Mapping the Social–Ecological Nexus to Determine System Properties That Maintain Sustainability and Productivity in Village Tank Cascade Systems of Sri Lanka

The social–ecological nexus (SEN) offers a framework to capture the complex and dynamic interactions and interdependencies between human communities and the natural systems that support them. This study analyzed the SENs within a village tank cascade system (VTCS), a social–ecological system (SES) located in the dry zone of Sri Lanka. The study adopted a participatory approach, combining fuzzy cognitive mapping (FCM) to determine key SES properties of the VTCS. The FCM process identified 49 nodes (elements) and 434 edges (connections) within the study landscape that contribute to system performance. Network graphs were generated using centrality metrics—degree, betweenness, and eigenvector centrality—to identify the most influential nodes and edges contributing to system sustainability and productivity. The study identified nine nodes as the most influential elements in the SEN which are critical for balancing trade-offs between sustainability and productivity in the VTCS. Three distinct clusters of elements influencing sustainability and productivity emerged from the SEN graph: (i) ecological cluster, (ii) social–ecological cluster, and (iii) social cluster. Understanding the role of SES elements and their positions in the SEN is crucial for identifying gaps within the system and informing tailored management interventions. These findings offer a theoretical basis for optimizing sustainability strategies aimed at enhancing the overall productivity and resilience of SES. Consequently, this approach exposes the complexities of the SEN, making it widely applicable to similar SESs globally.