Elsevier

Ecological Indicators

Volume 74, March 2017, Pages 420-426
Ecological Indicators

Volumetric water footprints, applied in a global context, do not provide insight regarding water scarcity or water quality degradation

https://doi.org/10.1016/j.ecolind.2016.12.008Get rights and content

Abstract

Many authors have presented estimates of volumetric water footprints in the context of describing and comparing the water requirements of crop production and industrial activities. In recent years, water footprints have been proposed as indicators for use in assessing the sustainability, efficiency, and equity of water allocations in a global context. That perspective is notably ambitious, given that volumetric water footprints contain information pertaining to just one resource, with no consideration of scarcity values, opportunity costs, or the impacts of water use on the environment, livelihoods, or human health. The suggestion that water scarcity must be assessed from a global perspective also is misplaced. Water scarcity and water quality degradation arise in local and regional settings. The impacts and potential remedies must be evaluated at those levels, by scientists and public officials charged with determining the policies and investments needed to ensure wise use of water resources. Efforts to extend access to clean, safe, and affordable water to the millions of households lacking such access also must be designed and implemented locally. Public officials will not gain useful insight by comparing volumetric water footprints in a global context. Water scarcity and water quality degradation cannot be resolved by reorganizing production activities across river basins and continents.

Introduction

In a recent contribution to Ecological Indicators, Hoekstra (2016) critiques the scarcity-weighted water footprint that has been proposed for use in life cycle assessments, and has been adopted by the International Organization for Standardization (ISO) as the preferred method for calculating and reporting water footprints (ISO, 2014; Pfister et al., 2015). Much of the author’s critique reflects his perspective that water scarcity is a global issue, and that water allocation across competing uses should be viewed in a global context (Hoekstra and Mekonnen, 2012, Hoekstra and Wiedmann, 2014). In particular, Hoekstra (2016) suggests that because the global demand for water is increasing, policy makers must measure and compare the pressure that all products place on the global water supply. To this end, Hoekstra (2016) proposes that the volumetric water footprint promoted by the Water Footprint Network is superior to the scarcity-weighted water footprint adopted by the ISO. He suggests also that accounting for water scarcity within river basins or in a local or regional context is not appropriate, because water use in any basin reduces the volume of water remaining for other uses at some location within the global context.

Much of the discussion in Hoekstra (2016) mischaracterizes water scarcity and its impacts on the environment, natural resources, livelihoods, and human health. My goal in this paper is to demonstrate the inaccuracies in that discussion and to describe alternative perspectives regarding water scarcity, allocation, and use in both rainfed and irrigated settings. It is not my goal to take sides in the discussion regarding which water footprint should have been adopted for use in the ISO framework. I do not assess the method for calculating the scarcity-adjusted water footprint proposed by other authors (Ridoutt and Pfister, 2010, Ridoutt and Pfister, 2013, Boulay et al., 2015a, Boulay et al., 2015b). Rather, I seek to set aside the notion that a volumetric water footprint, which does not account for water scarcity, can provide meaningful guidance regarding water policies, investments, or water allocations. Volumetric water footprints are silent on the issues that matter most in determining whether water allocations are sustainable, efficient, or equitable (Wichelns, 2015a). It is not possible to assess those issues and to determine optimal policies and investments only by calculating the volume of water consumed in a given process or chain of processes.

I endeavor also to demonstrate the importance of considering water scarcity in local and regional settings. Although water is a global resource, as described quite well by the hydrologic cycle, water scarcity is a local and regional issue. It is essential that local and regional water users and policy makers assess scarcity conditions in their domains, and implement appropriate policies, incentives, and strategies to manage water wisely. Investments in extending access to water and improving water quality also must be evaluated and implemented locally. The global perspective described by Hoekstra (2016) is incorrect. One cannot successfully address matters of water scarcity or water quality degradation without considering local or regional issues and solutions.

In sum, I describe four perspectives that contrast with those presented in Hoekstra (2016): 1) Water scarcity is not a global issue, 2) The impacts of water use vary with location and with time, 3) Irrigated agriculture cannot be replaced by improving the productivity of rainfed agriculture, and 4) Local water scarcity and water quality degradation impair the health of millions of urban and rural residents, worldwide.

Section snippets

Water scarcity is local and regional

Hoekstra (2016) suggests that because water is a global resource, water depletion also has a global character. In the author’s view, water use in any location subtracts from the sum of global water available for other uses. Thus, the environmental impact of water use in any location is the same: “Every litre of water consumption, whether in a water-rich or water-poor river basin, and whether [soil moisture, effective rainfall, surface water, or groundwater], will reduce the water volume

Water use impacts vary across locations and seasons

Hoekstra (2016) suggests that the environmental impact of water use is the same in water abundant and water scarce basins. In his view, “global water availability is the sum of the water [available] in the various basins in the world; some of them contribute a lot to overall availability, others only a little.” Hence, water withdrawals and use in any basin impact global water availability in equivalent fashion. Furthermore, the author suggests that “producing more water-intensive products where

Rainfed agriculture will not replace irrigated production

Hoekstra (2016) suggests also that improvements in the productivity of rainfed agriculture would reduce the need for irrigation, thus reducing also the scarcity of surface water and groundwater. To this end, “An essential component in solving the over-consumption of [surface water] and [groundwater] and associated environmental impacts in water-scarce areas is to use [soil moisture and effective rainfall] more productively in water-abundant areas, because if water-intensive products are

