Identification of asynchronous overtopping hazard patterns of glacial lakes in the Yarlung Tsangpo Basin

The Yarlung Tsangpo Basin, situated on the southern Tibetan Plateau of southwestern China, represents a transboundary basin within the Third Pole region. Using multisource remote sensing, DEM, and meteorological data from 1990 to 2023, this study investigates the phased expansion processes of glacial lakes with areas ≥ 0.02 km 2 . It identifies the asynchronous response patterns of glacial lakes across different elevation zones to climate change and quantifies the lag time (Δt) between climate change and the accelerated expansion of glacial lakes. An overtopping hazard assessment framework integrating topographic potential energy and climate response characteristics is developed to identify glacial lake overtopping hazards. By synthesizing key indicators including local relief, slope gradient, lake expansion rate, lake type, and Δt, this framework reveals significant spatial heterogeneity in overtopping hazard across the basin. a) Glacial lake expansion exhibits pronounced elevational asynchrony: low-elevation lakes respond rapidly to climatic warming, whereas mid- to high-elevation lakes lag by approximately 3–8 years, forming a sequential “low-to-high elevation release” pattern. b) Overtopping hazard is primarily governed by the combined effects of topographic potential energy and hydrological recharge type. Glacier-fed lakes situated in areas of high local relief and steep slopes are more likely to accumulate potential energy and enter unstable states, thus posing a higher overtopping hazard. c) A zoned response strategy for glacial lake hazard-informed management—comprising monitoring, prevention and control, and early warning—is proposed, offering a scientific basis for mitigating glacial lake disaster hazards on the Tibetan Plateau. • Glacial lakes exhibit elevation-dependent asynchronous acceleration of expansion. • An integrated hazard framework combining topography and climate-response dynamics. • Zonal-tiered strategy maps basin-wide overtopping hazard levels.