Daugherty Water for Food Global Institute


Date of this Version


Document Type



Science of the Total Environment 613–614 (2018) 218–232.

doi 10.1016/j.scitotenv.2017.09.056


© 2017 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license


Target 6.4 of the recently adopted Sustainable Development Goals (SDGs) dealswith the reduction ofwater scarcity. To monitor progress towards this target, two indicators are used: Indicator 6.4.1 measuring water use efficiency and 6.4.2 measuring the level of water stress (WS). This paper aims to identify whether the currently proposed indicator 6.4.2 considers the different elements that need to be accounted for in a WS indicator.WS indicators compare water use with water availability.We identify seven essential elements: 1) both gross and net water abstraction (or withdrawal) provide important information to understand WS; 2) WS indicators need to incorporate environmental flow requirements (EFR); 3) temporal and 4) spatial disaggregation is required in a WS assessment; 5) both renewable surface water and groundwater resources, including their interaction, need to be accounted for as renewablewater availability; 6) alternative availablewater resources need to be accounted for as well, like fossil groundwater and desalinated water; 7)WS indicators need to account for water storage in reservoirs, water recycling and managed aquifer recharge. Indicator 6.4.2 considers many of these elements, but there is need for improvement. It is recommended thatWS is measured based on net abstraction as well, in addition to currently onlymeasuring WS based on gross abstraction. It does incorporate EFR. Temporal and spatial disaggregation is indeed defined as a goal in more advanced monitoring levels, inwhich it is also called for a differentiation between surface and groundwater resources. However, regarding element 6 and 7 there are some shortcomings for which we provide recommendations. In addition, indicator 6.4.2 is only one indicator, which monitors blueWS, but does not give information on green or green-bluewater scarcity or on water quality.Within the SDG indicator framework, some of these topics are covered with other indicators.