The water-energy-food-ecosystems nexus: concepts and application to address water scarcity in Northern Italy

The rapid socio-economic development experienced by the Global North since the 1950s has come with consequences for the Earth System’s stability and resilience, alongside an inequitable distribution of wealth and resources. The 2030 Agenda for Sustainable Development provides a global framework to address development gaps while safeguarding the Earth System upon which future generations depend. Yet, achieving the Agenda in all its targets is challenged by the interconnectedness of natural systems – climate, oceans, freshwater, ecosystems – and of development goals. Adopting systemic and holistic approaches to managing human-nature relationships is thus increasingly urgent in a complex and interconnected world. The Water-Energy-Food (WEF) Nexus is a novel approach focusing on the interdependencies between water, energy and food sectors and aiming at informing a coherent multi-sectoral governance. As an emerging topic in the sustainable development agenda, WEF Nexus research is still in an exploratory and diverging phase, with limited consensus on its definition, methods and applications to real-world problems. In this thesis I advance existing research on the WEF Nexus by exploring its concept in relation to the integration of Ecosystems, i.e. the so-called WEF-Ecosystems (WEFE) Nexus, and by applying it to a case study of water resources allocations and management in a mountainous catchment of the Po River basin in Northern Italy. The thesis is structured in four main chapters and stems from the results of a systemic literature review undertaken on WEFE Nexus research in the Mediterranean, a region of the world facing increasing water, food, energy security issues. The conceptual, methodological and operationalisation gaps identified in the review (Chapter 2) shape the research questions and methods developed in subsequent chapters. On a conceptual level, the literature review highlights a multiplicity of semantics and conceptual frameworks used to represent nature in the Nexus through the concepts of ‘environment’, ‘ecosystems’, ‘biodiversity’ and ‘ecosystem services’. I thus initiated and co-coordinated a collaborative process of knowledge creation combining literature analysis and elicitation of experts’ opinion to critically examine existing perspectives on the integration of nature in the Nexus (Chapter 3). We argue that terms like ‘environment’, ‘ecosystem services’, and ‘ecosystems’ reflect the roles attributed to nature in the Nexus, and we emphasise the need for Nexus assessment to move beyond an optimisation of the environmental component towards a more holistic consideration of the complex human-nature dynamics within and beyond the Nexus sectors. In Chapter 4, I apply these conceptual insights to explore WEFE Nexus interlinkages through a Social-Ecological System (SES) lens in the Torrente Orco catchment, a sub-basin of the River Po in Northern Italy. I use the Causal Loop Diagram, a systems thinking tool, and the Network of Action Situation, a method originating in the theory of SES, to identify interdependencies between social-ecological processes across WEFE Nexus sectors and to characterise sectoral and cross-sectoral governance processes involved in addressing water scarcity. Trade-offs and synergies between hydropower production, irrigation, drinking water supply and ecological flows are shown to be the result of the impacts of climate change, the socio-economic development of water uses, and the decisions taken on water allocation at different levels. In Chapter 5, I quantify the magnitude and seasonality of such trade-offs by simulating hydrological processes and water allocation strategies in the Torrente Orco catchment over the period 2011 – 2022. I show that trade-offs between hydropower production and irrigation occur mostly late in the irrigation season (July-August) and that the relative upstream-downstream positioning of irrigation consortia can significantly influence the frequency and magnitude of water scarcity and the impact of stricter ecological flows regulations. Overall, the thesis demonstrates that notwithstanding the conceptual and operationalisation challenges of the WEFE Nexus, its application as a systemic and integrated approach can generate novel insights for a more sustainable and cross-sectoral management of water resources.