Water Footprint Network Approach Linked to Strategic Crop Value Chains in Tunisia

Abstract

This methodological note presents an integrated framework for assessing the water footprint of strategic crop value chains under conditions of increasing water scarcity, with a particular focus on Tunisia. Agriculture is the largest consumer of freshwater resources in the country, while climate variability, recurrent droughts, and competing demands place growing pressure on limited surface and groundwater supplies. To support informed water management and sustainable agricultural development, the study combines two complementary approaches: a volumetric water footprint assessment based on the Stepwise Accumulation Approach and a water footprint impact assessment aligned with ISO 14046 and Life Cycle Assessment (LCA) principles. The first approach quantifies blue, green, and grey water use at each stage of the value chain and links water consumption to both physical and economic water productivity. The second approach evaluates the potential environmental impacts of water use, including water scarcity, eutrophication, ecotoxicity, and human toxicity, using established characterization methods such as AWARE, ReCiPe, and USEtox. Case studies from the literature illustrate how water footprints accumulate along value chains and identify irrigation and processing stages as critical hotspots. The results demonstrate that integrating volumetric and impact-based approaches provides a more comprehensive understanding of water use, productivity, and environmental risk than either method alone. While volumetric indicators support efficiency and water allocation decisions, impact-based metrics contextualize water use within local environmental constraints. Despite data limitations and methodological challenges, the proposed framework offers a robust and adaptable tool to inform policy, guide resource allocation, and support sustainability strategies in water-scarce agricultural systems.