Coordination between the water, energy, food and environment sectors is fraught with difficulties even at the national level, but the complexity increases substantially in transboundary basins where the impacts spread from one country to another. The “nexus approach” to managing interlinked resources has emerged as a way to enhance water, energy and food security by increasing efficiency, reducing trade-offs, building synergies and improving governance, while protecting ecosystems.

This publication contains the results of nexus assessments that have been carried out in the framework of the UNECE Water Convention’s programme of work for 2013–2015 in specific basin contexts: the Alazani/Ganykh in the Caucasus, the Sava in South- Eastern Europe and the Syr Darya in Central Asia. The assessments aimed to foster transboundary cooperation by identifying intersectoral synergies and determining measures that could alleviate tensions related to the multiple needs of the riparian countries for common resources. The process looked to generate relevant information to support decision-making, and it engaged diverse expertise and key actors in the basins.

The nexus assessments describe the characteristics of the resources of water, food and land, energy and ecosystem services, and their governance. Graphics illustrate the interlinkages identified. Climate change and socioeconomic drivers, and their effects on intersectoral dynamics, are also considered. Finally, a broad range of beneficial response actions are outlined. Such solutions to the nexus span institutions, information, instruments, infrastructure as well as international coordination and cooperation.

The methodology employed was developed specifically for assessing the nexus in transboundary basins with multi-disciplinary expertise and was applied with support from various partner organizations. It is applicable to diverse transboundary basins and aquifers, and its use is illustrated step-by-step. Lessons learned are shared for the benefit of those who wish to embark on a similar exercise.