Understanding multisector and transboundary trade-offs of hydropower expansion in the Mekong River basin

River systems sustain societies, economies, and ecosystems, yet their management is increasingly constrained by competing demands for energy production, food security, and environmental protection. The Mekong River basin exemplifies these tensions. Rapid hydropower expansion - over 160 dams have been built in recent decades, and hundreds more are planned - has profoundly altered one of the world’s most biodiverse and productive river systems, raising concerns over their cumulative impacts on sediment transport, aquatic ecosystems, greenhouse gas emissions, and regional livelihoods. Despite exstensive research on hydropower sustainability, basin-scale assessments that explicitly capture multi-sector interactions and transboundary trade-offs remain limited.

Here, we introduce an integrated modeling framework to evaluate the multisectoral consequences of alternative hydropower development portfolios across the entire Mekong Basin. The framework couples the large-scale hydrological model VIC-Res with a suite of sectoral impact models, enabling the joint assessment of five key dimensions: hydropower generation, reservoir greenhouse gas emissions, sediment connectivity, ecosystem alteration, and freshwater fishery productivity. This integrated setup allows the quantification of trade-offs and synergies both across sectors and national boundaries, providing a comprehensive basis for evaluating the sustainability and equity of hydropower development.

We apply the framework to a set of dam portfolios representing contrasting development pathways, spatial configurations, and management objectives. For each portfolio, we analyze how benefits and costs of hydropower development are distributed among Mekong countries and sectors, considering both basin-wide outcomes (e.g., the total energy production, sediment fluxes, and ecosystem health) and national-level indicators. By explicitly linking hydrological, ecological, and socio-economic processes, the framework captures feedbacks and dependencies that are typically overlooked in single-sector assessments.

Our results provide a powerful lens for exploring the boundaries of sustainable hydropower development. By jointly representing water, energy, ecosystem, and socio-economic interactions, the framework enables identification of development pathways that maintain the integrity of critical ecological functions and productive processes while meeting energy objectives. The analysis reveals how development choices can move the basin toward - or away from - sustainable and equitable operating trajectories. Ultimately, this work offers a transferable methodological foundation to support integrated, cooperative planning in the Mekong and other transboundary river basins worldwide.