Coupling Causal-loop of System Dynamics and Centrality of Network Analysis to Identify Key Elements for Water-energy-food Nexus

Water, energy, and food sectors are strongly interconnected. The interconnection, namely water-energy-food nexus, is essentially a complex network that is constituted by a large number of system elements (nodes) and their connections (edges). Identification of the hub nodes i.e., the key elements of the network is a critical step in simulating the water-energy-food nexus. This study coupled System Dynamics modeling and Network Analysis (NA) to identify the key elements of the water-energy-food nexus. First, the system elements of the nexus and their interconnections are qualitatively analyzed using the causal-loop diagram of the System Dynamics model. The diagram is then transferred as a network in which the system elements and associated connections are treated as nodes and edges of the network, respectively. The NA is then applied to the network, and attributes of the nodes such as degree, betweenness, and closeness centrality are investigated. The importance of the elements is assigned based on those attributes valuations, and the key system elements are identified using multi-attribute decision approach. Two cases concerning different scales(household scale and global scale) of water-energy-food nexus are used for demonstrating the effectiveness of the proposed approach. The identification of key system elements is critical for understanding the working mechanism of the water-energy-food nexus. It also helps to reduce the dimensionality of the nexus due to a prioritized variable list.