Design of water reuse scenarios based on risk assessment for sustainable agricultural water managment

This PhD research advances a site-specific, risk-based approach to agricultural water reuse under growing water scarcity and climate pressure, aligned with Regulation (EU) 2020/741 and extending management beyond the wastewater treatment plant to distribution networks and on-field application. Four complementary contributions support this objective. (i) It quantifies the impact of treated wastewater on irrigation water quality, providing an evidence base to determine whether TWW discharge leads to deterioration or, under certain hydraulic and operational conditions, can support fertigation without compromising safety. (ii) It develops an operational risk management framework specifically designed for distribution and irrigation systems, structuring system description, hazard and exposure analysis, risk evaluation, preventive measures, and adaptive monitoring for Risk Management Plans. (iii) It introduces a semi-quantitative environmental risk assessment tailored to agricultural reuse, integrating likelihood and magnitude of impact within a reproducible, regulation-linked structure that considers receiving compartments downstream of the point of compliance. (iv) It operationalizes the multi-barrier principle through an attribution matrix that links quality classes (A–D), crop–irrigation configurations, and barrier equivalents into practical scenarios at district and field scales. Collectively, these developments enable the risk-based design of water-reuse scenarios for real agricultural water reuse systems. They align health and environmental protection with agronomic needs within a One Health and WEFE Nexus perspective, thereby strengthening decision-making in European irrigation contexts. They also provide actionable implications for EU policy implementation of Regulation (EU) 2020/741, including the integration of indirect reuse, network-based monitoring, and transparent accreditation of multi-barrier equivalence.