Increasing glacial lake outburst flood hazard on the eastern Tibetan Plateau and implications for the Sichuan–Tibet Railway

Abstract Glacial lake outburst floods (GLOFs) are a severe natural hazard on the eastern Tibetan Plateau, posing a risk to infrastructure safety (e.g. the Sichuan–Tibet Railway) and regional socioeconomic development. However, previous GLOF studies often neglected GLOFs’ return periods when evaluating their magnitudes. In this study, we developed a probabilistic modeling framework to quantify the peak discharges and flood volumes of potential GLOFs with return periods ranging from 10 to 500 years for the eastern Tibetan Plateau with over 11 000 glacial lakes. The results indicate that the GLOF peak discharge increases from 0.5 × 10 3 m 3 s −1 at a 10 year return period to over ∼8.6 × 10 3 m 3 s −1 at a 500 year return period, whereas the flood volume increases from ∼1.42 × 10 6 m 3 to ∼20.17 × 10 6 m 3 . Future climate change will likely increase the GLOF magnitude, with peak discharge (100 year return period) increasing from ∼3.3 × 10 3 m 3 s −1 in 2015 to ∼3.8 × 10 3 m 3 s −1 in 2100 under the RCP8.5. We further evaluated the GLOF magnitude along the Sichuan–Tibet Railway and identified railway segments crossing the Yarlung Zangbo, Salween, and Jinsha rivers as high hazard areas, where the projected peak discharge exceeded ∼2.5 × 10 3 m 3 s −1 and flood volume surpassed ∼9.1 × 10 6 m 3 in 2100 under RCP8.5. These results underscore the urgent need to integrate GLOF hazards into infrastructure design and enhance the predictive capacity for potential GLOF impacts on river ecosystems, water quality and landscape evolution.