New insights on the 2020 Jinwuco glacial lake outburst flood: considering ice content within the moraine dam

Climate warming has accelerated the expansion of glacial lakes across the Tibetan Plateau, thereby increasing the risk of glacial lake outburst floods (GLOFs). Although buried ice may exist within moraine dams, its influence on moraine-dam breaching remains poorly understood. To address this gap, we investigate the 26 June 2020 Jinwuco outburst in Tibet, using remote sensing, field surveys, and a thermo-mechanical model to assess how ice content within moraine dam affects breaching. The area of Jinwuco increased by 74.5% between 1987 and 2020, and field surveys confirmed the presence of buried ice within the moraine dam. Numerical simulations reveal that the outburst hydrograph exhibits a multi-peak pattern, and that the breaching process consists of a surge-induced erosion stage followed by a normal overflow erosion stage. Buried ice influences peak discharge: with 40% ice content, the peak discharge reaches 5147 m³/s, which is 41% higher than that under ice-free conditions and results in a substantially larger inundation extent. These findings quantitatively demonstrate the regulatory role of ice content in moraine dam breaching. Grounded in thermo-mechanical principles governing rock–ice collapse and motion, these findings also provide a scientific basis for hazard assessment and disaster mitigation in cold, high-altitude regions.