With the ongoing intensification of climate warming and human activities, the permafrost on the Qinghai–Tibet Plateau has exhibited a degradation trend characterized by rising ground temperatures and thickening active layers over the years. Particularly in ice-rich permafrost regions, thermal melting disasters, such as ground subsidence caused by thermal melting, pose a significant threat to infrastructure in permafrost areas. Based on monitoring data from the source region of the Datong River, this article developed a calculation model for active layer thickness (ALT) based on underlying surface types. Utilizing an underground ice distribution model established through geomorphic classification and lithological characteristics, in conjunction with the Nelson model, a risk evaluation of thermal melting disasters in the source region of Datong River was conducted. Based on the current warming trend, the future variation trend of ALT was predicted, and thermal stability was evaluated. The results indicated that ALT in the source region ranged from 1.0 to 3.5 m, with a close correlation between ALT and underlying surface types. The overall thermal stability of the source region is relatively satisfactory, yet it is inadequate in high-altitude areas and on bare ground. Compared to bare ground, swamp meadows and alpine meadows offer superior protective effects on the thermal stability of permafrost in the source region.

The northeastern margin of the Qinghai–Tibet Plateau is an ecologically fragile region that faces severe habitat fragmentation, which directly threatens regional biodiversity conservation and ecological security. To address this challenge, this study constructed a hierarchical “source-corridor-node” ecological network for the Gannan Tibetan Autonomous Prefecture by integrating Morphological Spatial Pattern Analysis (MSPA), the Minimum Cumulative Resistance (MCR) model, landscape connectivity assessment, and gravity modeling. The key results are as follows: (1) The Gannan Yellow River Water Source Replenishment Area contains 11 core ecological source regions, which are predominantly located in the southeastern regions of Diebu County and Zhouqu County, covering a total area of 4237.81 km²; (2) Ecological resistance analysis identifies high-resistance zones concentrated in anthropogenically active river valleys and urban belts (e.g., Hezuo urban area, Awanzang Town, and the G213 corridor). Low-resistance zones are predominantly situated in protected ecological enclaves (e.g., Zhagana Geopark and Gahai Wetland Reserve); (3) A total of 55 ecological corridors were identified, with a total length of 4355.77 km. Among these, 26 were classified as key ecological corridors, primarily distributed in Diebu and Zhouqu counties in the eastern part of Gannan Prefecture. These areas feature relatively concentrated ecological sources, and the key corridors play a critical role in connecting isolated ecological patches and maintaining regional ecological connectivity. (4) Across the entire territory of Gannan Prefecture, a total of 81 first-level ecological nodes and 53 second-level ecological nodes were delineated. As the core hub of the regional ecological network in Gannan Prefecture, Diebu County encompasses 60 First-level and 41 Second-level ecological nodes, respectively. The hierarchical “source-corridor-node” ecological network constructed in this study effectively enhances the overall landscape connectivity of the area. This progressive analytical framework—integrating source identification, corridor extraction, and node diagnosis—provides a scientific basis for biodiversity conservation, territorial ecological restoration, and sustainable development in high-altitude ecologically fragile zones.

Driven by China’s carbon peaking and carbon neutrality goals, pumped-storage hydropower projects have developed rapidly, while power stations in Northwest China face challenges posed by extreme temperature conditions. Unlike previous studies on asphalt mixtures under conventional freeze–thaw conditions, this study employs multiscale characterization methods to investigate the deterioration behavior of dense-graded hydraulic asphalt concrete under extreme temperature cycling. SBS-modified asphalt concrete specimens were vacuum-saturated and subjected to 0, 5, 10, 15, and 20 accelerated freeze–thaw cycles over a temperature range from −45 to + 60 °C. Uniaxial compression tests, relative mass change measurements, MIP, CT with three-dimensional pore reconstruction, and SEM were employed. The results show that compressive strength gradually decreased with increasing freeze–thaw cycles, while mercury-accessible pore volume, relative mass change, and interfacial defects progressively increased. After 20 cycles, compressive strength decreased by 9.29%, while the mercury-accessible volume of large capillary pores increased by 19.05%. SEM observations of the selected fields revealed more pronounced pores and cracks near the aggregate–asphalt mastic interface. These findings suggest that the aggregate–asphalt mastic interface is one of the relatively vulnerable regions under extreme cyclic exposure, although changes in the asphalt binder itself may also contribute to material deterioration. This study provides experimental evidence for understanding the deterioration behavior of hydraulic asphalt concrete under extreme temperature conditions.