Baseline Water Stress (BWS) 4.0

Definition:

Baseline Water Stress (BWS) 4.0 is a water scarcity indicator defined as the ratio of total human water requirement to available water resources. Environmental impacts are implicitly incorporated by establishing thresholds that signify water scarcity levels. As the BWS calculation methodology has been updated with each WRI Aqueduct release, the WSC adopts the methodology defined in the latest version (4.0). To ensure clarity and precision, this metric is designated BWS 4.0 within the WSC.

Interpretation:

A higher value of this indicator signifies an elevated risk of surface and groundwater depletion, intensified competition among users, and the degradation of environmental and ecological functions.

Units / Range

Percentage (%) / ranges between 0% to 100%

Representativeness

Temporal representativeness: Statistical values based on monthly data from 1980 to 2019 (calculated for each of the 12 months)
Spatial representativeness: Sub-basin

Calculation & Reference:

For details on the calculation methodology and the underlying references, please refer to the Water Security Compass Technical Note.