EGU24-13855, updated on 09 Mar 2024
EGU General Assembly 2024
© Author(s) 2024. This work is distributed under
the Creative Commons Attribution 4.0 License.

Integrated water scarcity index reveals increased exposures of populations and areas to water scarcity

Zhonghao Fu1,2,3, Wenfeng Liu1,2,3, Yawei Bai1,2,3, Michelle T. H. van Vliet4, Philippe Ciais5, Kyle Frankel Davis6,7, and Yoshihide Wada8,9
Zhonghao Fu et al.
  • 1State Key Laboratory of Efficient Utilization of Agricultural Water Resources, Beijing 100083, China.
  • 2National Field Scientific Observation and Research Station on Efficient Water Use of Oasis Agriculture in Wuwei of Gansu Province, Wuwei 733000, China.
  • 3Center for Agricultural Water Research in China, College of Water Resources and Civil Engineering, China Agricultural University, Beijing 100083, China.
  • 4Department of Physical Geography, Utrecht University, P.O. Box 80.115, 3508 TC, Utrecht, the Netherlands.
  • 5Laboratoire des Sciences du Climat et de l’Environnement, LSCE/IPSL, CEA-CNRS-UVSQ, Université Paris-Saclay, Gif-sur-Yvette, France.
  • 6Department of Geography and Spatial Sciences, University of Delaware, Newark, Delaware, USA.
  • 7Department of Plant and Soil Sciences, University of Delaware, Newark, Delaware, USA.
  • 8International Institute for Applied Systems Analysis, Laxenburg, Austria.
  • 9Climate and Livability, Biological and Environmental Science and Engineering Division, King Abdullah University of Science and Technology, Thuwal, Saudi Arabia

Freshwater resources are fundamental to supporting humanity, and measures of water scarcity have been critical for identifying where human water requirements and water availability are imbalanced. Traditional metrics for water scarcity primarily focus on actual blue water withdrawal, while the contribution of rain-fed water requirements (RWR) and water quality – dimensions with important implications for multiple societal sectors – to overall water scarcity remains unclear. Here we address this gap by explicitly merging the three dimensions of water scarcity into an integrated index (iWSI). Specifically, combining a process-based crop water model with spatially detailed information on water pollution and sector-specific withdrawals, we first develop global gridded (30 arcminute) estimates of iWSI and its individual dimensions (blue water, RWR, and water quality) averaged over the period 2001–2010. We then perform a quantitative comparison of water scarcity indices that consider different combinations of the three water scarcity dimensions, together or in isolation, and estimate their water withdrawals and associated global land area and population under conditions of monthly and annual water scarcity. We find that the global land area and population under water scarcity increases by 126% (119–133%) and 53% (49–57%) using this integrated index relative to assessments focusing only on blue water. These effects are most pronounced for populations in Africa and Asia. Examining seasonal water scarcity, we estimate that 4.4 billion people are exposed to integrated water scarcity at least one month per year – 31% more people than under blue water scarcity alone. Our research highlights that water scarcity challenges are more widespread than previously understood. As such, our findings underscore the need for actions to bring human pressure on freshwater resources into balance with both water quantity and quality, addressing previously overlooked blindspots in global water sustainability.

How to cite: Fu, Z., Liu, W., Bai, Y., van Vliet, M. T. H., Ciais, P., Davis, K. F., and Wada, Y.: Integrated water scarcity index reveals increased exposures of populations and areas to water scarcity, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13855,, 2024.