Water Scarcity - Baseline Water Stress

Baseline Water Stress estimates how much of the available freshwater in a river basin is used (consumption & withdrawal) by homes, industries, irrigation and livestock.

Overview

Data Type	Modelled data based on a global hydrological model
Source	World Resource Institute
Spatial Resolution	Spatially explicit to river basins (HydroBASINS level 6)
Temporal Resolution	Based on data for the years 1979-2019. Last update from 2023.
Interpretation	The Baseline Water Stress indicator translates the raw value (%) into a 0-10 score based thresholds established by scientific literature.
Concern Levels	Very Low = Score 0 - 2 Low = Score 2 - 4 Moderate = Score 4 - 6 High = Score 6 - 8 Very High = 8 - 10
Framework Relevance	Baseline Water Stress is relevant under CSRD (ESRS E2 and ESRS E3) as well as under TNFD and SBTN.

Detailed Specifications

Explanation

Baseline Water Stress measures the ratio of total water demand to available renewable surface and groundwater supplies. Water demand includes estimated water consumption and withdrawal through domestic, industrial, irrigation, and livestock uses. The percentage value indicates the share of renewable freshwater that is withdrawn or consumed throughout the year. Higher values indicate thus more competition among water users. Values above 40% are considered high levels of water stress. The indicator is an output of the global hydrological model PCRaster Global Water Balance Model (PCR-GLOBWB 2) developed at Utrecht University.

Transformation & Interpretation

The raw Baseline Water Stress values are converted into a 0-5 scale based on threshold values developed by Gassert et al. (2015) using the following logarithmic transformation:

Where r is the raw indicator value and score is the resulting indicator score between 0 and 5. The score is scaled to a range from 0 to 10 by multiplying the initial value by the factor 2.

Raw Values (%)	Score	Concern Level
≤ 10%	0 - 2	Very Low
10% - 20%	2 - 4	Low
20% - 40%	4 - 6	Moderate
40% - 80%	6 - 8	High
> 80%	8 - 10	Very High

Source

This Baseline Water Stress value is sourced from Camargo et al. (2023). The underlying data stems from Hofste et al. (2019).

Date of publication

2023

Confidence & Accuracy

Medium (best available at global scale). The Baseline Water Stress indicator is based on a global hydrological model and tailored to large-scale comparison of water stress levels. The indicator might occasionally fail to accurately estimate water stress at the local scale. Nevertheless, Baseline Water Stress is widely used and accepted in practice, explicitly referenced TNFD guidelines and explicitly required for science-based target setting under SBTN.

Relevance under CSRD

CSRD requires companies to identify operational sites situated in areas of water risk, incl. areas of high-water stress. The baseline water stress indicator specifically is relevant to the following ESRS requirements:

ESRS Article	Disclosure or application requirement
ESRS E2 AR 23 (c)	percentage of emissions of pollutants to water and soil occurring in areas at water risk, including areas of high-water stress
ESRS E3 DR 12 (c)	commitment to reduce material water consumption in areas at water risk
ESRS E3 DR 13	policy for sites located in an area of high-water stress
ESRS E3 DR 19	actions and resources in relation to areas at water risk, including areas of high-water stress
ESRS E3 DR 23 (a)	impacts, risks and opportunities related to areas at water risk, including improvement of the water quality
ESRS E3 DR 23 (c)	reduction targets for water consumption, in areas at water risk, including areas of high water-stress
ESRS E3 DR 28 (b)	total water consumption in m3 in areas at water risk, including areas of high-water stress
ESRS E3 AR 5 (b)	sites located in areas at water risk, including areas of high-water stress
ESRS E3 AR 13 (b)	risks including water quantity (water scarcity, water stress), water quality (...)

CSRD requires companies to consider and describe the data used in their analysis (ESRS E4 AR 27). For convenience, here a description of for the relevant criteria:

ESRS Data Criteria	Comment
(a) methodology, reason for selection, assumptions, limitations & uncertainties	Methodology: Baseline Water Stress is estimated based on a global hydrological model (PCR-GLOBWB 2). Reason for selection: The indicator has been selected to assess the level of water scarcity. The selected metric is science-based, peer-reviewed, widely used and specifically endorsed by guidelines such as TNFD and SBTN. Assumptions: The indicator is model based and incorporates several assumptions detailed in Hofste et al. (2019). Limitations & uncertainties: The Baseline Water Stress indicator is based on a global hydrological model and tailored to large-scale comparison of water stress levels. The indicator might occasionally fail to accurately estimate water stress at the local scale.
(b) scope of metric	The Baseline Water Stress indicator is applied at site level.
(c) biodiversity component of metric	The Baseline Water Stress is an ecosystem-level nature indicator. It assesses ecosystem structure by providing an indicator for the physical state of the ecosystem.
(d) covered geographies	The Baseline Water Stress indicator has global coverage.
(e) integration of ecological thresholds	The Baseline Water Stress indicator relates to the planetary boundaries of freshwater change.
(f) frequency of monitoring, baseline condition and period	The Baseline Water Stress indicator is based on data for the years 1979-2019 with the last update in 2023.
(g) data type (primary, secondary, modelled, expert judgement	The Baseline Water Stress indicator relies on modelled data, based on a global hydrological model (PCR-GLOBWB 2).

Relevance under TNFD

The Baseline Water Stress indicator is a suitable indicator to estimate water availability under the criteria of Physical Water Risk within TNFD’s LOCATE step.

Relevance under SBTN

The Baseline Water Stress indicator represents one out of three water availability indicators explicitly required to use as a pressure-sensitive State of Nature indicator in SBTN Step 1: Assess and Step 2: Interpret & Prioritize.

SBTN Data & Tool Criteria	Evaluation	Comment
Relevance	✅	PGP contributes to the pressure-sensitive state of nature metric water pollution required by SBTN methodology.
Representative	✅	PGP data represents a close fit with the SBTN characterization of the water pollution issue and is appropriate to be applied under Step 1 & 2.
Spatial and Temporal Resolution	✅	The PGP indicator is provided at the spatial resolution of level 4 of Hydrological sub-basin (HydroBASINS 4). The PGP indicator is based on N and P data from thousands of sites sampled worldwide between 1990 and 2016.
Stability and Preservation	✅	PGP data sets are likely to be maintained and preserved long-term as they are provided by SBTN.
Accessibility	✅	The PGP data is accessible online.
Interpretability	✅	The PGP indicator is sufficiently interpretable and generates an appropriate input for the SBTN methodology.
Coverage	✅	PGP has global coverage.
Authoritative and Accurate	✅	PGP data is science-based, peer-reviewed and explicitly required by SBTN.