Water depletion (Aqueduct 4.0)
This layer measures baseline water depletion: how much of an area's renewable water is permanently consumed — that is, withdrawn and not returned — relative to what is av
Source: WRI Aqueduct 4.0 Year: 2023 Category: Transition risks · Overexploitation Coverage: Global Format: Boundary polygons (hydrological catchments) Used in risk analysis: No (contextual layer; not used in materiality scoring)
What it shows
This layer measures baseline water depletion: how much of an area's renewable water is permanently consumed — that is, withdrawn and not returned — relative to what is available. Where depletion is high, water is being drawn down faster than it is replenished, reducing what remains for downstream users and for nature.
How it is built
Baseline water depletion is the ratio of total water consumption to available renewable supplies in each catchment. Consumption combines domestic, industrial, irrigation and livestock consumptive uses — only the water that is actually used up, not water that is withdrawn and returned. Available supply accounts for how upstream consumption and large dams reduce water reaching downstream areas. It is closely related to baseline water stress, but uses consumptive withdrawal only rather than total demand. Values come from WRI Aqueduct 4.0 and are provided for hydrological catchment areas worldwide.
How to read it
Higher values indicate a larger net drawdown of the local water supply and reduced availability for downstream users; lower values indicate that consumption is small relative to renewable supply. A site is assessed by the depletion level of the basin it sits in.
Class thresholds
The underlying quantity is a physical ratio: baseline water depletion — total consumptive water use divided by available renewable supply, expressed as a percentage (%). Each catchment's value places it in one of Aqueduct's ordinal classes:
| Class | Water depletion (% of renewable supply) |
|---|---|
| Low | < 5% |
| Low – Medium | 5 – 25% |
| Medium – High | 25 – 50% |
| High | 50 – 75% |
| Extremely High | > 75% |
A separate "Arid and Low Water Use" category covers catchments with very little water and very low use. A site is flagged on the Overexploitation dimension when its catchment falls in the High class or above (i.e. depletion above 50%).
How these thresholds were set. The class split follows the WRI Aqueduct 4.0 methodology — the standard Aqueduct water-depletion bins (<5% / 5–25% / 25–50% / 50–75% / >75%). It is not a Darwin in-house classification.
Reference: WRI Aqueduct 4.0 — wri.org/aqueduct.
Source
WRI Aqueduct 4.0 baseline water depletion (World Resources Institute). See doi.org/10.46830/writn.23.00061.
Comparison with the WWF Risk Filter Suite
This layer maps to BRF S1_1 Water Availability and WRF B1_1 Water Depletion, and belongs to the same family as WWF's depletion input. The alignment is direct.
Legend
Symbolised field: Baseline water depletion category
| Value (Baseline water depletion category) | Label | Colour |
|---|---|---|
| -1 | No Data | #d3d3d3 |
| 0 | Arid and Low Water Use | #74afd1 |
| 1 | Low (<5%) | #aac7d8 |
| 2 | Low - Medium (5-25%) | #dededd |
| 3 | Medium - High (25-50%) | #f8ab95 |
| 4 | High (50-75%) | #f27454 |
| Extremely High (>75%) | #ed2924 |
Generated from darwin/layers/layer-water-depletion-aqueduct-4-0.toml and risk_indicator_pairs.toml (develop).