with economy-wide material flow analysis helps identify externalization. Its limitations in providing information about social drivers and environmental impacts are acknowledged. Contributions to meet these challenges already exist in a growing body of literature that favors bottom-up vs top-down methods and that is evolving towards the regionalization and temporalization. Still, its relevance in footprinting cannot be compared to that of the ecological or the carbon footprints.