The water use of Indian diets and socio-demographic factors related to dietary blue water footprint

Francesca Harris,Rosemary F Green,Edward J M Joy,Benjamin Kayatz,Andy Haines,Alan D Dangour

doi:10.1016/j.scitotenv.2017.02.085

Abstract

Agriculture accounts for ~90% of India's fresh water use, and there are concerns that future food production will be threatened by insufficient water supply of adequate quality. This study aimed to quantify the water required in the production of diets in India using the water footprint (WF) assessment method. The socio-demographic associations of dietary WFs were explored using mixed effects regression models with a particular focus on blue (irrigation) WF given the importance for Indian agriculture. Dietary data from ~7000 adults living in India were matched to India-specific WF data for food groups to quantify the blue and green (rainfall) WF of typical diets. The mean blue and green WF of diets was 737l/capita/day and 2531l/capita/day, respectively. Vegetables had the lowest WFs per unit mass of product, while roots/tubers had the lowest WFs per unit dietary energy. Poultry products had the greatest blue WFs. Wheat and rice contributed 31% and 19% of the dietary blue WF respectively. Vegetable oils were the highest contributor to dietary green WF. Regional variation in dietary choices meant large differences in dietary blue WFs, whereby northern diets had nearly 1.5 times greater blue WFs than southern diets. Urban diets had a higher blue WF than rural diets, and a higher standard of living was associated with larger dietary blue WFs. This study provides a novel perspective on the WF of diets in India using individual-level dietary data, and demonstrates important variability in WFs due to different food consumption patterns and socio-demographic characteristics. Future dietary shifts towards patterns currently consumed by individuals in higher income groups, would likely increase irrigation requirements putting substantial pressure on India's water resources.

Highlights

Growing populations and changing food consumption patterns are placing increased pressure on natural and agricultural systems
The majority of Indian Migration Study (IMS) participants resided in urban areas and the location of consumption was unlikely to give a good prediction of the location of production
This study provides individual-level estimates of the water footprint (WF) of Indian diets, finding them to have a higher blue WF than many other countries

Summary

Introduction

Growing populations and changing food consumption patterns are placing increased pressure on natural and agricultural systems. To ensure sustainable and healthy food systems, a combination of consumption- and production-side changes will be required (FAO, 2010; Smith et al, 2008). Much less evidence is available on the water use associated with the production of diets which remains a major sustainability issue as agriculture accounts for ~ 70% of global water withdrawals (FAO, 2016). The green WF represents the volume of precipitation expended during production, calculated from total rainwater evapotranspiration plus the water incorporated into the harvested crop. The blue WF represents the volume of ground and surface water delivered to crops through irrigation (Hess et al, 2015). The grey WF represents the volume of freshwater that would be required to dilute agricultural pollution to meet water quality standards (Aldaya et al, 2012). WFs are derived from feed crop WFs and drinking and service water

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