Permafrost degradation poses an increasingly serious threat of glacial lake outburst floodings (GLOFs) in the Tibetan Plateau. It is therefore of great practical significance to analyze the freeze-thaw state in moraine dams and associated impacts on dam stability. We simulated the soil temperature of the Longbasaba moraine dam based on the heat transfer module of COMSOL Multiphysics. The results show that the soil temperature of the moraine dam can be adequately simulated using the COMSOL Multiphysics heat transfer module and the simulated temperature values are generally consistent with the observed trends, yielding root mean square errors (RMSEs) less than 1.58 and Nash-Sutcliffe efficiency coefficients (NSEs) between 0.66 and 0.93. The average annual increase of the active layer depth was 0.026 m/a from 1959 to 2020. The buried ice inside the moraine dam was evidently melting and the maximum buried ice thawing depth under scenarios SSP1-2.6, SSP2-4.5, and SSP5-8.5 in CMIP6 (Coupled Model Intercomparison Project Phase 6) is expected to be 11.3 m, 18.4 m, and 23.5 m, respectively, by the end of the century, which indicates a continuous deterioration of the moraine dam stability.

The lower elevation limit for permafrost on the northern slopes of the Himalayas is considered to be 5,100-5,300 m above sea level (a.s.l.) (Gruber, 2012;Zou et al., 2017); and there are thousands of moraine-dammed lakes above this limit (