Baseline Water Stress
Definition:
\(BWS\) is measured as the ratio of human water demand to water availability. The impact to the environment is considered implicitly by setting conservative thresholds of water scarcity. Perhaps, it is a water stress indicator most widely used in water risk assessment platforms, including AQUEDUCT, Water Risk Filter, and many others.
Interpretation:
A higher ratio likely corresponds to higher depletion of surface and groundwater resources and more competition amongst users, as well as the associated impacts on the environment and ecosystem functions.
Calculation:
Temporal accumulation: Long-term annual average from 1980 to 2019
Spatial unit: Sub-basin
The calculation method of the \(BWS\) is updated with each version of AQUEDUCT, and here we followed the definition of the latest version, version 4.0.
where \(\overline{WW}_{m,b}\) is the long-term mean monthly human water demand in month \(m\) and \(\overline{WA}_{m,b}\) is the long-term mean monthly water availability of spatial unit \(b\) in month \(m\). The \(\overline{WA}_{m,b}\) includes renewable freshwater resources and desalinated water produced.
The \(BWS\) index provided on the Water Security Compass was calculated using the postprocessed outputs of the H08 model.
Reference:
Kuzma S. et al., 2023. “Aqueduct 4.0: Updated decision-relevant global water risk indicators.” Technical note. Washington, DC: World Resources Institute. DOI