Advancing water footprint assessments: Combining the impacts of water pollution and scarcity

Several water footprint indicators have been developed to curb freshwater stress. Volumetric footprints support water allocation decisions and strive to increase water productivity in all sectors. In contrast, impact-oriented footprints are used to minimize the impacts of water use on human health, ecosystems, and freshwater resources. Efforts to combine both perspectives in a harmonized framework have been undertaken, but common challenges remain, such as pollu-tion and ecosystems impacts modelling. To address these knowledge gaps, we build upon a water footprint assessment framework proposed at conceptual level to expand and operationalize relevant features. We propose two regionalized indicators, namely the water biodiversity footprint and the water resource footprint, that aggregate all impacts from toxic chemicals, nutrients, and water scarcity. The frst impact indicator represents the impacts on freshwater ecosys-tems. The second one models the competition for freshwater resources and its consequences on freshwater availability. As part of the framework, we complement the two indicators with a sustainability assessment representing the levels above which ecological and human freshwater needs are no longer sustained. We test our approach assessing the sus-tainability of water use in the European Union in 2010. Water stress hampers 15 % of domestic, agricultural and indus -trial water demand, mainly due to irrigation and pesticide emissions in southern Europe. Moreover, damage to the freshwater ecosystems is widespread and mostly resulting from chemical emissions from industry. Approximately 5 % of the area is exceeding the regional sustainability limits for ecosystems and human water requirements altogether. Concerted efforts from all sectors are needed to reduce the impacts of emissions and water consumption under the sus-tainability limits. These advances are considered an important step toward the harmonization of volumetric and impact-oriented approaches to achieve consistent and holistic water footprinting as well as contributing to strengthen the pol-icy relevance of water footprint assessments.

Automated summary

Several water footprint indicators have been developed to address the issues of freshwater stress. Volumetric footprints focus on water allocation and productivity, while impact-oriented footprints aim to minimize the negative effects of water use on human health, ecosystems, and freshwater resources. However, challenges in combining these perspectives remain, such as pollution and ecosystem impact modeling. To bridge these gaps, a water footprint assessment framework is proposed, incorporating regionalized indicators for water biodiversity and water resource, and complemented with a sustainability assessment. The framework is tested on the water use sustainability in the European Union, revealing the need for concerted efforts in reducing the impacts of emissions and water consumption.