Loss of water purification

Loss of water purification

Rivers and the land around them clean water for free: they take up nitrogen before it reaches the water a site draws. When river nitrogen rises, a site that relies on that water has to treat it itself. Resilience books that cost as a Business interruption loss, against revenue only.

What the map shows

• Today: Water Purification Degradation (2015). The routed river nitrogen concentration at the site, on a scale from pre-industrial river nitrogen (0.3 mg N/L, 0 points) to the EU Nitrates Directive limit (11.3 mg N/L, 100 points). The concentration is calibrated on French river nitrate measurements.
• Projected: Water Purification Loss layers for SSP1, SSP2-4.5 and SSP3, at 2035, 2050 and 2080. The change in river nitrogen follows the IMAGE-GNM river nitrogen load. A small contamination term (soil metals, pesticides, PFAS) is added on top.

This service has its own layers, so it does not go through the natural assets.

How the loss is computed

The degradation D, between 0 and 1, is read from the layer at the site. The dependency is the ENCORE rating of the site's activity, read as (rating − 1) / 4. The loss is D × min(dependency, k) × revenue, where k is the yearly cost of treating the water, as a share of revenue. k exists for factories and powerhouses, R&D labs, mining, oil and gas (land), and high- and low-input agriculture. Its values are provisional placeholders. Other site types keep D × dependency. See Nature risks and Shock layers.

Sources

• Chaplin-Kramer et al. (2019), Science 366:255, InVEST NDR outputs (Zenodo 21249617). CC BY 4.0.
• IMAGE-GNM nutrient model (river N). Licence not confirmed.
• HydroSHEDS (Lehner & Grill 2013); TerraClimate (Abatzoglou et al. 2018). HydroSHEDS: HydroSHEDS v1 licence (WWF), statement below. TerraClimate: CC0 1.0.
• Naïades river quality data (OFB / Agences de l'eau, via Hub'Eau). Licence Ouverte Etalab 2.0.
• Hou et al. (2025), Science; Tang et al. (2021), Nature Geoscience; PFAS Data Hub (CNRS, 2026); Le Monde (2024), "300 contaminants dans nos nappes", data.gouv.fr, from ADES. Hou et al., Tang et al., PFAS Data Hub and Le Monde / ADES: Licence not confirmed.
• Ceiling after the EU Nitrates Directive; the Dodds et al. (1998) threshold is a control read only
• ENCORE 2024 (Global Canopy, UNEP FI, UNEP-WCMC): dependency ratings. CC BY-SA 4.0.

HydroSHEDS statement, as its licence requires:

This product Darwin incorporates data from the HydroSHEDS version 1 database which is © World Wildlife Fund, Inc. (2006-2022) and has been used herein under license. WWF has not evaluated the data as altered and incorporated within Darwin, and therefore gives no warranty regarding its accuracy, completeness, currency or suitability for any particular purpose. Portions of the HydroSHEDS v1 database incorporate data which are the intellectual property rights of © USGS (2006-2008), NASA (2000-2005), ESRI (1992-1998), CIAT (2004-2006), UNEP-WCMC (1993), WWF (2004), Commonwealth of Australia (2007), and Her Royal Majesty and the British Crown and are used under license. The HydroSHEDS v1 database and more information are available at https://www.hydrosheds.org.

Limits

• The calibration is fitted on France and applied worldwide without a check elsewhere. Regional biases remain inside France itself.
• Where the routed nitrogen is missing (north of about 60° N, runoff under 10 mm a year), the layer has no level today, and the projected loss holds the contamination term alone.
• 2080 holds the 2050 state.
• The weight of the contamination term is provisional.