Water is essential to the progress of human societies. Food production, electricity generation, and manufacturing, among other things, all depend on it. However, many decision-makers lack the technical expertise to fully understand hydrological information.

We present Aqueduct 4.0, the latest iteration of WRI’s water risk framework designed to translate complex hydrological data into intuitive indicators of water-related risk. We curated 13 water risk indicators—spanning quantity, quality, and reputational concerns—into a comprehensive framework. For 5 of the 13 indicators, we used a global hydrological model called PCR-GLOBWB 2 to generate novel datasets on sub-basin water supply and use.

We also used the PCR-GLOBWB 2 model to project future sub-basin water conditions using CMIP6 climate forcings. The projections centered around three periods (2030, 2050, and 2080) under three future scenarios (business-as-usual SSP 3 RCP 7.0, optimistic SSP 1 RCP 2.6, and pessimistic SSP 5 RCP 8.5).

The water risk indicators have been aggregated by category (quantity, quality, reputational, and overall) into composite risk scores using sector-specific weighting schemes. In addition, select sub-basin scores have been aggregated into country and provincial administrative boundaries using a weighted average approach, where sub-basins with more demand have a higher influence over the final administrative score.

The main audience for this technical note includes users of the Aqueduct tool, for whom the short descriptions on the tool and in the metadata document are insufficient. Key elements of Aqueduct, such as overall water risk, cannot be directly measured and therefore are not validated. Aqueduct remains primarily a prioritization tool and should be augmented by local and regional deep dives.

Key Findings:

  • The world is facing an unprecedented water crisis. New data from WRI’s Aqueduct Water Risk Atlas finds that 25 countries – one-quarter of the world’s population - are currently exposed to extremely high water stress annually. Globally, around 4 billion people, half the world’s population are exposed to water stress for at least one month a year. By 2050, that number could be closer to 60%.
  • According to new data from Aqueduct, $70 trillion in GDP (31% of global GDP) will be exposed to high water stress by 2050, up from $15 trillion (24% of global GDP) in 2010. Just 4 countries — India, Mexico, Egypt and Turkey — account for over half of the exposed GDP in 2050.
  • Water is central to meeting the world’s climate goals, feeding a growing population and meeting people’s basic needs for survival. But the world is failing to prioritize water issues. As countries push for a just transition away from fossil fuels, they must also transform how they manage water.
  • The world needs to urgently address the water crisis. Cost-effective solutions exist; now we need the political will and financial backing. Every level of government, communities and businesses must step up to build a water-secure future for all.
Graphic showing global water stress.