Bridging Transboundary Rivers: Adressing Inequities through Operational Flexibility in Cooperative Basin Management

Transboundary river management involves the systematic and collaborative efforts of multiple nations sharing a river basin to ensure the sustainable and equitable use of water resources, support energy generation and food production, mitigate environmental impacts, and maintain the ecological balance of the shared hydrological system. Here, we introduce a novel framework for integrating equity considerations into the systemwide optimization of transboundary river management to explicitly address how energy and water supply risks can asymmetrically fall on riparian nations. In contrast to approaches that rely on game theory and hydro-economic modeling to design stable, yet static, compensatory schemes under cooperative management, our framework explores the potential for dynamic operational flexibility to achieve equitable and resilient use of a basin's water resources within existing and planned infrastructure. Our framework relies on multi-objective optimization at the basin scale to generate operational alternatives reflecting incremental degrees of inequality aversion in hydropower generation at the country scale. This is achieved through fully coordinated reservoir operations that adaptively allocate flow and storage in response to changing hydrological conditions, ensuring a fair distribution of benefits and tradeoffs among riparian nations as measured by the Atkinson inequality index. We demonstrate the approach through a case study of the Zambezi River watercourse, where planned dams in the upper basin (managed by Zambia and Zimbabwe) and the lower basin (managed by Mozambique) would double the basin's total hydropower capacity. We show that incorporating equity produces more hydrologically robust strategies that more effectively compromise on tradeoffs between hydropower generation, irrigation demands, and environmental flows at the country level. The findings thus demonstrate the potential of using more dynamic approaches to transboundary water resource management in an era of increasing climate uncertainty.