A Systematic Review of Methodological Tools for Evaluating the Water, Energy, Food, and One Health Nexus in Transboundary Water Basins

Water plays a vital role in human socioeconomic development and overall well-being, making its effective management essential in achieving the Sustainable Development Goals. The close interlinkage between water, other environmental resources, and socioeconomic development have prompted the emergence and adoption of holistic and trans-sectoral concepts such as integrated water resources management and, more recently, the resource nexus. However, even such holistic approaches often exclude the one health approach, particularly at the transboundary water basins (TWBs), which not only dominate 40% of the earth but are vital in environmental and human sustainability. This review aimed to understand, evaluate, and compare assessment tools for water, energy, food, and one health (WEF + H) nexus management in TWBs. The review applied the systematic review guidelines for articles published in the Scopus database. The inclusion criteria encompassed English-language articles featuring case studies, meta-studies, or review articles with no less than three nexus resources. The review categorized the article based on criteria that focused on identifying tools capable of analyzing scenarios and policies for WEF + H in TWBs and their accessibility and easiness of implementation in case studies. Of the eighteen analyzed tools, 13 (72%) had limitations in their application at various geographical scales. Additionally, they could not integrate one health into the nexus or analyze policies through running scenarios. On the contrary, the Bayesian networks, system dynamics, agent-based models, life-cycle assessments, and input-output tools were highly accessible for efficiently conducting scenario-based WEF + H nexus assessments in TWBs.