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Permafrost distribution in the Qinghai-Tibet Engineering Corridor (QTEC) is of growing interest due to the increase in infrastructure development in this remote area. Empirical models of mountain permafrost distribution have been established based on field sampled data, as a tool for regional-scale assessments of its distribution. This kind of model approach has never been applied for a large portion of this engineering corridor. In the present study, this methodology is applied to map permafrost distribution throughout the QTEC. After spatial modelling of the mean annual air temperature distribution from MODIS-LST and DEM, using high-resolution satellite image to interpret land surface type, a permafrost probability index was obtained. The evaluation results indicate that the model has an acceptable performance. Conditions highly favorable to permafrost presence (≥70%) are predicted for 60.3% of the study area, declaring a discontinuous permafrost distribution in the QTEC. This map is useful for the infrastructure development along the QTEC. In the future, local ground-truth observations will be required to confirm permafrost presence in favorable areas and to monitor permafrost evolution under the influence of climate change.

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The Qinghai-Tibet Plateau (QTP) is referred to as the world's "third pole" and is characterized by a warming rate that has been more than twice the global average during the past five decades (Kuang & Jiao, 2016). Significant changes in air temperature have resulted in wide permafrost degradation thereon (Yang et al., 2019). Retrogressive thaw slump refers to the failure of a hill slope associated with exposed ground ice thawing and the subsequent slumping of thawed soil. It is a common landform associated with permafrost thawing or degradation in permafrost regions (Lewkowicz & Way, 2019;Zwieback et al., 2020). Initiated by the exposure of ice-rich sediments, RTSs generally result in the creation of a near vertical headwall and a scar area that contains mud slurry that was formed by the materials that have been ablated from the headwall (Burn & Lewkowicz, 1990;Kokelj et al., 2015). RTSs can be triggered by any process that exposes ice-rich permafrost such as lateral stream or coastal erosion (French, 2017;Ramage et al., 2018), surface water flow inducing the melting of a channelized ice wedge (Jorgenson & Osterkamp, 2005), and the occurrence of active-layer detachment slides (ALDSs;Jorgenson & Osterkamp, 2005;Luo et al., 2019). After an RTS is formed, the exposed permafrost in the headwall will thaw in the warm season, which leads to a continuous retreat over time.Widespread RTS activity has been observed in most Arctic and subarctic permafrost regions in recent years in association with persistent climate warming and permafrost degradation (