Global water scarcity including surface water quality and expansions of clean water technologies

Michelle T H Van Vliet,John R Yearsley,Yoshihide Wada,Martina Flörke,Naota Hanasaki,Edward R Jones,Wietse H P Franssen

doi:10.1088/1748-9326/abbfc3

Abstract

Water scarcity threatens people in various regions, and has predominantly been studied from a water quantity perspective only. Here we show that global water scarcity is driven by both water quantity and water quality issues, and quantify expansions in clean water technologies (i.e. desalination and treated wastewater reuse) to ‘reduce the number of people suffering from water scarcity’ as urgently required by UN’s Sustainable Development Goal 6. Including water quality (i.e. water temperature, salinity, organic pollution and nutrients) contributes to an increase in percentage of world’s population currently suffering from severe water scarcity from an annual average of 30% (22%–35% monthly range; water quantity only) to 40% (31%–46%; both water quantity and quality). Water quality impacts are in particular high in severe water scarcity regions, such as in eastern China and India. In these regions, excessive sectoral water withdrawals do not only contribute to water scarcity from a water quantity perspective, but polluted return flows degrade water quality, exacerbating water scarcity. We show that expanding desalination (from 2.9 to 13.6 billion m3 month−1) and treated wastewater uses (from 1.6 to 4.0 billion m3 month−1) can strongly reduce water scarcity levels and the number of people affected, especially in Asia, although the side effects (e.g. brine, energy demand, economic costs) must be considered. The presented results have potential for follow-up integrated analyses accounting for technical and economic constraints of expanding desalination and treated wastewater reuse across the world.

Highlights

IntroductionA growing worldwide population strongly increases the demands for clean water for different sectoral water uses (e.g. irrigation, domestic, energy, manufacturing uses) (Biswas and Tortajada 2018)
A growing worldwide population strongly increases the demands for clean water for different sectoral water uses (Biswas and Tortajada 2018)
We show that global water scarcity is driven by both water quantity and water quality issues, and quantify expansions in clean water technologies to ‘reduce the number of people suffering from water scarcity’ as urgently required by UN’s Sustainable Development Goal 6

Summary

Introduction

A growing worldwide population strongly increases the demands for clean water for different sectoral water uses (e.g. irrigation, domestic, energy, manufacturing uses) (Biswas and Tortajada 2018). Climate change induced increases in the frequency and intensity of hydro-climatic extremes (e.g. droughts, floods) (Dankers et al 2014, Prudhomme et al 2014, Trenberth et al 2014), combined with increasing intensification of agriculture, industrialisation, urbanisation, and water extractions and uses, aggravate water quality deterioration, in developing countries (Macdonald et al 2016, UNEP 2016, Sinha et al 2017). These changes will challenge sustainable management of ‘clean accessible water for all’, one of the UN Sustainable Development Goals (SDGs) for 2030 (UN 2015). Previous work by Vanham et al (2018) evaluated the shortcomings of this water scarcity indicator, including the absence of water quality, the lack of consideration of unconventional water resources, and the weak temporal (annual) and spatial (country) resolutions used in most water scarcity assessments (Vanham et al 2018)

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Conclusion