Freshwater Quantity Overshoot
This layer flags sub-catchments where freshwater is being used beyond what the local water system can sustainably provide.
Category: Transition risks · Overexploitation Coverage: Global Format: Boundary polygons (sub-catchments) Used in risk analysis: Yes — gates Overexploitation
What it shows
This layer flags sub-catchments where freshwater is being used beyond what the local water system can sustainably provide. It identifies areas of water overuse, which is central to assessing water-related dependencies, transition risk and alignment with science-based water targets.
How it is built
The layer is based on the Science Based Targets Network's Freshwater Quantity Target (version 2), developed by Hogeboom and colleagues (2025). For each sub-catchment, annual blue-water consumption (water drawn from rivers, lakes and aquifers) is compared against a sustainable cap. Where consumption exceeds that cap — an overshoot greater than zero — the sub-catchment is flagged. The assessment is carried out over global sub-catchment units.
How to read it
This is a flag-based layer rather than a graded score: a sub-catchment is either in overshoot (sustainable freshwater use exceeded) or it is not. A site falling within a flagged sub-catchment should be treated as exposed to freshwater-quantity stress and reviewed further.
Source
SBTN Freshwater Quantity Target v2 (2025); Hogeboom, Su, Prunes, Dilks and Townsend (2025). Licensed under CC BY 4.0.
Comparison with the WWF Risk Filter Suite
This contributes to WWF Biodiversity Risk Filter indicator S1_1 Water Availability, specifically its freshwater-quantity dimension. It is aligned with the WWF water-availability family and adds a science-based-targets view of where freshwater use exceeds sustainable limits.
Risk analysis
A site is flagged on a dimension by combining a proximity trigger (this layer) with an activity trigger (the entity's ENCORE pressure/service). Proximity only → Potentially material; proximity and the matching ENCORE pressure/service is material → Very material; neither → Not material.
| Dimension | ENCORE service / pressure | Proximity trigger (this layer) | Activity trigger (entity) |
|---|---|---|---|
| Overexploitation | Volume of water use | Site overlaps / is near the feature | “FreshwaterConsumption” pressure ≥ 10000; “Volume of water use” pressure ≥ 4 |
Legend
Symbolised field: Water consumption reduction target
| Class | Colour |
|---|---|
| No overshoot | #fff5b0 |
| Low (1–25%) | #ffd966 |
| Medium (26–50%) | #ffae42 |
| High (51–75%) | #ff8000 |
| Very high (76–100%) | #cc4400 |
Generated from darwin/layers/layer-freshwater-quantity-overshoot.toml and risk_indicator_pairs.toml (develop).