On the use of Participatory System Dynamics Modelling for WEF Nexus management: Hints from two case studies in the Mediterranean region

The security of natural resources is increasingly threatened by multiple pressures that range from climate change impacts to socio-economic conditions, and requires a coordinated action by several practitioners and policy-makers. The concept of Nexus has therefore gained increasing attention in recent scientific literature, as it aims to achieve natural resources security in a holistic and integrated way; however, it has still been limitedly put into practice. Different sectors can be included in Nexus studies, and in the present work reference is made to a rather innovative combination which includes Water, Food and Ecosystems. The present paper proposes the use of Participatory System Dynamics Modelling (PSDM) techniques for an improved Nexus understanding, analysis and management to support policy- and decision-makers. More specifically, we argue that Stock and Flow Diagrams (SFDs), besides providing an improved understanding of the complex interactions and interdependencies in Nexus systems, can also help evaluate multiple policies and solutions for Nexus management based on the use of Sensitivity Analysis and on a what-if Scenario Analysis. In this process, the involvement of stakeholders throughout the modelling phases (from model structure building to scenario selection and analysis) guarantees the inclusion of local knowledge as well as the relevance and ownership of results. Reference is made to the experience in a couple of case studies, namely the Pinios River Basin and the Greater Chania Area (both in Greece but characterized by socio-environmental conditions typical of the whole Mediterranean Area), where Nexus management is central to guaranteeing a sustainable future.