Local water scarcity impairs the health of millions

Hoekstra (2016) suggests that the attempts of some authors to assess the impacts of water scarcity on the environment and human health, using a water stress index or scarcity-adjusted measures of water footprints (Pfister et al., 2009, Ridoutt and Pfister, 2013, Hess et al., 2015) are not appropriate, as the proposed metrics have no empirical interpretation. As noted above, it is not my goal to critique the scarcity-adjusted water footprint indicators. However, the discussion put forth by

Summing up

Much of the discussion in the critique of the water-scarcity weighted water footprint, presented in Hoekstra (2016), mischaracterizes water scarcity and its impacts on the environment, natural resources, livelihoods, and human health. Water scarcity is not a global issue, but rather a local and regional issue that requires analysis, policies, and investments at those levels. Volumetric water footprints do not contain the information needed to assess water scarcity because they do not consider

Acknowledgment

I appreciate the comments of two reviewers who have helped me to clarify and enhance the discussion.

References (78)

  • H. Hengsdijk et al.

    Modeling the effect of three soil and water conservation practices in Tigray Ethiopia

    Agric. Ecosyst. Environ.

    (2005)
  • T.M. Hess et al.

    Comparing local and global water scarcity information in determining the water scarcity footprint of potato cultivation in Great Britain

    J. Clean. Prod.

    (2015)
  • A.Y. Hoekstra

    Human appropriation of natural capital: a comparison of ecological footprint and water footprint analysis

    Ecol. Econ.

    (2009)
  • A.Y. Hoekstra

    A critique on the water-scarcity weighted water footprint in LCA

    Ecol. Indic.

    (2016)
  • Z. Huang et al.

    Heavy metals in vegetables and the health risk to population in Zhejiang, China

    Food Control

    (2014)
  • N.I. Khan et al.

    Household’s willingness to pay for arsenic safe drinking water in Bangladesh

    J. Environ. Manage.

    (2014)
  • A. Overbo et al.

    On-plot drinking water supplies and health: a systematic review

    Int. J. Hyg. Environ. Health

    (2016)
  • T. Oweis et al.

    Optimizing supplemental irrigation: tradeoffs between profitability and sustainability

    Agric. Water Manage.

    (2009)
  • C. Perry

    Water footprints: path to enlightenment, or false trail?

    Agric. Water Manage.

    (2014)
  • M. Qadir et al.

    The challenges of wastewater irrigation in developing countries

    Agric. Water Manage.

    (2010)
  • S. Raja et al.

    Socio-economic background of wastewater irrigation and bioaccumulation of heavy metals in crops and vegetables

    Agric. Water Manage.

    (2015)
  • B.G. Ridoutt et al.

    A revised approach to water footprinting to make transparent the impacts of consumption and production on global freshwater scarcity

    Global Environ. Change

    (2010)
  • J. Rockström et al.

    Rainwater management for increased productivity among small-holder farmers in drought prone environments

    Phys. Chem. Earth.

    (2002)
  • K. Vohland et al.

    A review of in situ rainwater harvesting (RWH) practices modifying landscape functions in African drylands Agriculture

    Ecosyst. Environ.

    (2009)
  • M.B. Wakeyo et al.

    Does water harvesting induce fertilizer use among smallholders?: Evidence from Ethiopia

    Agric. Syst.

    (2013)
  • D. Wichelns

    Virtual water and water footprints do not provide helpful insight regarding international trade or water scarcity

    Ecol. Indic.

    (2015)
  • M.A. Abedin et al.

    Community perception and adaptation to safe drinking water scarcity: salinity, arsenic, and drought risks in coastal Bangladesh

    Int. J. Disaster Risk Sci.

    (2014)
  • A. Al-Assaf et al.

    A trade-off analysis for the use of different water sources for irrigation (the case of Southern Shounah in the Jordan Valley)

    Water Int.

    (2007)
  • N. Alexandratos et al.

    World Agriculture Towards 2030/2050: The 2012 Revision, ESA Working Paper 12-03

    (2012)
  • S. Amrose et al.

    Safe drinking water for low-income regions

    Annu. Rev. Environ. Resour.

    (2015)
  • J. Bartram et al.

    Global monitoring of water supply and sanitation: history, methods and future challenges

    Int. J. Environ. Res. Public Health

    (2014)
  • A. Bogale

    Vulnerability of smallholder rural households to food insecurity in eastern Ethiopia

    Food Secur.

    (2012)
  • A.-M. Boulay et al.

    Analysis of water use impact assessment methods (part B): applicability for water footprinting and decision making with a laundry case study

    Int. J. Life Cycle Assess.

    (2015)
  • A.-M. Boulay et al.

    Analysis of water use impact assessment methods (part A): evaluation of modeling choices based on a quantitative comparison of scarcity and human health indicators

    Int. J. Life Cycle Assess.

    (2015)
  • J.F. Chamberlain et al.

    Water-supply options in arsenic-affected regions in Cambodia: targeting the bottom income quintiles

    Sci. Total Environ.

    (2014)
  • R.D. Chithranayana et al.

    Identification of drought prone agro-ecological regions in Sri Lanka

    J. Natl. Sci. Found. Sri Lanka

    (2008)
  • R.D. Chithranayana et al.

    Adaptation to the vulnerability of paddy cultivation to climate change based on seasonal rainfall characteristics

    J. Natl. Sci. Found. Sri Lanka

    (2014)
  • S.E. Cook et al.

    Water, food and livelihoods in river basins

    Water Int.

    (2009)
  • F. Ellis et al.

    Rural livelihoods and poverty reduction strategies in four African countries

    J. Dev. Stud.

    (2004)
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