Water footprints of cities – indicators for sustainable consumption and production

Abstract

Abstract. Water footprints have been proposed as sustainability indicators, relating the consumption of goods like food to the amount of water necessary for their production and the impacts of that water use in the source regions. We further developed the existing water footprint methodology, by globally resolving virtual water flows from production to consumption regions for major food crops at 5 arcmin spatial resolution. We distinguished domestic and international flows, and assessed local impacts of export production. Applying this method to three exemplary cities, Berlin, Delhi and Lagos, we find major differences in amounts, composition, and origin of green and blue virtual water imports, due to differences in diets, trade integration and crop water productivities in the source regions. While almost all of Delhi's and Lagos' virtual water imports are of domestic origin, Berlin on average imports from more than 4000 km distance, in particular soy (livestock feed), coffee and cocoa. While 42% of Delhi's virtual water imports are blue water based, the fractions for Berlin and Lagos are 2 and 0.5%, respectively, roughly equal to the water volumes abstracted in these two cities for domestic water use. Some of the external source regions of Berlin's virtual water imports appear to be critically water scarce and/or food insecure. However, for deriving recommendations on sustainable consumption and trade, further analysis of context-specific costs and benefits associated with export production will be required.

Lost water and nitrogen resources due to EU consumer food waste

“…The grey WF is an indicator of the degree of water pollution [37]. However, many authors perceive this component critically [24,38,39].…”

Diets, Food Miles, and Environmental Sustainability of Urban Food Systems: Analysis of Nine Indian Cities

“…International imports and processed food play only a minor role in the Indian food supply (FAO, 2017;Hoff et al, 2014;MSPI 2011). International imports and processed food play only a minor role in the Indian food supply (FAO, 2017;Hoff et al, 2014;MSPI 2011).…”

“…Earth's Future centers with locations of production throughout India. International imports and processed food play only a minor role in the Indian food supply (FAO, 2017;Hoff et al, 2014;MSPI 2011). To address the potential issue of allocating food's origin to a location that the shipment was only passing through, for key commodities we compared the total annual production of the commodity of a particular state, with the amount of food that was entering that state based on the freight survey data.…”

Urban water security: A review

“…Urban areas depend even more on water resources elsewhere for producing the food consumed by the urban citizens. This has been described as the 'external water footprint' of urban consumption (Hoekstra et al 2011, Hoff et al 2014. Since there are risks attached to such dependency, we speak here about the 'imported urban water risk'.…”