Hydropower system in the Yarlung-Tsangpo Grand Canyon can mitigate flood disasters caused by climate change

Abstract The world’s largest diversion-type hydropower system will be created on the Yarlung-Tsangpo Grand Canyon. The canyon, a critical region for hydropower development and ecological conservation, faces challenges under climate change. Here we evaluate the water-energy-ecosystem nexus in this hydropower system using the Water and Energy Transfer Processes in Large River Basins model and the Non-Dominated Sorting Genetic Algorithm III model. Key findings reveal that reservoir operations with medium replenishment flow (1000 m³ s −1 ) during dry periods achieve an optimal balance among hydropower generation annually (2231 × 10 8 kWh), flood mitigation (peak clipping rate 22.8%), and minimal ecosystem impact (eco-index 0.45). Hydropower development stabilizes runoff regimes, enhances flood control capacity under climate scenarios (e.g., 29.2% peak reduction under Shared Socioeconomic Pathway 126), and mitigates downstream flood risks while supporting dry-season irrigation and navigation. Notably, under low-forcing climate change scenarios (Shared Socioeconomic Pathway 126), ecosystem stability is sustained primarily through the gradual and consistent replenishment of water resources from stabilized snowpack and glacial reserves. Transboundary cooperation is strengthened through adaptive reservoir management, ensuring energy security for China and flood protection for downstream nations. This integrated approach highlights the potential for harmonizing sustainable hydropower expansion with ecological and geopolitical resilience in international river basins.