Drought and water stress

Drought and water stress

Where many users compete for limited water, a site can run short of what it needs to cool, process or grow. The site keeps standing, but it produces less. Drought and water stress prices Business interruption only (% of annual revenue). It measures chronic water stress, not a dated drought event.

What the map shows

• Today: the WRI Aqueduct 4.0 baseline water stress per catchment: the share of renewable water already claimed by domestic, industrial, irrigation and livestock uses (sheet).
• Projected: the map does not move. Aqueduct publishes its future scores as columns of the same catchment table, not as separate maps, so there is nothing for the selector to switch. The engine reads those projected scores at 2035, 2050 and 2080 to compute the projected loss.

How the loss is computed

The engine reads the catchment's water-stress score (0 to 5) at the site's point. A shortfall probability per score, times a conditional production loss scaled by the water dependence of the site type, gives the annual loss. The per-score rates are anchors read continuously between integer scores. Where a site reports its water use in m³ per year, a quantitative water criticality replaces the type-based dependence. The hazard is tagged Proposal. See Damage functions: Drought / water stress and Climate risks.

Drought is measured as a slow drift: the Exclude slow-drift baselines switch sets its baseline to zero so that only the change counts.

Sources

• WRI Aqueduct 4.0, baseline water stress and projections (doi:10.46830/writn.23.00061). CC BY 4.0.
• Damage curve: FAO-33 yield-response form and van Vliet (2016) cooling-water dependence.

Limits

• The score-to-shortfall bridge, the per-score loss rates and the dependence tiers are Darwin proposals.
• The Aqueduct score carries no drought index, no return period and no event. Reading it as an acute drought overstates the coverage.
• An arid catchment with little water use scores 5, the same as an extremely stressed one.
• The loss grade on business interruption is withheld, because the figure is not considered plausible enough yet.