Navigating the energy-ecology-carbon nexus: A multi-objective reservoir operation framework for greener hydropower development

Study Region The Nirji Reservoir is located in the Nenjiang River Basin, Northeast China. Study Focus Navigating the energy–ecology–carbon nexus is a critical challenge for the sustainable development of hydropower under China’s dual-carbon strategy. The failure of carbon emission mitigation by traditional reservoir operations has led to a shift in reservoirs from being carbon sinks to carbon sources and the deterioration of ecological performance. To address this issue, this study proposes a hydropower generation–ecology–low-carbon coordinated multi-objective reservoir operation framework (HECC-RO) that integrates inflow forecasting, carbon-emission accounting, Pareto-based multi-objective optimization, and multi-criteria decision analysis to evaluate alternative operation schemes under different management preferences. New Hydrological Insights Results show that the proposed framework improves the balance among hydropower generation, ecological performance, and carbon reduction in the Nirji Reservoir. Relative to the current engineering-practice baseline, the Carbon-optimal scheme reduces carbon emissions by 29.6% and EcoDev by 85.9%, with only a 12.3% loss in hydropower generation, and CEI decreases to 115–125 g/kWh. These findings provide regional hydrological insight into how monthly operation of a large upstream control reservoir in the Nenjiang River Basin can better coordinate hydropower production, downstream flow regulation, and low-carbon performance.