Water Footprint Assessment in Tomato Production: Strengths, Limitations and Complementarity of WFN and LCA-Based Approaches

Freshwater scarcity is an increasing concern for agricultural systems, making water footprint (WF) assessment an important tool for evaluating water use in crop production and supporting sustainable water resource management. Two main methodological approaches are widely used: the water footprint network (WFN) framework and Life Cycle Assessment (LCA)-based approaches. This review synthesizes 27 peer-reviewed studies that use tomato production as a representative case study to compare the two approaches across methodological frameworks, geographical contexts, production systems, system boundaries, functional units, and research objectives. The reviewed studies revealed substantial methodological heterogeneity, with WFN representing the predominant approach, whereas LCA-based applications remained comparatively limited. WFN was primarily applied to quantify water use and identify water-use hotspots, whereas LCA-based approaches focused on evaluating the potential environmental impacts of water consumption under local water-scarcity conditions. The review also highlights the ongoing debate surrounding scarcity-weighted indicators and the interpretation of water footprint results. Reported water footprint values varied considerably due to differences in climate, irrigation management, crop productivity, system boundaries, and methodological assumptions, particularly in the calculation of gray water footprint. Overall, the findings indicate that WFN and LCA-based approaches provide complementary perspectives on freshwater sustainability. Their combined application can support more comprehensive water assessments and better-informed decision-making in agricultural systems, while greater methodological harmonization is needed to improve the comparability of future studies.